[Rust-Axum][Breaking Change] Improve the oneOf model generator (#20336)

* Improve the implementation of oneOf

* Fixed 2.0 schemas; possible freeze present

* Fix generate-samples.sh freezing

* Fix validation of primitive types

* Move oneOf handling to its own method

* Fix formatting and add comments

* Remove allOf based discriminator handling

* Implement a test for v3 oneOf

* Implement oneOf tests for rust axum

* Fix circle CI

* Fix pom path, ensure cargo is present

* Implement untagged test

* Add final and fix double underscore typo

CI/circle_parallel.sh

@@ -15,12 +15,22 @@ if [ "$NODE_INDEX" = "1" ]; then
 
   sudo apt-get -y install cpanminus
 
+  # install rust
+  curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
+  source "$HOME/.cargo/env"
+
+  echo "Testing perl"
   (cd samples/client/petstore/perl && /bin/bash ./test.bash)
+
+  echo "Testing ruby"
   (cd samples/client/petstore/ruby && mvn integration-test)
   (cd samples/client/petstore/ruby-faraday && mvn integration-test)
   (cd samples/client/petstore/ruby-httpx && mvn integration-test)
   (cd samples/client/petstore/ruby-autoload && mvn integration-test)
 
+  echo "Testing rust"
+  (cd samples/server/petstore/rust-axum && mvn integration-test)
+
 elif [ "$NODE_INDEX" = "2" ]; then
   echo "Running node $NODE_INDEX to test Go"
   # install haskell

bin/configs/manual/rust-axum-oneof-v3.yaml

@@ -0,0 +1,11 @@
+generatorName: rust-axum
+outputDir: samples/server/petstore/rust-axum/output/rust-axum-oneof
+inputSpec: modules/openapi-generator/src/test/resources/3_0/rust-axum/rust-axum-oneof.yaml
+templateDir: modules/openapi-generator/src/main/resources/rust-axum
+generateAliasAsModel: true
+additionalProperties:
+  hideGenerationTimestamp: "true"
+  packageName: rust-axum-oneof
+globalProperties:
+  skipFormModel: "false"
+enablePostProcessFile: true

bin/utils/test_file_list.yaml

@@ -49,3 +49,8 @@
   sha256: 67a9e63e13ebddac21cb236aa015edce30f5d3bd8d6adcf50044cad00d48c45e
 - filename: "samples/openapi3/client/petstore/java/jersey2-java8/src/test/java/org/openapitools/client/model/ZebraTest.java"
   sha256: 15eeb6d8a9a79d0f1930b861540d9c5780d6c49ea4fdb68269ac3e7ec481e142
+# rust axum test files
+- filename: "samples/server/petstore/rust-axum/output/rust-axum-oneof/src/tests.rs"
+  sha256: 3d4198174018cc7fd9d4bcffd950609a5bd306cf03b2fa780516f4e22a566e8c
+- filename: "samples/server/petstore/rust-axum/output/openapi-v3/src/tests.rs"
+  sha256: 356ac684b1fce91b153c63caefc1fe7472ea600ac436a19631e16bc00e986c50

modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenModel.java

@@ -1083,8 +1083,8 @@ public class CodegenModel implements IJsonSchemaValidationProperties {
         sb.append(", items='").append(items).append('\'');
         sb.append(", additionalProperties='").append(additionalProperties).append('\'');
         sb.append(", isModel='").append(isModel).append('\'');
-        sb.append(", isNull='").append(isNull);
+        sb.append(", isNull='").append(isNull).append('\'');
-        sb.append(", hasValidation='").append(hasValidation);
+        sb.append(", hasValidation='").append(hasValidation).append('\'');
         sb.append(", getAdditionalPropertiesIsAnyType=").append(getAdditionalPropertiesIsAnyType());
         sb.append(", getHasDiscriminatorWithNonEmptyMapping=").append(hasDiscriminatorWithNonEmptyMapping);
         sb.append(", getIsAnyType=").append(getIsAnyType());

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RustAxumServerCodegen.java

@@ -236,8 +236,9 @@ public class RustAxumServerCodegen extends AbstractRustCodegen implements Codege
         supportingFiles.add(new SupportingFile("header.mustache", "src", "header.rs"));
         supportingFiles.add(new SupportingFile("server-mod.mustache", "src/server", "mod.rs"));
         supportingFiles.add(new SupportingFile("apis-mod.mustache", apiPackage().replace('.', File.separatorChar), "mod.rs"));
-        supportingFiles.add(new SupportingFile("README.mustache", "", "README.md")
+        // The file gets overwritten regardless
-                .doNotOverwrite());
+        supportingFiles.add(new SupportingFile("tests.mustache", "src", "tests.rs").doNotOverwrite());
+        supportingFiles.add(new SupportingFile("README.mustache", "", "README.md").doNotOverwrite());
     }
 
     @Override
@@ -594,8 +595,105 @@ public class RustAxumServerCodegen extends AbstractRustCodegen implements Codege
         return op;
     }
 
+    private void postProcessOneOfModels(List<ModelMap> allModels) {
+        final HashMap<String, List<String>> oneOfMapDiscriminator = new HashMap<>();
+
+        for (ModelMap mo : allModels) {
+            final CodegenModel cm = mo.getModel();
+
+            final CodegenComposedSchemas cs = cm.getComposedSchemas();
+            if (cs != null) {
+                final List<CodegenProperty> csOneOf = cs.getOneOf();
+
+                if (csOneOf != null) {
+                    for (CodegenProperty model : csOneOf) {
+                        // Generate a valid name for the enum variant.
+                        // Mainly needed for primitive types.
+                        String[] modelParts = model.dataType.replace("<", "Of").replace(">", "").split("::");
+                        model.datatypeWithEnum = camelize(modelParts[modelParts.length - 1]);
+
+                        // Primitive type is not properly set, this overