Merge remote-tracking branch 'origin/5.0.x'

modules/openapi-generator/src/main/resources/rust-server/client-imports.mustache

@@ -8,6 +8,7 @@ use hyper::{Body, Uri, Response};
 use hyper_openssl::HttpsConnector;
 use serde_json;
 use std::borrow::Cow;
+use std::convert::TryInto;
 use std::io::{Read, Error, ErrorKind};
 use std::error;
 use std::fmt;

modules/openapi-generator/src/main/resources/rust-server/client-operation.mustache

@@ -332,15 +332,23 @@
         // Header parameters
 {{/-first}}
 {{^isMapContainer}}
-{{#required}}
+{{^required}}
+        match param_{{{paramName}}} {
+            Some(param_{{{paramName}}}) => {
+{{/required}}
         request.headers_mut().append(
             HeaderName::from_static("{{{nameInLowerCase}}}"),
-            header::IntoHeaderValue(param_{{{paramName}}}.clone()).into());
+            match header::IntoHeaderValue(param_{{{paramName}}}.clone()).try_into() {
-{{/required}}
+                Ok(header) => header,
+                Err(e) => {
+                    return Box::new(future::err(ApiError(format!(
+                        "Invalid header {{{paramName}}} - {}", e)))) as Box<dyn Future<Item=_, Error=_> + Send>;
+                },
+            });
 {{^required}}
-        param_{{{paramName}}}.map(|value| request.headers_mut().append(
+            },
-            HeaderName::from_static("{{{nameInLowerCase}}}"),
+            None => {}
-            header::IntoHeaderValue(value.clone()).into()));
+        }
 {{/required}}
 {{/isMapContainer}}
 {{#isMapContainer}}
@@ -359,6 +367,14 @@
                         Some(response_{{{name}}}) => response_{{{name}}}.clone(),
                         None => return Box::new(future::err(ApiError(String::from("Required response header {{{baseName}}} for response {{{code}}} was not found.")))) as Box<dyn Future<Item=_, Error=_> + Send>,
                     };
+                    let response_{{{name}}} = match TryInto::<header::IntoHeaderValue<{{{dataType}}}>>::try_into(response_{{{name}}}) {
+                        Ok(value) => value,
+                        Err(e) => {
+                            return Box::new(future::err(ApiError(format!("Invalid response header {{baseName}} for response {{code}} - {}", e)))) as Box<dyn Future<Item=_, Error=_> + Send>;
+                        },
+                    };
+                    let response_{{{name}}} = response_{{{name}}}.0;
+
 {{/headers}}
                     let body = response.into_body();
                     Box::new(
@@ -402,7 +418,7 @@
                             {
                                 body: body,
   {{/-first}}
-                                {{{name}}}: (*Into::<header::IntoHeaderValue<{{{dataType}}}>>::into(response_{{{name}}})).clone(),
+                                {{{name}}}: response_{{name}},
   {{#-last}}
                             }
   {{/-last}}
@@ -416,7 +432,7 @@
   {{#-first}}
                             {
   {{/-first}}
-                              {{{name}}}: (*Into::<header::IntoHeaderValue<{{{dataType}}}>>::into(response_{{{name}}})).clone(),
+                                {{{name}}}: response_{{name}},
   {{#-last}}
                             }
   {{/-last}}

modules/openapi-generator/src/main/resources/rust-server/header.mustache

@@ -1,5 +1,6 @@
 use chrono::{DateTime, Utc};
 use hyper::header::HeaderValue;
+use std::convert::TryFrom;
 use std::fmt;
 use std::ops::Deref;
 
@@ -19,19 +20,31 @@ impl<T> Deref for IntoHeaderValue<T> {
     }
 }
 
-// Derive for each From<T> in hyper::header::HeaderValue
+// Derive for each TryFrom<T> in hyper::header::HeaderValue
 
 macro_rules! ihv_generate {
     ($t:ident) => {
-        impl From<HeaderValue> for IntoHeaderValue<$t> {
+        impl TryFrom<HeaderValue> for IntoHeaderValue<$t> {
-            fn from(hdr_value: HeaderValue) -> Self {
+            type Error = String;
-                IntoHeaderValue(hdr_value.to_str().unwrap().parse::<$t>().unwrap())
+
+            fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+                match hdr_value.to_str() {
+                    Ok(hdr_value) => match hdr_value.parse::<$t>() {
+                        Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value)),
+                        Err(e) => Err(format!("Unable to parse {} as a string: {}",
+                            stringify!($t), e)),
+                    },
+                    Err(e) => Err(format!("Unable to parse header {:?} as a string - {}",
+                        hdr_value, e)),
+                }
             }
         }
 
-        impl From<IntoHeaderValue<$t>> for HeaderValue {
+        impl TryFrom<IntoHeaderValue<$t>> for HeaderValue {
-            fn from(hdr_value: IntoHeaderValue<$t>) -> Self {
+            type Error = String;
-                hdr_value.0.into()
+
+            fn try_from(hdr_value: IntoHeaderValue<$t>) -> Result<Self, Self::Error> {
+                Ok(hdr_value.0.into())
             }
         }
     };
@@ -48,52 +61,120 @@ ihv_generate!(i32);
 
 // Custom derivations
 
-impl From<HeaderValue> for IntoHeaderValue<Vec<String>> {
+// Vec<String>
-    fn from(hdr_value: HeaderValue) -> Self {
+
-        IntoHeaderValue(
+impl TryFrom<HeaderValue> for IntoHeaderValue<Vec<String>> {
-            hdr_value
+    type Error = String;
-                .to_str()
+
-                .unwrap()
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => Ok(IntoHeaderValue(
+                hdr_value
                 .split(',')
                 .filter_map(|x| match x.trim() {
                     "" => None,
                     y => Some(y.to_string()),
                 })
-                .collect(),
+                .collect())),
-        )
+            Err(e) => Err(format!("Unable to parse header: {:?} as a string - {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<Vec<String>>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<Vec<String>>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<Vec<String>>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(&hdr_value.0.join(", ")).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<Vec<String>>) -> Result<Self, Self::Error> {
+       match HeaderValue::from_str(&hdr_value.0.join(", ")) {
+           Ok(hdr_value) => Ok(hdr_value),
+           Err(e) => Err(format!("Unable to convert {:?} into a header - {}",
+               hdr_value, e))
+       }
     }
 }
 
-impl From<HeaderValue> for IntoHeaderValue<String> {
+// String
-    fn from(hdr_value: HeaderValue) -> Self {
+
-        IntoHeaderValue(hdr_value.to_str().unwrap().to_string())
+impl TryFrom<HeaderValue> for IntoHeaderValue<String> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value.to_string())),
+            Err(e) => Err(format!("Unable to convert header {:?} to {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<String>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<String>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<String>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(&hdr_value.0).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<String>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(&hdr_value.0) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert {:?} from a header {}",
+                hdr_value, e))
+        }
     }
 }
 
-impl From<HeaderValue> for IntoHeaderValue<DateTime<Utc>> {
+// bool
-    fn from(hdr_value: HeaderValue) -> Self {
+impl TryFrom<HeaderValue> for IntoHeaderValue<bool> {
-        IntoHeaderValue(
+    type Error = String;
-            DateTime::parse_from_rfc3339(hdr_value.to_str().unwrap())
+
-                .unwrap()
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
-                .with_timezone(&Utc),
+        match hdr_value.to_str() {
-        )
+            Ok(hdr_value) => match hdr_value.parse() {
+                Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value)),
+                Err(e) => Err(format!("Unable to parse bool from {} - {}",
+                    hdr_value, e)),
+            },
+            Err(e) => Err(format!("Unable to convert {:?} from a header {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<DateTime<Utc>>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<bool>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<DateTime<Utc>>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(hdr_value.0.to_rfc3339().as_str()).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<bool>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(&hdr_value.0.to_string()) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert: {:?} into a header: {}",
+                hdr_value, e))
+        }
+    }
+}
+
+// DateTime
+
+impl TryFrom<HeaderValue> for IntoHeaderValue<DateTime<Utc>> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => match DateTime::parse_from_rfc3339(hdr_value) {
+                Ok(date) => Ok(IntoHeaderValue(date.with_timezone(&Utc))),
+                Err(e) => Err(format!("Unable to parse: {} as date - {}",
+                    hdr_value, e)),
+            },
+            Err(e) => Err(format!("Unable to convert header {:?} to string {}",
+                    hdr_value, e)),
+        }
+    }
+}
+
+impl TryFrom<IntoHeaderValue<DateTime<Utc>>> for HeaderValue {
+    type Error = String;
+
+    fn try_from(hdr_value: IntoHeaderValue<DateTime<Utc>>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(hdr_value.0.to_rfc3339().as_str()) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert {:?} to a header: {}",
+                hdr_value, e)),
+        }
     }
 }

modules/openapi-generator/src/main/resources/rust-server/models.mustache

@@ -124,16 +124,38 @@ impl ::std::str::FromStr for {{{classname}}} {
 // Methods for converting between header::IntoHeaderValue<{{{classname}}}> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<{{{classname}}}>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<{{{classname}}}>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<{{{classname}}}>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<{{{classname}}}>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for {{classname}} - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<{{{classname}}}> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<{{{classname}}}> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<{{{classname}}} as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <{{{classname}}} as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into {{classname}} - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 

modules/openapi-generator/src/main/resources/rust-server/server-imports.mustache

@@ -5,6 +5,8 @@ use hyper::{Request, Response, Error, StatusCode, Body, HeaderMap};
 use hyper::header::{HeaderName, HeaderValue, CONTENT_TYPE};
 use log::warn;
 use serde_json;
+#[allow(unused_imports)]
+use std::convert::{TryFrom, TryInto};
 use std::io;
 use url::form_urlencoded;
 #[allow(unused_imports)]

modules/openapi-generator/src/main/resources/rust-server/server-operation.mustache

@@ -87,20 +87,35 @@
   {{/-first}}
                 let param_{{{paramName}}} = headers.get(HeaderName::from_static("{{{nameInLowerCase}}}"));
 
-{{#required}}
                 let param_{{{paramName}}} = match param_{{{paramName}}} {
-                    Some(v) => header::IntoHeaderValue::<{{{dataType}}}>::from((*v).clone()).0,
+                    Some(v) => match header::IntoHeaderValue::<{{{dataType}}}>::try_from((*v).clone()) {
-                    None => return Box::new(future::ok(Response::builder()
+                        Ok(result) =>
-                                        .status(StatusCode::BAD_REQUEST)
+{{#required}}
-                                        .body(Body::from("Missing or invalid required header {{{baseName}}}"))
+                            result.0,
-                                        .expect("Unable to create Bad Request response for missing required header {{{baseName}}}"))),
-                };
 {{/required}}
 {{^required}}
-                let param_{{{paramName}}} = param_{{{paramName}}}.map(|p| {
+                            Some(result.0),
-                        header::IntoHeaderValue::<{{{dataType}}}>::from((*p).clone()).0
-                });
 {{/required}}
+                        Err(err) => {
+                            return Box::new(future::ok(Response::builder()
+                                        .status(StatusCode::BAD_REQUEST)
+                                        .body(Body::from(format!("Invalid header {{{baseName}}} - {}", err)))
+                                        .expect("Unable to create Bad Request response for invalid header {{{baseName}}}")));
+
+                        },
+                    },
+                    None => {
+{{#required}}
+                        return Box::new(future::ok(Response::builder()
+                                        .status(StatusCode::BAD_REQUEST)
+                                        .body(Body::from("Missing required header {{{baseName}}}"))
+                                        .expect("Unable to create Bad Request response for missing required header {{{baseName}}}")));
+{{/required}}
+{{^required}}
+                        None
+{{/required}}
+                    }
+                };
   {{#-last}}
 
   {{/-last}}
@@ -486,11 +501,23 @@
 {{/headers}}
 {{/dataType}}
                                                 => {
+{{#headers}}
+                                                    let {{{name}}} = match header::IntoHeaderValue({{{name}}}).try_into() {
+                                                        Ok(val) => val,
+                                                        Err(e) => {
+                                                            return future::ok(Response::builder()
+                                                                    .status(StatusCode::INTERNAL_SERVER_ERROR)
+                                                                    .body(Body::from(format!("An internal server error occurred handling {{name}} header - {}", e)))
+                                                                    .expect("Unable to create Internal Server Error for invalid response header"))
+                                                        }
+                                                    };
+
+{{/headers}}
                                                     *response.status_mut() = StatusCode::from_u16({{{code}}}).expect("Unable to turn {{{code}}} into a StatusCode");
 {{#headers}}
                                                     response.headers_mut().insert(
                                                         HeaderName::from_static("{{{nameInLowerCase}}}"),
-                                                        header::IntoHeaderValue({{name}}).into()
+                                                        {{name}}
                                                     );
 {{/headers}}
 {{#produces}}

modules/openapi-generator/src/test/resources/3_0/rust-server/openapi-v3.yaml

@@ -227,6 +227,9 @@ paths:
             Success-Info:
               schema:
                 type: String
+            Bool-Header:
+              schema:
+                type: bool
             Object-Header:
               schema:
                 $ref: "#/components/schemas/ObjectHeader"

samples/server/petstore/rust-server/output/multipart-v3/src/client/mod.rs

@@ -8,6 +8,7 @@ use hyper::{Body, Uri, Response};
 use hyper_openssl::HttpsConnector;
 use serde_json;
 use std::borrow::Cow;
+use std::convert::TryInto;
 use std::io::{Read, Error, ErrorKind};
 use std::error;
 use std::fmt;

samples/server/petstore/rust-server/output/multipart-v3/src/header.rs

@@ -1,5 +1,6 @@
 use chrono::{DateTime, Utc};
 use hyper::header::HeaderValue;
+use std::convert::TryFrom;
 use std::fmt;
 use std::ops::Deref;
 
@@ -19,19 +20,31 @@ impl<T> Deref for IntoHeaderValue<T> {
     }
 }
 
-// Derive for each From<T> in hyper::header::HeaderValue
+// Derive for each TryFrom<T> in hyper::header::HeaderValue
 
 macro_rules! ihv_generate {
     ($t:ident) => {
-        impl From<HeaderValue> for IntoHeaderValue<$t> {
+        impl TryFrom<HeaderValue> for IntoHeaderValue<$t> {
-            fn from(hdr_value: HeaderValue) -> Self {
+            type Error = String;
-                IntoHeaderValue(hdr_value.to_str().unwrap().parse::<$t>().unwrap())
+
+            fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+                match hdr_value.to_str() {
+                    Ok(hdr_value) => match hdr_value.parse::<$t>() {
+                        Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value)),
+                        Err(e) => Err(format!("Unable to parse {} as a string: {}",
+                            stringify!($t), e)),
+                    },
+                    Err(e) => Err(format!("Unable to parse header {:?} as a string - {}",
+                        hdr_value, e)),
+                }
             }
         }
 
-        impl From<IntoHeaderValue<$t>> for HeaderValue {
+        impl TryFrom<IntoHeaderValue<$t>> for HeaderValue {
-            fn from(hdr_value: IntoHeaderValue<$t>) -> Self {
+            type Error = String;
-                hdr_value.0.into()
+
+            fn try_from(hdr_value: IntoHeaderValue<$t>) -> Result<Self, Self::Error> {
+                Ok(hdr_value.0.into())
             }
         }
     };
@@ -48,52 +61,120 @@ ihv_generate!(i32);
 
 // Custom derivations
 
-impl From<HeaderValue> for IntoHeaderValue<Vec<String>> {
+// Vec<String>
-    fn from(hdr_value: HeaderValue) -> Self {
+
-        IntoHeaderValue(
+impl TryFrom<HeaderValue> for IntoHeaderValue<Vec<String>> {
-            hdr_value
+    type Error = String;
-                .to_str()
+
-                .unwrap()
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => Ok(IntoHeaderValue(
+                hdr_value
                 .split(',')
                 .filter_map(|x| match x.trim() {
                     "" => None,
                     y => Some(y.to_string()),
                 })
-                .collect(),
+                .collect())),
-        )
+            Err(e) => Err(format!("Unable to parse header: {:?} as a string - {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<Vec<String>>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<Vec<String>>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<Vec<String>>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(&hdr_value.0.join(", ")).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<Vec<String>>) -> Result<Self, Self::Error> {
+       match HeaderValue::from_str(&hdr_value.0.join(", ")) {
+           Ok(hdr_value) => Ok(hdr_value),
+           Err(e) => Err(format!("Unable to convert {:?} into a header - {}",
+               hdr_value, e))
+       }
     }
 }
 
-impl From<HeaderValue> for IntoHeaderValue<String> {
+// String
-    fn from(hdr_value: HeaderValue) -> Self {
+
-        IntoHeaderValue(hdr_value.to_str().unwrap().to_string())
+impl TryFrom<HeaderValue> for IntoHeaderValue<String> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value.to_string())),
+            Err(e) => Err(format!("Unable to convert header {:?} to {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<String>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<String>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<String>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(&hdr_value.0).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<String>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(&hdr_value.0) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert {:?} from a header {}",
+                hdr_value, e))
+        }
     }
 }
 
-impl From<HeaderValue> for IntoHeaderValue<DateTime<Utc>> {
+// bool
-    fn from(hdr_value: HeaderValue) -> Self {
+impl TryFrom<HeaderValue> for IntoHeaderValue<bool> {
-        IntoHeaderValue(
+    type Error = String;
-            DateTime::parse_from_rfc3339(hdr_value.to_str().unwrap())
+
-                .unwrap()
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
-                .with_timezone(&Utc),
+        match hdr_value.to_str() {
-        )
+            Ok(hdr_value) => match hdr_value.parse() {
+                Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value)),
+                Err(e) => Err(format!("Unable to parse bool from {} - {}",
+                    hdr_value, e)),
+            },
+            Err(e) => Err(format!("Unable to convert {:?} from a header {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<DateTime<Utc>>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<bool>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<DateTime<Utc>>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(hdr_value.0.to_rfc3339().as_str()).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<bool>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(&hdr_value.0.to_string()) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert: {:?} into a header: {}",
+                hdr_value, e))
+        }
+    }
+}
+
+// DateTime
+
+impl TryFrom<HeaderValue> for IntoHeaderValue<DateTime<Utc>> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => match DateTime::parse_from_rfc3339(hdr_value) {
+                Ok(date) => Ok(IntoHeaderValue(date.with_timezone(&Utc))),
+                Err(e) => Err(format!("Unable to parse: {} as date - {}",
+                    hdr_value, e)),
+            },
+            Err(e) => Err(format!("Unable to convert header {:?} to string {}",
+                    hdr_value, e)),
+        }
+    }
+}
+
+impl TryFrom<IntoHeaderValue<DateTime<Utc>>> for HeaderValue {
+    type Error = String;
+
+    fn try_from(hdr_value: IntoHeaderValue<DateTime<Utc>>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(hdr_value.0.to_rfc3339().as_str()) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert {:?} to a header: {}",
+                hdr_value, e)),
+        }
     }
 }

samples/server/petstore/rust-server/output/multipart-v3/src/models.rs

@@ -8,16 +8,38 @@ use crate::header;
 // Methods for converting between header::IntoHeaderValue<InlineObject> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<InlineObject>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<InlineObject>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<InlineObject>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<InlineObject>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for InlineObject - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<InlineObject> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<InlineObject> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<InlineObject as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <InlineObject as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into InlineObject - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -111,16 +133,38 @@ impl std::str::FromStr for InlineObject {
 // Methods for converting between header::IntoHeaderValue<MultipartRelatedRequest> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<MultipartRelatedRequest>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<MultipartRelatedRequest>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<MultipartRelatedRequest>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<MultipartRelatedRequest>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for MultipartRelatedRequest - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<MultipartRelatedRequest> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<MultipartRelatedRequest> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<MultipartRelatedRequest as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <MultipartRelatedRequest as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into MultipartRelatedRequest - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -223,16 +267,38 @@ impl std::str::FromStr for MultipartRelatedRequest {
 // Methods for converting between header::IntoHeaderValue<MultipartRequest> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<MultipartRequest>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<MultipartRequest>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<MultipartRequest>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<MultipartRequest>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for MultipartRequest - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<MultipartRequest> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<MultipartRequest> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<MultipartRequest as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <MultipartRequest as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into MultipartRequest - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -349,16 +415,38 @@ impl std::str::FromStr for MultipartRequest {
 // Methods for converting between header::IntoHeaderValue<MultipartRequestObjectField> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<MultipartRequestObjectField>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<MultipartRequestObjectField>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<MultipartRequestObjectField>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<MultipartRequestObjectField>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for MultipartRequestObjectField - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<MultipartRequestObjectField> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<MultipartRequestObjectField> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<MultipartRequestObjectField as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <MultipartRequestObjectField as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into MultipartRequestObjectField - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 

samples/server/petstore/rust-server/output/multipart-v3/src/server/mod.rs

@@ -5,6 +5,8 @@ use hyper::{Request, Response, Error, StatusCode, Body, HeaderMap};
 use hyper::header::{HeaderName, HeaderValue, CONTENT_TYPE};
 use log::warn;
 use serde_json;
+#[allow(unused_imports)]
+use std::convert::{TryFrom, TryInto};
 use std::io;
 use url::form_urlencoded;
 #[allow(unused_imports)]

samples/server/petstore/rust-server/output/no-example-v3/src/client/mod.rs

@@ -8,6 +8,7 @@ use hyper::{Body, Uri, Response};
 use hyper_openssl::HttpsConnector;
 use serde_json;
 use std::borrow::Cow;
+use std::convert::TryInto;
 use std::io::{Read, Error, ErrorKind};
 use std::error;
 use std::fmt;

samples/server/petstore/rust-server/output/no-example-v3/src/header.rs

@@ -1,5 +1,6 @@
 use chrono::{DateTime, Utc};
 use hyper::header::HeaderValue;
+use std::convert::TryFrom;
 use std::fmt;
 use std::ops::Deref;
 
@@ -19,19 +20,31 @@ impl<T> Deref for IntoHeaderValue<T> {
     }
 }
 
-// Derive for each From<T> in hyper::header::HeaderValue
+// Derive for each TryFrom<T> in hyper::header::HeaderValue
 
 macro_rules! ihv_generate {
     ($t:ident) => {
-        impl From<HeaderValue> for IntoHeaderValue<$t> {
+        impl TryFrom<HeaderValue> for IntoHeaderValue<$t> {
-            fn from(hdr_value: HeaderValue) -> Self {
+            type Error = String;
-                IntoHeaderValue(hdr_value.to_str().unwrap().parse::<$t>().unwrap())
+
+            fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+                match hdr_value.to_str() {
+                    Ok(hdr_value) => match hdr_value.parse::<$t>() {
+                        Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value)),
+                        Err(e) => Err(format!("Unable to parse {} as a string: {}",
+                            stringify!($t), e)),
+                    },
+                    Err(e) => Err(format!("Unable to parse header {:?} as a string - {}",
+                        hdr_value, e)),
+                }
             }
         }
 
-        impl From<IntoHeaderValue<$t>> for HeaderValue {
+        impl TryFrom<IntoHeaderValue<$t>> for HeaderValue {
-            fn from(hdr_value: IntoHeaderValue<$t>) -> Self {
+            type Error = String;
-                hdr_value.0.into()
+
+            fn try_from(hdr_value: IntoHeaderValue<$t>) -> Result<Self, Self::Error> {
+                Ok(hdr_value.0.into())
             }
         }
     };
@@ -48,52 +61,120 @@ ihv_generate!(i32);
 
 // Custom derivations
 
-impl From<HeaderValue> for IntoHeaderValue<Vec<String>> {
+// Vec<String>
-    fn from(hdr_value: HeaderValue) -> Self {
+
-        IntoHeaderValue(
+impl TryFrom<HeaderValue> for IntoHeaderValue<Vec<String>> {
-            hdr_value
+    type Error = String;
-                .to_str()
+
-                .unwrap()
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => Ok(IntoHeaderValue(
+                hdr_value
                 .split(',')
                 .filter_map(|x| match x.trim() {
                     "" => None,
                     y => Some(y.to_string()),
                 })
-                .collect(),
+                .collect())),
-        )
+            Err(e) => Err(format!("Unable to parse header: {:?} as a string - {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<Vec<String>>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<Vec<String>>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<Vec<String>>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(&hdr_value.0.join(", ")).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<Vec<String>>) -> Result<Self, Self::Error> {
+       match HeaderValue::from_str(&hdr_value.0.join(", ")) {
+           Ok(hdr_value) => Ok(hdr_value),
+           Err(e) => Err(format!("Unable to convert {:?} into a header - {}",
+               hdr_value, e))
+       }
     }
 }
 
-impl From<HeaderValue> for IntoHeaderValue<String> {
+// String
-    fn from(hdr_value: HeaderValue) -> Self {
+
-        IntoHeaderValue(hdr_value.to_str().unwrap().to_string())
+impl TryFrom<HeaderValue> for IntoHeaderValue<String> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value.to_string())),
+            Err(e) => Err(format!("Unable to convert header {:?} to {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<String>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<String>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<String>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(&hdr_value.0).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<String>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(&hdr_value.0) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert {:?} from a header {}",
+                hdr_value, e))
+        }
     }
 }
 
-impl From<HeaderValue> for IntoHeaderValue<DateTime<Utc>> {
+// bool
-    fn from(hdr_value: HeaderValue) -> Self {
+impl TryFrom<HeaderValue> for IntoHeaderValue<bool> {
-        IntoHeaderValue(
+    type Error = String;
-            DateTime::parse_from_rfc3339(hdr_value.to_str().unwrap())
+
-                .unwrap()
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
-                .with_timezone(&Utc),
+        match hdr_value.to_str() {
-        )
+            Ok(hdr_value) => match hdr_value.parse() {
+                Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value)),
+                Err(e) => Err(format!("Unable to parse bool from {} - {}",
+                    hdr_value, e)),
+            },
+            Err(e) => Err(format!("Unable to convert {:?} from a header {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<DateTime<Utc>>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<bool>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<DateTime<Utc>>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(hdr_value.0.to_rfc3339().as_str()).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<bool>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(&hdr_value.0.to_string()) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert: {:?} into a header: {}",
+                hdr_value, e))
+        }
+    }
+}
+
+// DateTime
+
+impl TryFrom<HeaderValue> for IntoHeaderValue<DateTime<Utc>> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => match DateTime::parse_from_rfc3339(hdr_value) {
+                Ok(date) => Ok(IntoHeaderValue(date.with_timezone(&Utc))),
+                Err(e) => Err(format!("Unable to parse: {} as date - {}",
+                    hdr_value, e)),
+            },
+            Err(e) => Err(format!("Unable to convert header {:?} to string {}",
+                    hdr_value, e)),
+        }
+    }
+}
+
+impl TryFrom<IntoHeaderValue<DateTime<Utc>>> for HeaderValue {
+    type Error = String;
+
+    fn try_from(hdr_value: IntoHeaderValue<DateTime<Utc>>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(hdr_value.0.to_rfc3339().as_str()) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert {:?} to a header: {}",
+                hdr_value, e)),
+        }
     }
 }

samples/server/petstore/rust-server/output/no-example-v3/src/models.rs

@@ -8,16 +8,38 @@ use crate::header;
 // Methods for converting between header::IntoHeaderValue<InlineObject> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<InlineObject>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<InlineObject>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<InlineObject>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<InlineObject>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for InlineObject - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<InlineObject> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<InlineObject> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<InlineObject as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <InlineObject as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into InlineObject - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 

samples/server/petstore/rust-server/output/no-example-v3/src/server/mod.rs

@@ -5,6 +5,8 @@ use hyper::{Request, Response, Error, StatusCode, Body, HeaderMap};
 use hyper::header::{HeaderName, HeaderValue, CONTENT_TYPE};
 use log::warn;
 use serde_json;
+#[allow(unused_imports)]
+use std::convert::{TryFrom, TryInto};
 use std::io;
 use url::form_urlencoded;
 #[allow(unused_imports)]

samples/server/petstore/rust-server/output/openapi-v3/api/openapi.yaml

@@ -214,6 +214,11 @@ paths:
               schema:
                 type: String
               style: simple
+            Bool-Header:
+              explode: false
+              schema:
+                type: bool
+              style: simple
             Object-Header:
               explode: false
               schema:

samples/server/petstore/rust-server/output/openapi-v3/src/client/callbacks.rs

@@ -5,6 +5,8 @@ use hyper::{Request, Response, Error, StatusCode, Body, HeaderMap};
 use hyper::header::{HeaderName, HeaderValue, CONTENT_TYPE};
 use log::warn;
 use serde_json;
+#[allow(unused_imports)]
+use std::convert::{TryFrom, TryInto};
 use std::io;
 use url::form_urlencoded;
 #[allow(unused_imports)]
@@ -151,9 +153,22 @@ where
                 // Header parameters
                 let param_information = headers.get(HeaderName::from_static("information"));
 
-                let param_information = param_information.map(|p| {
+                let param_information = match param_information {
-                        header::IntoHeaderValue::<String>::from((*p).clone()).0
+                    Some(v) => match header::IntoHeaderValue::<String>::try_from((*v).clone()) {
-                });
+                        Ok(result) =>
+                            Some(result.0),
+                        Err(err) => {
+                            return Box::new(future::ok(Response::builder()
+                                        .status(StatusCode::BAD_REQUEST)
+                                        .body(Body::from(format!("Invalid header Information - {}", err)))
+                                        .expect("Unable to create Bad Request response for invalid header Information")));
+
+                        },
+                    },
+                    None => {
+                        None
+                    }
+                };
 
                 Box::new({
                         {{

samples/server/petstore/rust-server/output/openapi-v3/src/client/mod.rs

@@ -8,6 +8,7 @@ use hyper::{Body, Uri, Response};
 use hyper_openssl::HttpsConnector;
 use serde_json;
 use std::borrow::Cow;
+use std::convert::TryInto;
 use std::io::{Read, Error, ErrorKind};
 use std::error;
 use std::fmt;
@@ -537,7 +538,13 @@ impl<C, F> Api<C> for Client<F> where
         // Header parameters
         request.headers_mut().append(
             HeaderName::from_static("x-header"),
-            header::IntoHeaderValue(param_x_header.clone()).into());
+            match header::IntoHeaderValue(param_x_header.clone()).try_into() {
+                Ok(header) => header,
+                Err(e) => {
+                    return Box::new(future::err(ApiError(format!(
+                        "Invalid header x_header - {}", e)))) as Box<dyn Future<Item=_, Error=_> + Send>;
+                },
+            });
 
         Box::new(self.client_service.request(request)
                              .map_err(|e| ApiError(format!("No response received: {}", e)))
@@ -1396,10 +1403,38 @@ impl<C, F> Api<C> for Client<F> where
                         Some(response_success_info) => response_success_info.clone(),
                         None => return Box::new(future::err(ApiError(String::from("Required response header Success-Info for response 200 was not found.")))) as Box<dyn Future<Item=_, Error=_> + Send>,
                     };
+                    let response_success_info = match TryInto::<header::IntoHeaderValue<String>>::try_into(response_success_info) {
+                        Ok(value) => value,
+                        Err(e) => {
+                            return Box::new(future::err(ApiError(format!("Invalid response header Success-Info for response 200 - {}", e)))) as Box<dyn Future<Item=_, Error=_> + Send>;
+                        },
+                    };
+                    let response_success_info = response_success_info.0;
+
+                    let response_bool_header = match response.headers().get(HeaderName::from_static("bool-header")) {
+                        Some(response_bool_header) => response_bool_header.clone(),
+                        None => return Box::new(future::err(ApiError(String::from("Required response header Bool-Header for response 200 was not found.")))) as Box<dyn Future<Item=_, Error=_> + Send>,
+                    };
+                    let response_bool_header = match TryInto::<header::IntoHeaderValue<bool>>::try_into(response_bool_header) {
+                        Ok(value) => value,
+                        Err(e) => {
+                            return Box::new(future::err(ApiError(format!("Invalid response header Bool-Header for response 200 - {}", e)))) as Box<dyn Future<Item=_, Error=_> + Send>;
+                        },
+                    };
+                    let response_bool_header = response_bool_header.0;
+
                     let response_object_header = match response.headers().get(HeaderName::from_static("object-header")) {
                         Some(response_object_header) => response_object_header.clone(),
                         None => return Box::new(future::err(ApiError(String::from("Required response header Object-Header for response 200 was not found.")))) as Box<dyn Future<Item=_, Error=_> + Send>,
                     };
+                    let response_object_header = match TryInto::<header::IntoHeaderValue<models::ObjectHeader>>::try_into(response_object_header) {
+                        Ok(value) => value,
+                        Err(e) => {
+                            return Box::new(future::err(ApiError(format!("Invalid response header Object-Header for response 200 - {}", e)))) as Box<dyn Future<Item=_, Error=_> + Send>;
+                        },
+                    };
+                    let response_object_header = response_object_header.0;
+
                     let body = response.into_body();
                     Box::new(
                         body
@@ -1417,8 +1452,9 @@ impl<C, F> Api<C> for Client<F> where
                             ResponsesWithHeadersGetResponse::Success
                             {
                                 body: body,
-                                success_info: (*Into::<header::IntoHeaderValue<String>>::into(response_success_info)).clone(),
+                                success_info: response_success_info,
-                                object_header: (*Into::<header::IntoHeaderValue<models::ObjectHeader>>::into(response_object_header)).clone(),
+                                bool_header: response_bool_header,
+                                object_header: response_object_header,
                             }
                         })
                     ) as Box<dyn Future<Item=_, Error=_> + Send>
@@ -1428,17 +1464,33 @@ impl<C, F> Api<C> for Client<F> where
                         Some(response_further_info) => response_further_info.clone(),
                         None => return Box::new(future::err(ApiError(String::from("Required response header Further-Info for response 412 was not found.")))) as Box<dyn Future<Item=_, Error=_> + Send>,
                     };
+                    let response_further_info = match TryInto::<header::IntoHeaderValue<String>>::try_into(response_further_info) {
+                        Ok(value) => value,
+                        Err(e) => {
+                            return Box::new(future::err(ApiError(format!("Invalid response header Further-Info for response 412 - {}", e)))) as Box<dyn Future<Item=_, Error=_> + Send>;
+                        },
+                    };
+                    let response_further_info = response_further_info.0;
+
                     let response_failure_info = match response.headers().get(HeaderName::from_static("failure-info")) {
                         Some(response_failure_info) => response_failure_info.clone(),
                         None => return Box::new(future::err(ApiError(String::from("Required response header Failure-Info for response 412 was not found.")))) as Box<dyn Future<Item=_, Error=_> + Send>,
                     };
+                    let response_failure_info = match TryInto::<header::IntoHeaderValue<String>>::try_into(response_failure_info) {
+                        Ok(value) => value,
+                        Err(e) => {
+                            return Box::new(future::err(ApiError(format!("Invalid response header Failure-Info for response 412 - {}", e)))) as Box<dyn Future<Item=_, Error=_> + Send>;
+                        },
+                    };
+                    let response_failure_info = response_failure_info.0;
+
                     let body = response.into_body();
                     Box::new(
                         future::ok(
                             ResponsesWithHeadersGetResponse::PreconditionFailed
                             {
-                              further_info: (*Into::<header::IntoHeaderValue<String>>::into(response_further_info)).clone(),
+                                further_info: response_further_info,
-                              failure_info: (*Into::<header::IntoHeaderValue<String>>::into(response_failure_info)).clone(),
+                                failure_info: response_failure_info,
                             }
                         )
                     ) as Box<dyn Future<Item=_, Error=_> + Send>

samples/server/petstore/rust-server/output/openapi-v3/src/header.rs

@@ -1,5 +1,6 @@
 use chrono::{DateTime, Utc};
 use hyper::header::HeaderValue;
+use std::convert::TryFrom;
 use std::fmt;
 use std::ops::Deref;
 
@@ -19,19 +20,31 @@ impl<T> Deref for IntoHeaderValue<T> {
     }
 }
 
-// Derive for each From<T> in hyper::header::HeaderValue
+// Derive for each TryFrom<T> in hyper::header::HeaderValue
 
 macro_rules! ihv_generate {
     ($t:ident) => {
-        impl From<HeaderValue> for IntoHeaderValue<$t> {
+        impl TryFrom<HeaderValue> for IntoHeaderValue<$t> {
-            fn from(hdr_value: HeaderValue) -> Self {
+            type Error = String;
-                IntoHeaderValue(hdr_value.to_str().unwrap().parse::<$t>().unwrap())
+
+            fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+                match hdr_value.to_str() {
+                    Ok(hdr_value) => match hdr_value.parse::<$t>() {
+                        Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value)),
+                        Err(e) => Err(format!("Unable to parse {} as a string: {}",
+                            stringify!($t), e)),
+                    },
+                    Err(e) => Err(format!("Unable to parse header {:?} as a string - {}",
+                        hdr_value, e)),
+                }
             }
         }
 
-        impl From<IntoHeaderValue<$t>> for HeaderValue {
+        impl TryFrom<IntoHeaderValue<$t>> for HeaderValue {
-            fn from(hdr_value: IntoHeaderValue<$t>) -> Self {
+            type Error = String;
-                hdr_value.0.into()
+
+            fn try_from(hdr_value: IntoHeaderValue<$t>) -> Result<Self, Self::Error> {
+                Ok(hdr_value.0.into())
             }
         }
     };
@@ -48,52 +61,120 @@ ihv_generate!(i32);
 
 // Custom derivations
 
-impl From<HeaderValue> for IntoHeaderValue<Vec<String>> {
+// Vec<String>
-    fn from(hdr_value: HeaderValue) -> Self {
+
-        IntoHeaderValue(
+impl TryFrom<HeaderValue> for IntoHeaderValue<Vec<String>> {
-            hdr_value
+    type Error = String;
-                .to_str()
+
-                .unwrap()
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => Ok(IntoHeaderValue(
+                hdr_value
                 .split(',')
                 .filter_map(|x| match x.trim() {
                     "" => None,
                     y => Some(y.to_string()),
                 })
-                .collect(),
+                .collect())),
-        )
+            Err(e) => Err(format!("Unable to parse header: {:?} as a string - {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<Vec<String>>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<Vec<String>>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<Vec<String>>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(&hdr_value.0.join(", ")).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<Vec<String>>) -> Result<Self, Self::Error> {
+       match HeaderValue::from_str(&hdr_value.0.join(", ")) {
+           Ok(hdr_value) => Ok(hdr_value),
+           Err(e) => Err(format!("Unable to convert {:?} into a header - {}",
+               hdr_value, e))
+       }
     }
 }
 
-impl From<HeaderValue> for IntoHeaderValue<String> {
+// String
-    fn from(hdr_value: HeaderValue) -> Self {
+
-        IntoHeaderValue(hdr_value.to_str().unwrap().to_string())
+impl TryFrom<HeaderValue> for IntoHeaderValue<String> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value.to_string())),
+            Err(e) => Err(format!("Unable to convert header {:?} to {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<String>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<String>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<String>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(&hdr_value.0).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<String>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(&hdr_value.0) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert {:?} from a header {}",
+                hdr_value, e))
+        }
     }
 }
 
-impl From<HeaderValue> for IntoHeaderValue<DateTime<Utc>> {
+// bool
-    fn from(hdr_value: HeaderValue) -> Self {
+impl TryFrom<HeaderValue> for IntoHeaderValue<bool> {
-        IntoHeaderValue(
+    type Error = String;
-            DateTime::parse_from_rfc3339(hdr_value.to_str().unwrap())
+
-                .unwrap()
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
-                .with_timezone(&Utc),
+        match hdr_value.to_str() {
-        )
+            Ok(hdr_value) => match hdr_value.parse() {
+                Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value)),
+                Err(e) => Err(format!("Unable to parse bool from {} - {}",
+                    hdr_value, e)),
+            },
+            Err(e) => Err(format!("Unable to convert {:?} from a header {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<DateTime<Utc>>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<bool>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<DateTime<Utc>>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(hdr_value.0.to_rfc3339().as_str()).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<bool>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(&hdr_value.0.to_string()) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert: {:?} into a header: {}",
+                hdr_value, e))
+        }
+    }
+}
+
+// DateTime
+
+impl TryFrom<HeaderValue> for IntoHeaderValue<DateTime<Utc>> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => match DateTime::parse_from_rfc3339(hdr_value) {
+                Ok(date) => Ok(IntoHeaderValue(date.with_timezone(&Utc))),
+                Err(e) => Err(format!("Unable to parse: {} as date - {}",
+                    hdr_value, e)),
+            },
+            Err(e) => Err(format!("Unable to convert header {:?} to string {}",
+                    hdr_value, e)),
+        }
+    }
+}
+
+impl TryFrom<IntoHeaderValue<DateTime<Utc>>> for HeaderValue {
+    type Error = String;
+
+    fn try_from(hdr_value: IntoHeaderValue<DateTime<Utc>>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(hdr_value.0.to_rfc3339().as_str()) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert {:?} to a header: {}",
+                hdr_value, e)),
+        }
     }
 }

samples/server/petstore/rust-server/output/openapi-v3/src/lib.rs

@@ -119,6 +119,7 @@ pub enum ResponsesWithHeadersGetResponse {
     {
         body: String,
         success_info: String,
+        bool_header: bool,
         object_header: models::ObjectHeader
     }
     ,

samples/server/petstore/rust-server/output/openapi-v3/src/models.rs

@@ -8,16 +8,38 @@ use crate::header;
 // Methods for converting between header::IntoHeaderValue<AnotherXmlArray> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<AnotherXmlArray>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<AnotherXmlArray>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<AnotherXmlArray>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<AnotherXmlArray>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for AnotherXmlArray - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<AnotherXmlArray> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<AnotherXmlArray> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<AnotherXmlArray as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <AnotherXmlArray as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into AnotherXmlArray - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -187,16 +209,38 @@ impl AnotherXmlInner {
 // Methods for converting between header::IntoHeaderValue<AnotherXmlObject> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<AnotherXmlObject>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<AnotherXmlObject>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<AnotherXmlObject>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<AnotherXmlObject>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for AnotherXmlObject - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<AnotherXmlObject> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<AnotherXmlObject> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<AnotherXmlObject as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <AnotherXmlObject as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into AnotherXmlObject - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -301,16 +345,38 @@ impl AnotherXmlObject {
 // Methods for converting between header::IntoHeaderValue<DuplicateXmlObject> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<DuplicateXmlObject>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<DuplicateXmlObject>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<DuplicateXmlObject>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<DuplicateXmlObject>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for DuplicateXmlObject - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<DuplicateXmlObject> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<DuplicateXmlObject> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<DuplicateXmlObject as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <DuplicateXmlObject as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into DuplicateXmlObject - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -577,16 +643,38 @@ impl Error {
 // Methods for converting between header::IntoHeaderValue<InlineResponse201> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<InlineResponse201>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<InlineResponse201>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<InlineResponse201>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<InlineResponse201>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for InlineResponse201 - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<InlineResponse201> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<InlineResponse201> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<InlineResponse201 as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <InlineResponse201 as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into InlineResponse201 - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -720,16 +808,38 @@ impl MyId {
 // Methods for converting between header::IntoHeaderValue<MyIdList> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<MyIdList>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<MyIdList>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<MyIdList>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<MyIdList>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for MyIdList - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<MyIdList> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<MyIdList> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<MyIdList as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <MyIdList as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into MyIdList - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -835,16 +945,38 @@ impl MyIdList {
 // Methods for converting between header::IntoHeaderValue<NullableTest> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<NullableTest>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<NullableTest>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<NullableTest>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<NullableTest>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for NullableTest - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<NullableTest> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<NullableTest> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<NullableTest as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <NullableTest as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into NullableTest - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -999,16 +1131,38 @@ impl NullableTest {
 // Methods for converting between header::IntoHeaderValue<ObjectHeader> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<ObjectHeader>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<ObjectHeader>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<ObjectHeader>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<ObjectHeader>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for ObjectHeader - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<ObjectHeader> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<ObjectHeader> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<ObjectHeader as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <ObjectHeader as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into ObjectHeader - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -1113,16 +1267,38 @@ impl ObjectHeader {
 // Methods for converting between header::IntoHeaderValue<ObjectParam> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<ObjectParam>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<ObjectParam>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<ObjectParam>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<ObjectParam>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for ObjectParam - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<ObjectParam> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<ObjectParam> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<ObjectParam as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <ObjectParam as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into ObjectParam - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -1227,16 +1403,38 @@ impl ObjectParam {
 // Methods for converting between header::IntoHeaderValue<ObjectUntypedProps> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<ObjectUntypedProps>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<ObjectUntypedProps>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<ObjectUntypedProps>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<ObjectUntypedProps>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for ObjectUntypedProps - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<ObjectUntypedProps> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<ObjectUntypedProps> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<ObjectUntypedProps as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <ObjectUntypedProps as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into ObjectUntypedProps - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -1354,16 +1552,38 @@ impl ObjectUntypedProps {
 // Methods for converting between header::IntoHeaderValue<ObjectWithArrayOfObjects> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<ObjectWithArrayOfObjects>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<ObjectWithArrayOfObjects>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<ObjectWithArrayOfObjects>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<ObjectWithArrayOfObjects>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for ObjectWithArrayOfObjects - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<ObjectWithArrayOfObjects> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<ObjectWithArrayOfObjects> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<ObjectWithArrayOfObjects as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <ObjectWithArrayOfObjects as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into ObjectWithArrayOfObjects - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -1778,16 +1998,38 @@ impl UuidObject {
 // Methods for converting between header::IntoHeaderValue<XmlArray> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<XmlArray>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<XmlArray>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<XmlArray>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<XmlArray>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for XmlArray - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<XmlArray> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<XmlArray> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<XmlArray as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <XmlArray as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into XmlArray - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -1957,16 +2199,38 @@ impl XmlInner {
 // Methods for converting between header::IntoHeaderValue<XmlObject> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<XmlObject>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<XmlObject>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<XmlObject>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<XmlObject>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for XmlObject - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<XmlObject> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<XmlObject> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<XmlObject as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <XmlObject as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into XmlObject - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 

samples/server/petstore/rust-server/output/openapi-v3/src/server/callbacks.rs

@@ -8,6 +8,7 @@ use hyper::{Body, Uri, Response};
 use hyper_openssl::HttpsConnector;
 use serde_json;
 use std::borrow::Cow;
+use std::convert::TryInto;
 use std::io::{Read, Error, ErrorKind};
 use std::error;
 use std::fmt;
@@ -211,9 +212,20 @@ impl<C, F> CallbackApi<C> for Client<F> where
         });
 
         // Header parameters
-        param_information.map(|value| request.headers_mut().append(
+        match param_information {
+            Some(param_information) => {
+        request.headers_mut().append(
             HeaderName::from_static("information"),
-            header::IntoHeaderValue(value.clone()).into()));
+            match header::IntoHeaderValue(param_information.clone()).try_into() {
+                Ok(header) => header,
+                Err(e) => {
+                    return Box::new(future::err(ApiError(format!(
+                        "Invalid header information - {}", e)))) as Box<dyn Future<Item=_, Error=_> + Send>;
+                },
+            });
+            },
+            None => {}
+        }
 
         Box::new(self.client_service.request(request)
                              .map_err(|e| ApiError(format!("No response received: {}", e)))

samples/server/petstore/rust-server/output/openapi-v3/src/server/mod.rs

@@ -5,6 +5,8 @@ use hyper::{Request, Response, Error, StatusCode, Body, HeaderMap};
 use hyper::header::{HeaderName, HeaderValue, CONTENT_TYPE};
 use log::warn;
 use serde_json;
+#[allow(unused_imports)]
+use std::convert::{TryFrom, TryInto};
 use std::io;
 use url::form_urlencoded;
 #[allow(unused_imports)]
@@ -365,11 +367,23 @@ where
                 let param_x_header = headers.get(HeaderName::from_static("x-header"));
 
                 let param_x_header = match param_x_header {
-                    Some(v) => header::IntoHeaderValue::<String>::from((*v).clone()).0,
+                    Some(v) => match header::IntoHeaderValue::<String>::try_from((*v).clone()) {
-                    None => return Box::new(future::ok(Response::builder()
+                        Ok(result) =>
+                            result.0,
+                        Err(err) => {
+                            return Box::new(future::ok(Response::builder()
                                         .status(StatusCode::BAD_REQUEST)
-                                        .body(Body::from("Missing or invalid required header X-Header"))
+                                        .body(Body::from(format!("Invalid header X-Header - {}", err)))
-                                        .expect("Unable to create Bad Request response for missing required header X-Header"))),
+                                        .expect("Unable to create Bad Request response for invalid header X-Header")));
+
+                        },
+                    },
+                    None => {
+                        return Box::new(future::ok(Response::builder()
+                                        .status(StatusCode::BAD_REQUEST)
+                                        .body(Body::from("Missing required header X-Header"))
+                                        .expect("Unable to create Bad Request response for missing required header X-Header")));
+                    }
                 };
 
                 Box::new({
@@ -920,17 +934,52 @@ where
                                                     {
                                                         body,
                                                         success_info,
+                                                        bool_header,
                                                         object_header
                                                     }
                                                 => {
+                                                    let success_info = match header::IntoHeaderValue(success_info).try_into() {
+                                                        Ok(val) => val,
+                                                        Err(e) => {
+                                                            return future::ok(Response::builder()
+                                                                    .status(StatusCode::INTERNAL_SERVER_ERROR)
+                                                                    .body(Body::from(format!("An internal server error occurred handling success_info header - {}", e)))
+                                                                    .expect("Unable to create Internal Server Error for invalid response header"))
+                                                        }
+                                                    };
+
+                                                    let bool_header = match header::IntoHeaderValue(bool_header).try_into() {
+                                                        Ok(val) => val,
+                                                        Err(e) => {
+                                                            return future::ok(Response::builder()
+                                                                    .status(StatusCode::INTERNAL_SERVER_ERROR)
+                                                                    .body(Body::from(format!("An internal server error occurred handling bool_header header - {}", e)))
+                                                                    .expect("Unable to create Internal Server Error for invalid response header"))
+                                                        }
+                                                    };
+
+                                                    let object_header = match header::IntoHeaderValue(object_header).try_into() {
+                                                        Ok(val) => val,
+                                                        Err(e) => {
+                                                            return future::ok(Response::builder()
+                                                                    .status(StatusCode::INTERNAL_SERVER_ERROR)
+                                                                    .body(Body::from(format!("An internal server error occurred handling object_header header - {}", e)))
+                                                                    .expect("Unable to create Internal Server Error for invalid response header"))
+                                                        }
+                                                    };
+
                                                     *response.status_mut() = StatusCode::from_u16(200).expect("Unable to turn 200 into a StatusCode");
                                                     response.headers_mut().insert(
                                                         HeaderName::from_static("success-info"),
-                                                        header::IntoHeaderValue(success_info).into()
+                                                        success_info
+                                                    );
+                                                    response.headers_mut().insert(
+                                                        HeaderName::from_static("bool-header"),
+                                                        bool_header
                                                     );
                                                     response.headers_mut().insert(
                                                         HeaderName::from_static("object-header"),
-                                                        header::IntoHeaderValue(object_header).into()
+                                                        object_header
                                                     );
                                                     response.headers_mut().insert(
                                                         CONTENT_TYPE,
@@ -945,14 +994,34 @@ where
                                                         failure_info
                                                     }
                                                 => {
+                                                    let further_info = match header::IntoHeaderValue(further_info).try_into() {
+                                                        Ok(val) => val,
+                                                        Err(e) => {
+                                                            return future::ok(Response::builder()
+                                                                    .status(StatusCode::INTERNAL_SERVER_ERROR)
+                                                                    .body(Body::from(format!("An internal server error occurred handling further_info header - {}", e)))
+                                                                    .expect("Unable to create Internal Server Error for invalid response header"))
+                                                        }
+                                                    };
+
+                                                    let failure_info = match header::IntoHeaderValue(failure_info).try_into() {
+                                                        Ok(val) => val,
+                                                        Err(e) => {
+                                                            return future::ok(Response::builder()
+                                                                    .status(StatusCode::INTERNAL_SERVER_ERROR)
+                                                                    .body(Body::from(format!("An internal server error occurred handling failure_info header - {}", e)))
+                                                                    .expect("Unable to create Internal Server Error for invalid response header"))
+                                                        }
+                                                    };
+
                                                     *response.status_mut() = StatusCode::from_u16(412).expect("Unable to turn 412 into a StatusCode");
                                                     response.headers_mut().insert(
                                                         HeaderName::from_static("further-info"),
-                                                        header::IntoHeaderValue(further_info).into()
+                                                        further_info
                                                     );
                                                     response.headers_mut().insert(
                                                         HeaderName::from_static("failure-info"),
-                                                        header::IntoHeaderValue(failure_info).into()
+                                                        failure_info
                                                     );
                                                 },
                                             },

samples/server/petstore/rust-server/output/ops-v3/src/client/mod.rs

@@ -8,6 +8,7 @@ use hyper::{Body, Uri, Response};
 use hyper_openssl::HttpsConnector;
 use serde_json;
 use std::borrow::Cow;
+use std::convert::TryInto;
 use std::io::{Read, Error, ErrorKind};
 use std::error;
 use std::fmt;

samples/server/petstore/rust-server/output/ops-v3/src/header.rs

@@ -1,5 +1,6 @@
 use chrono::{DateTime, Utc};
 use hyper::header::HeaderValue;
+use std::convert::TryFrom;
 use std::fmt;
 use std::ops::Deref;
 
@@ -19,19 +20,31 @@ impl<T> Deref for IntoHeaderValue<T> {
     }
 }
 
-// Derive for each From<T> in hyper::header::HeaderValue
+// Derive for each TryFrom<T> in hyper::header::HeaderValue
 
 macro_rules! ihv_generate {
     ($t:ident) => {
-        impl From<HeaderValue> for IntoHeaderValue<$t> {
+        impl TryFrom<HeaderValue> for IntoHeaderValue<$t> {
-            fn from(hdr_value: HeaderValue) -> Self {
+            type Error = String;
-                IntoHeaderValue(hdr_value.to_str().unwrap().parse::<$t>().unwrap())
+
+            fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+                match hdr_value.to_str() {
+                    Ok(hdr_value) => match hdr_value.parse::<$t>() {
+                        Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value)),
+                        Err(e) => Err(format!("Unable to parse {} as a string: {}",
+                            stringify!($t), e)),
+                    },
+                    Err(e) => Err(format!("Unable to parse header {:?} as a string - {}",
+                        hdr_value, e)),
+                }
             }
         }
 
-        impl From<IntoHeaderValue<$t>> for HeaderValue {
+        impl TryFrom<IntoHeaderValue<$t>> for HeaderValue {
-            fn from(hdr_value: IntoHeaderValue<$t>) -> Self {
+            type Error = String;
-                hdr_value.0.into()
+
+            fn try_from(hdr_value: IntoHeaderValue<$t>) -> Result<Self, Self::Error> {
+                Ok(hdr_value.0.into())
             }
         }
     };
@@ -48,52 +61,120 @@ ihv_generate!(i32);
 
 // Custom derivations
 
-impl From<HeaderValue> for IntoHeaderValue<Vec<String>> {
+// Vec<String>
-    fn from(hdr_value: HeaderValue) -> Self {
+
-        IntoHeaderValue(
+impl TryFrom<HeaderValue> for IntoHeaderValue<Vec<String>> {
-            hdr_value
+    type Error = String;
-                .to_str()
+
-                .unwrap()
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => Ok(IntoHeaderValue(
+                hdr_value
                 .split(',')
                 .filter_map(|x| match x.trim() {
                     "" => None,
                     y => Some(y.to_string()),
                 })
-                .collect(),
+                .collect())),
-        )
+            Err(e) => Err(format!("Unable to parse header: {:?} as a string - {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<Vec<String>>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<Vec<String>>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<Vec<String>>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(&hdr_value.0.join(", ")).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<Vec<String>>) -> Result<Self, Self::Error> {
+       match HeaderValue::from_str(&hdr_value.0.join(", ")) {
+           Ok(hdr_value) => Ok(hdr_value),
+           Err(e) => Err(format!("Unable to convert {:?} into a header - {}",
+               hdr_value, e))
+       }
     }
 }
 
-impl From<HeaderValue> for IntoHeaderValue<String> {
+// String
-    fn from(hdr_value: HeaderValue) -> Self {
+
-        IntoHeaderValue(hdr_value.to_str().unwrap().to_string())
+impl TryFrom<HeaderValue> for IntoHeaderValue<String> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value.to_string())),
+            Err(e) => Err(format!("Unable to convert header {:?} to {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<String>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<String>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<String>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(&hdr_value.0).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<String>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(&hdr_value.0) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert {:?} from a header {}",
+                hdr_value, e))
+        }
     }
 }
 
-impl From<HeaderValue> for IntoHeaderValue<DateTime<Utc>> {
+// bool
-    fn from(hdr_value: HeaderValue) -> Self {
+impl TryFrom<HeaderValue> for IntoHeaderValue<bool> {
-        IntoHeaderValue(
+    type Error = String;
-            DateTime::parse_from_rfc3339(hdr_value.to_str().unwrap())
+
-                .unwrap()
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
-                .with_timezone(&Utc),
+        match hdr_value.to_str() {
-        )
+            Ok(hdr_value) => match hdr_value.parse() {
+                Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value)),
+                Err(e) => Err(format!("Unable to parse bool from {} - {}",
+                    hdr_value, e)),
+            },
+            Err(e) => Err(format!("Unable to convert {:?} from a header {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<DateTime<Utc>>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<bool>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<DateTime<Utc>>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(hdr_value.0.to_rfc3339().as_str()).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<bool>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(&hdr_value.0.to_string()) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert: {:?} into a header: {}",
+                hdr_value, e))
+        }
+    }
+}
+
+// DateTime
+
+impl TryFrom<HeaderValue> for IntoHeaderValue<DateTime<Utc>> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => match DateTime::parse_from_rfc3339(hdr_value) {
+                Ok(date) => Ok(IntoHeaderValue(date.with_timezone(&Utc))),
+                Err(e) => Err(format!("Unable to parse: {} as date - {}",
+                    hdr_value, e)),
+            },
+            Err(e) => Err(format!("Unable to convert header {:?} to string {}",
+                    hdr_value, e)),
+        }
+    }
+}
+
+impl TryFrom<IntoHeaderValue<DateTime<Utc>>> for HeaderValue {
+    type Error = String;
+
+    fn try_from(hdr_value: IntoHeaderValue<DateTime<Utc>>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(hdr_value.0.to_rfc3339().as_str()) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert {:?} to a header: {}",
+                hdr_value, e)),
+        }
     }
 }

samples/server/petstore/rust-server/output/ops-v3/src/server/mod.rs

@@ -5,6 +5,8 @@ use hyper::{Request, Response, Error, StatusCode, Body, HeaderMap};
 use hyper::header::{HeaderName, HeaderValue, CONTENT_TYPE};
 use log::warn;
 use serde_json;
+#[allow(unused_imports)]
+use std::convert::{TryFrom, TryInto};
 use std::io;
 use url::form_urlencoded;
 #[allow(unused_imports)]

samples/server/petstore/rust-server/output/petstore-with-fake-endpoints-models-for-testing/src/client/mod.rs

@@ -8,6 +8,7 @@ use hyper::{Body, Uri, Response};
 use hyper_openssl::HttpsConnector;
 use serde_json;
 use std::borrow::Cow;
+use std::convert::TryInto;
 use std::io::{Read, Error, ErrorKind};
 use std::error;
 use std::fmt;
@@ -1358,13 +1359,35 @@ impl<C, F> Api<C> for Client<F> where
         });
 
         // Header parameters
-        param_enum_header_string_array.map(|value| request.headers_mut().append(
+        match param_enum_header_string_array {
+            Some(param_enum_header_string_array) => {
+        request.headers_mut().append(
             HeaderName::from_static("enum_header_string_array"),
-            header::IntoHeaderValue(value.clone()).into()));
+            match header::IntoHeaderValue(param_enum_header_string_array.clone()).try_into() {
+                Ok(header) => header,
+                Err(e) => {
+                    return Box::new(future::err(ApiError(format!(
+                        "Invalid header enum_header_string_array - {}", e)))) as Box<dyn Future<Item=_, Error=_> + Send>;
+                },
+            });
+            },
+            None => {}
+        }
 
-        param_enum_header_string.map(|value| request.headers_mut().append(
+        match param_enum_header_string {
+            Some(param_enum_header_string) => {
+        request.headers_mut().append(
             HeaderName::from_static("enum_header_string"),
-            header::IntoHeaderValue(value.clone()).into()));
+            match header::IntoHeaderValue(param_enum_header_string.clone()).try_into() {
+                Ok(header) => header,
+                Err(e) => {
+                    return Box::new(future::err(ApiError(format!(
+                        "Invalid header enum_header_string - {}", e)))) as Box<dyn Future<Item=_, Error=_> + Send>;
+                },
+            });
+            },
+            None => {}
+        }
 
         Box::new(self.client_service.request(request)
                              .map_err(|e| ApiError(format!("No response received: {}", e)))
@@ -1836,9 +1859,20 @@ impl<C, F> Api<C> for Client<F> where
         }
 
         // Header parameters
-        param_api_key.map(|value| request.headers_mut().append(
+        match param_api_key {
+            Some(param_api_key) => {
+        request.headers_mut().append(
             HeaderName::from_static("api_key"),
-            header::IntoHeaderValue(value.clone()).into()));
+            match header::IntoHeaderValue(param_api_key.clone()).try_into() {
+                Ok(header) => header,
+                Err(e) => {
+                    return Box::new(future::err(ApiError(format!(
+                        "Invalid header api_key - {}", e)))) as Box<dyn Future<Item=_, Error=_> + Send>;
+                },
+            });
+            },
+            None => {}
+        }
 
         Box::new(self.client_service.request(request)
                              .map_err(|e| ApiError(format!("No response received: {}", e)))
@@ -3431,10 +3465,26 @@ impl<C, F> Api<C> for Client<F> where
                         Some(response_x_rate_limit) => response_x_rate_limit.clone(),
                         None => return Box::new(future::err(ApiError(String::from("Required response header X-Rate-Limit for response 200 was not found.")))) as Box<dyn Future<Item=_, Error=_> + Send>,
                     };
+                    let response_x_rate_limit = match TryInto::<header::IntoHeaderValue<i32>>::try_into(response_x_rate_limit) {
+                        Ok(value) => value,
+                        Err(e) => {
+                            return Box::new(future::err(ApiError(format!("Invalid response header X-Rate-Limit for response 200 - {}", e)))) as Box<dyn Future<Item=_, Error=_> + Send>;
+                        },
+                    };
+                    let response_x_rate_limit = response_x_rate_limit.0;
+
                     let response_x_expires_after = match response.headers().get(HeaderName::from_static("x-expires-after")) {
                         Some(response_x_expires_after) => response_x_expires_after.clone(),
                         None => return Box::new(future::err(ApiError(String::from("Required response header X-Expires-After for response 200 was not found.")))) as Box<dyn Future<Item=_, Error=_> + Send>,
                     };
+                    let response_x_expires_after = match TryInto::<header::IntoHeaderValue<chrono::DateTime::<chrono::Utc>>>::try_into(response_x_expires_after) {
+                        Ok(value) => value,
+                        Err(e) => {
+                            return Box::new(future::err(ApiError(format!("Invalid response header X-Expires-After for response 200 - {}", e)))) as Box<dyn Future<Item=_, Error=_> + Send>;
+                        },
+                    };
+                    let response_x_expires_after = response_x_expires_after.0;
+
                     let body = response.into_body();
                     Box::new(
                         body
@@ -3454,8 +3504,8 @@ impl<C, F> Api<C> for Client<F> where
                             LoginUserResponse::SuccessfulOperation
                             {
                                 body: body,
-                                x_rate_limit: (*Into::<header::IntoHeaderValue<i32>>::into(response_x_rate_limit)).clone(),
+                                x_rate_limit: response_x_rate_limit,
-                                x_expires_after: (*Into::<header::IntoHeaderValue<chrono::DateTime::<chrono::Utc>>>::into(response_x_expires_after)).clone(),
+                                x_expires_after: response_x_expires_after,
                             }
                         })
                     ) as Box<dyn Future<Item=_, Error=_> + Send>

samples/server/petstore/rust-server/output/petstore-with-fake-endpoints-models-for-testing/src/header.rs

@@ -1,5 +1,6 @@
 use chrono::{DateTime, Utc};
 use hyper::header::HeaderValue;
+use std::convert::TryFrom;
 use std::fmt;
 use std::ops::Deref;
 
@@ -19,19 +20,31 @@ impl<T> Deref for IntoHeaderValue<T> {
     }
 }
 
-// Derive for each From<T> in hyper::header::HeaderValue
+// Derive for each TryFrom<T> in hyper::header::HeaderValue
 
 macro_rules! ihv_generate {
     ($t:ident) => {
-        impl From<HeaderValue> for IntoHeaderValue<$t> {
+        impl TryFrom<HeaderValue> for IntoHeaderValue<$t> {
-            fn from(hdr_value: HeaderValue) -> Self {
+            type Error = String;
-                IntoHeaderValue(hdr_value.to_str().unwrap().parse::<$t>().unwrap())
+
+            fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+                match hdr_value.to_str() {
+                    Ok(hdr_value) => match hdr_value.parse::<$t>() {
+                        Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value)),
+                        Err(e) => Err(format!("Unable to parse {} as a string: {}",
+                            stringify!($t), e)),
+                    },
+                    Err(e) => Err(format!("Unable to parse header {:?} as a string - {}",
+                        hdr_value, e)),
+                }
             }
         }
 
-        impl From<IntoHeaderValue<$t>> for HeaderValue {
+        impl TryFrom<IntoHeaderValue<$t>> for HeaderValue {
-            fn from(hdr_value: IntoHeaderValue<$t>) -> Self {
+            type Error = String;
-                hdr_value.0.into()
+
+            fn try_from(hdr_value: IntoHeaderValue<$t>) -> Result<Self, Self::Error> {
+                Ok(hdr_value.0.into())
             }
         }
     };
@@ -48,52 +61,120 @@ ihv_generate!(i32);
 
 // Custom derivations
 
-impl From<HeaderValue> for IntoHeaderValue<Vec<String>> {
+// Vec<String>
-    fn from(hdr_value: HeaderValue) -> Self {
+
-        IntoHeaderValue(
+impl TryFrom<HeaderValue> for IntoHeaderValue<Vec<String>> {
-            hdr_value
+    type Error = String;
-                .to_str()
+
-                .unwrap()
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => Ok(IntoHeaderValue(
+                hdr_value
                 .split(',')
                 .filter_map(|x| match x.trim() {
                     "" => None,
                     y => Some(y.to_string()),
                 })
-                .collect(),
+                .collect())),
-        )
+            Err(e) => Err(format!("Unable to parse header: {:?} as a string - {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<Vec<String>>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<Vec<String>>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<Vec<String>>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(&hdr_value.0.join(", ")).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<Vec<String>>) -> Result<Self, Self::Error> {
+       match HeaderValue::from_str(&hdr_value.0.join(", ")) {
+           Ok(hdr_value) => Ok(hdr_value),
+           Err(e) => Err(format!("Unable to convert {:?} into a header - {}",
+               hdr_value, e))
+       }
     }
 }
 
-impl From<HeaderValue> for IntoHeaderValue<String> {
+// String
-    fn from(hdr_value: HeaderValue) -> Self {
+
-        IntoHeaderValue(hdr_value.to_str().unwrap().to_string())
+impl TryFrom<HeaderValue> for IntoHeaderValue<String> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value.to_string())),
+            Err(e) => Err(format!("Unable to convert header {:?} to {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<String>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<String>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<String>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(&hdr_value.0).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<String>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(&hdr_value.0) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert {:?} from a header {}",
+                hdr_value, e))
+        }
     }
 }
 
-impl From<HeaderValue> for IntoHeaderValue<DateTime<Utc>> {
+// bool
-    fn from(hdr_value: HeaderValue) -> Self {
+impl TryFrom<HeaderValue> for IntoHeaderValue<bool> {
-        IntoHeaderValue(
+    type Error = String;
-            DateTime::parse_from_rfc3339(hdr_value.to_str().unwrap())
+
-                .unwrap()
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
-                .with_timezone(&Utc),
+        match hdr_value.to_str() {
-        )
+            Ok(hdr_value) => match hdr_value.parse() {
+                Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value)),
+                Err(e) => Err(format!("Unable to parse bool from {} - {}",
+                    hdr_value, e)),
+            },
+            Err(e) => Err(format!("Unable to convert {:?} from a header {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<DateTime<Utc>>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<bool>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<DateTime<Utc>>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(hdr_value.0.to_rfc3339().as_str()).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<bool>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(&hdr_value.0.to_string()) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert: {:?} into a header: {}",
+                hdr_value, e))
+        }
+    }
+}
+
+// DateTime
+
+impl TryFrom<HeaderValue> for IntoHeaderValue<DateTime<Utc>> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => match DateTime::parse_from_rfc3339(hdr_value) {
+                Ok(date) => Ok(IntoHeaderValue(date.with_timezone(&Utc))),
+                Err(e) => Err(format!("Unable to parse: {} as date - {}",
+                    hdr_value, e)),
+            },
+            Err(e) => Err(format!("Unable to convert header {:?} to string {}",
+                    hdr_value, e)),
+        }
+    }
+}
+
+impl TryFrom<IntoHeaderValue<DateTime<Utc>>> for HeaderValue {
+    type Error = String;
+
+    fn try_from(hdr_value: IntoHeaderValue<DateTime<Utc>>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(hdr_value.0.to_rfc3339().as_str()) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert {:?} to a header: {}",
+                hdr_value, e)),
+        }
     }
 }

samples/server/petstore/rust-server/output/petstore-with-fake-endpoints-models-for-testing/src/server/mod.rs

@@ -5,6 +5,8 @@ use hyper::{Request, Response, Error, StatusCode, Body, HeaderMap};
 use hyper::header::{HeaderName, HeaderValue, CONTENT_TYPE};
 use log::warn;
 use serde_json;
+#[allow(unused_imports)]
+use std::convert::{TryFrom, TryInto};
 use std::io;
 use url::form_urlencoded;
 #[allow(unused_imports)]
@@ -1026,14 +1028,40 @@ where
                 // Header parameters
                 let param_enum_header_string_array = headers.get(HeaderName::from_static("enum_header_string_array"));
 
-                let param_enum_header_string_array = param_enum_header_string_array.map(|p| {
+                let param_enum_header_string_array = match param_enum_header_string_array {
-                        header::IntoHeaderValue::<Vec<String>>::from((*p).clone()).0
+                    Some(v) => match header::IntoHeaderValue::<Vec<String>>::try_from((*v).clone()) {
-                });
+                        Ok(result) =>
+                            Some(result.0),
+                        Err(err) => {
+                            return Box::new(future::ok(Response::builder()
+                                        .status(StatusCode::BAD_REQUEST)
+                                        .body(Body::from(format!("Invalid header enum_header_string_array - {}", err)))
+                                        .expect("Unable to create Bad Request response for invalid header enum_header_string_array")));
+
+                        },
+                    },
+                    None => {
+                        None
+                    }
+                };
                 let param_enum_header_string = headers.get(HeaderName::from_static("enum_header_string"));
 
-                let param_enum_header_string = param_enum_header_string.map(|p| {
+                let param_enum_header_string = match param_enum_header_string {
-                        header::IntoHeaderValue::<String>::from((*p).clone()).0
+                    Some(v) => match header::IntoHeaderValue::<String>::try_from((*v).clone()) {
-                });
+                        Ok(result) =>
+                            Some(result.0),
+                        Err(err) => {
+                            return Box::new(future::ok(Response::builder()
+                                        .status(StatusCode::BAD_REQUEST)
+                                        .body(Body::from(format!("Invalid header enum_header_string - {}", err)))
+                                        .expect("Unable to create Bad Request response for invalid header enum_header_string")));
+
+                        },
+                    },
+                    None => {
+                        None
+                    }
+                };
 
                 // Query parameters (note that non-required or collection query parameters will ignore garbage values, rather than causing a 400 response)
                 let query_params = form_urlencoded::parse(uri.query().unwrap_or_default().as_bytes()).collect::<Vec<_>>();
@@ -1487,9 +1515,22 @@ where
                 // Header parameters
                 let param_api_key = headers.get(HeaderName::from_static("api_key"));
 
-                let param_api_key = param_api_key.map(|p| {
+                let param_api_key = match param_api_key {
-                        header::IntoHeaderValue::<String>::from((*p).clone()).0
+                    Some(v) => match header::IntoHeaderValue::<String>::try_from((*v).clone()) {
-                });
+                        Ok(result) =>
+                            Some(result.0),
+                        Err(err) => {
+                            return Box::new(future::ok(Response::builder()
+                                        .status(StatusCode::BAD_REQUEST)
+                                        .body(Body::from(format!("Invalid header api_key - {}", err)))
+                                        .expect("Unable to create Bad Request response for invalid header api_key")));
+
+                        },
+                    },
+                    None => {
+                        None
+                    }
+                };
 
                 Box::new({
                         {{
@@ -2890,14 +2931,34 @@ where
                                                         x_expires_after
                                                     }
                                                 => {
+                                                    let x_rate_limit = match header::IntoHeaderValue(x_rate_limit).try_into() {
+                                                        Ok(val) => val,
+                                                        Err(e) => {
+                                                            return future::ok(Response::builder()
+                                                                    .status(StatusCode::INTERNAL_SERVER_ERROR)
+                                                                    .body(Body::from(format!("An internal server error occurred handling x_rate_limit header - {}", e)))
+                                                                    .expect("Unable to create Internal Server Error for invalid response header"))
+                                                        }
+                                                    };
+
+                                                    let x_expires_after = match header::IntoHeaderValue(x_expires_after).try_into() {
+                                                        Ok(val) => val,
+                                                        Err(e) => {
+                                                            return future::ok(Response::builder()
+                                                                    .status(StatusCode::INTERNAL_SERVER_ERROR)
+                                                                    .body(Body::from(format!("An internal server error occurred handling x_expires_after header - {}", e)))
+                                                                    .expect("Unable to create Internal Server Error for invalid response header"))
+                                                        }
+                                                    };
+
                                                     *response.status_mut() = StatusCode::from_u16(200).expect("Unable to turn 200 into a StatusCode");
                                                     response.headers_mut().insert(
                                                         HeaderName::from_static("x-rate-limit"),
-                                                        header::IntoHeaderValue(x_rate_limit).into()
+                                                        x_rate_limit
                                                     );
                                                     response.headers_mut().insert(
                                                         HeaderName::from_static("x-expires-after"),
-                                                        header::IntoHeaderValue(x_expires_after).into()
+                                                        x_expires_after
                                                     );
                                                     response.headers_mut().insert(
                                                         CONTENT_TYPE,

samples/server/petstore/rust-server/output/rust-server-test/src/client/mod.rs

@@ -8,6 +8,7 @@ use hyper::{Body, Uri, Response};
 use hyper_openssl::HttpsConnector;
 use serde_json;
 use std::borrow::Cow;
+use std::convert::TryInto;
 use std::io::{Read, Error, ErrorKind};
 use std::error;
 use std::fmt;

samples/server/petstore/rust-server/output/rust-server-test/src/header.rs

@@ -1,5 +1,6 @@
 use chrono::{DateTime, Utc};
 use hyper::header::HeaderValue;
+use std::convert::TryFrom;
 use std::fmt;
 use std::ops::Deref;
 
@@ -19,19 +20,31 @@ impl<T> Deref for IntoHeaderValue<T> {
     }
 }
 
-// Derive for each From<T> in hyper::header::HeaderValue
+// Derive for each TryFrom<T> in hyper::header::HeaderValue
 
 macro_rules! ihv_generate {
     ($t:ident) => {
-        impl From<HeaderValue> for IntoHeaderValue<$t> {
+        impl TryFrom<HeaderValue> for IntoHeaderValue<$t> {
-            fn from(hdr_value: HeaderValue) -> Self {
+            type Error = String;
-                IntoHeaderValue(hdr_value.to_str().unwrap().parse::<$t>().unwrap())
+
+            fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+                match hdr_value.to_str() {
+                    Ok(hdr_value) => match hdr_value.parse::<$t>() {
+                        Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value)),
+                        Err(e) => Err(format!("Unable to parse {} as a string: {}",
+                            stringify!($t), e)),
+                    },
+                    Err(e) => Err(format!("Unable to parse header {:?} as a string - {}",
+                        hdr_value, e)),
+                }
             }
         }
 
-        impl From<IntoHeaderValue<$t>> for HeaderValue {
+        impl TryFrom<IntoHeaderValue<$t>> for HeaderValue {
-            fn from(hdr_value: IntoHeaderValue<$t>) -> Self {
+            type Error = String;
-                hdr_value.0.into()
+
+            fn try_from(hdr_value: IntoHeaderValue<$t>) -> Result<Self, Self::Error> {
+                Ok(hdr_value.0.into())
             }
         }
     };
@@ -48,52 +61,120 @@ ihv_generate!(i32);
 
 // Custom derivations
 
-impl From<HeaderValue> for IntoHeaderValue<Vec<String>> {
+// Vec<String>
-    fn from(hdr_value: HeaderValue) -> Self {
+
-        IntoHeaderValue(
+impl TryFrom<HeaderValue> for IntoHeaderValue<Vec<String>> {
-            hdr_value
+    type Error = String;
-                .to_str()
+
-                .unwrap()
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => Ok(IntoHeaderValue(
+                hdr_value
                 .split(',')
                 .filter_map(|x| match x.trim() {
                     "" => None,
                     y => Some(y.to_string()),
                 })
-                .collect(),
+                .collect())),
-        )
+            Err(e) => Err(format!("Unable to parse header: {:?} as a string - {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<Vec<String>>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<Vec<String>>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<Vec<String>>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(&hdr_value.0.join(", ")).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<Vec<String>>) -> Result<Self, Self::Error> {
+       match HeaderValue::from_str(&hdr_value.0.join(", ")) {
+           Ok(hdr_value) => Ok(hdr_value),
+           Err(e) => Err(format!("Unable to convert {:?} into a header - {}",
+               hdr_value, e))
+       }
     }
 }
 
-impl From<HeaderValue> for IntoHeaderValue<String> {
+// String
-    fn from(hdr_value: HeaderValue) -> Self {
+
-        IntoHeaderValue(hdr_value.to_str().unwrap().to_string())
+impl TryFrom<HeaderValue> for IntoHeaderValue<String> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value.to_string())),
+            Err(e) => Err(format!("Unable to convert header {:?} to {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<String>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<String>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<String>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(&hdr_value.0).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<String>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(&hdr_value.0) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert {:?} from a header {}",
+                hdr_value, e))
+        }
     }
 }
 
-impl From<HeaderValue> for IntoHeaderValue<DateTime<Utc>> {
+// bool
-    fn from(hdr_value: HeaderValue) -> Self {
+impl TryFrom<HeaderValue> for IntoHeaderValue<bool> {
-        IntoHeaderValue(
+    type Error = String;
-            DateTime::parse_from_rfc3339(hdr_value.to_str().unwrap())
+
-                .unwrap()
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
-                .with_timezone(&Utc),
+        match hdr_value.to_str() {
-        )
+            Ok(hdr_value) => match hdr_value.parse() {
+                Ok(hdr_value) => Ok(IntoHeaderValue(hdr_value)),
+                Err(e) => Err(format!("Unable to parse bool from {} - {}",
+                    hdr_value, e)),
+            },
+            Err(e) => Err(format!("Unable to convert {:?} from a header {}",
+                hdr_value, e)),
+        }
     }
 }
 
-impl From<IntoHeaderValue<DateTime<Utc>>> for HeaderValue {
+impl TryFrom<IntoHeaderValue<bool>> for HeaderValue {
-    fn from(hdr_value: IntoHeaderValue<DateTime<Utc>>) -> Self {
+    type Error = String;
-        HeaderValue::from_str(hdr_value.0.to_rfc3339().as_str()).unwrap()
+
+    fn try_from(hdr_value: IntoHeaderValue<bool>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(&hdr_value.0.to_string()) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert: {:?} into a header: {}",
+                hdr_value, e))
+        }
+    }
+}
+
+// DateTime
+
+impl TryFrom<HeaderValue> for IntoHeaderValue<DateTime<Utc>> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            Ok(hdr_value) => match DateTime::parse_from_rfc3339(hdr_value) {
+                Ok(date) => Ok(IntoHeaderValue(date.with_timezone(&Utc))),
+                Err(e) => Err(format!("Unable to parse: {} as date - {}",
+                    hdr_value, e)),
+            },
+            Err(e) => Err(format!("Unable to convert header {:?} to string {}",
+                    hdr_value, e)),
+        }
+    }
+}
+
+impl TryFrom<IntoHeaderValue<DateTime<Utc>>> for HeaderValue {
+    type Error = String;
+
+    fn try_from(hdr_value: IntoHeaderValue<DateTime<Utc>>) -> Result<Self, Self::Error> {
+        match HeaderValue::from_str(hdr_value.0.to_rfc3339().as_str()) {
+            Ok(hdr_value) => Ok(hdr_value),
+            Err(e) => Err(format!("Unable to convert {:?} to a header: {}",
+                hdr_value, e)),
+        }
     }
 }

samples/server/petstore/rust-server/output/rust-server-test/src/models.rs

@@ -8,16 +8,38 @@ use crate::header;
 // Methods for converting between header::IntoHeaderValue<ANullableContainer> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<ANullableContainer>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<ANullableContainer>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<ANullableContainer>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<ANullableContainer>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for ANullableContainer - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<ANullableContainer> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<ANullableContainer> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<ANullableContainer as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <ANullableContainer as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into ANullableContainer - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -169,16 +191,38 @@ impl ::std::str::FromStr for AdditionalPropertiesObject {
 // Methods for converting between header::IntoHeaderValue<AllOfObject> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<AllOfObject>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<AllOfObject>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<AllOfObject>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<AllOfObject>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for AllOfObject - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<AllOfObject> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<AllOfObject> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<AllOfObject as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <AllOfObject as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into AllOfObject - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -278,16 +322,38 @@ impl std::str::FromStr for AllOfObject {
 // Methods for converting between header::IntoHeaderValue<BaseAllOf> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<BaseAllOf>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<BaseAllOf>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<BaseAllOf>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<BaseAllOf>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for BaseAllOf - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<BaseAllOf> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<BaseAllOf> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<BaseAllOf as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <BaseAllOf as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into BaseAllOf - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -374,16 +440,38 @@ impl std::str::FromStr for BaseAllOf {
 // Methods for converting between header::IntoHeaderValue<GetYamlResponse> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<GetYamlResponse>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<GetYamlResponse>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<GetYamlResponse>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<GetYamlResponse>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for GetYamlResponse - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<GetYamlResponse> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<GetYamlResponse> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<GetYamlResponse as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <GetYamlResponse as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into GetYamlResponse - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -470,16 +558,38 @@ impl std::str::FromStr for GetYamlResponse {
 // Methods for converting between header::IntoHeaderValue<InlineObject> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<InlineObject>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<InlineObject>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<InlineObject>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<InlineObject>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for InlineObject - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<InlineObject> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<InlineObject> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<InlineObject as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <InlineObject as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into InlineObject - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -577,16 +687,38 @@ impl std::str::FromStr for InlineObject {
 // Methods for converting between header::IntoHeaderValue<ObjectOfObjects> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<ObjectOfObjects>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<ObjectOfObjects>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<ObjectOfObjects>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<ObjectOfObjects>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for ObjectOfObjects - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<ObjectOfObjects> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<ObjectOfObjects> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<ObjectOfObjects as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <ObjectOfObjects as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into ObjectOfObjects - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 
@@ -668,16 +800,38 @@ impl std::str::FromStr for ObjectOfObjects {
 // Methods for converting between header::IntoHeaderValue<ObjectOfObjectsInner> and hyper::header::HeaderValue
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<header::IntoHeaderValue<ObjectOfObjectsInner>> for hyper::header::HeaderValue {
+impl std::convert::TryFrom<header::IntoHeaderValue<ObjectOfObjectsInner>> for hyper::header::HeaderValue {
-    fn from(hdr_value: header::IntoHeaderValue<ObjectOfObjectsInner>) -> Self {
+    type Error = String;
-        hyper::header::HeaderValue::from_str(&hdr_value.to_string()).unwrap()
+
+    fn try_from(hdr_value: header::IntoHeaderValue<ObjectOfObjectsInner>) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match hyper::header::HeaderValue::from_str(&hdr_value) {
+             std::result::Result::Ok(value) => std::result::Result::Ok(value),
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Invalid header value for ObjectOfObjectsInner - value: {} is invalid {}",
+                     hdr_value, e))
+        }
     }
 }
 
 #[cfg(any(feature = "client", feature = "server"))]
-impl From<hyper::header::HeaderValue> for header::IntoHeaderValue<ObjectOfObjectsInner> {
+impl std::convert::TryFrom<hyper::header::HeaderValue> for header::IntoHeaderValue<ObjectOfObjectsInner> {
-    fn from(hdr_value: hyper::header::HeaderValue) -> Self {
+    type Error = String;
-        header::IntoHeaderValue(<ObjectOfObjectsInner as std::str::FromStr>::from_str(hdr_value.to_str().unwrap()).unwrap())
+
+    fn try_from(hdr_value: hyper::header::HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+             std::result::Result::Ok(value) => {
+                    match <ObjectOfObjectsInner as std::str::FromStr>::from_str(value) {
+                        std::result::Result::Ok(value) => std::result::Result::Ok(header::IntoHeaderValue(value)),
+                        std::result::Result::Err(err) => std::result::Result::Err(
+                            format!("Unable to convert header value '{}' into ObjectOfObjectsInner - {}",
+                                value, err))
+                    }
+             },
+             std::result::Result::Err(e) => std::result::Result::Err(
+                 format!("Unable to convert header: {:?} to string: {}",
+                     hdr_value, e))
+        }
     }
 }
 

samples/server/petstore/rust-server/output/rust-server-test/src/server/mod.rs

@@ -5,6 +5,8 @@ use hyper::{Request, Response, Error, StatusCode, Body, HeaderMap};
 use hyper::header::{HeaderName, HeaderValue, CONTENT_TYPE};
 use log::warn;
 use serde_json;
+#[allow(unused_imports)]
+use std::convert::{TryFrom, TryInto};
 use std::io;
 use url::form_urlencoded;
 #[allow(unused_imports)]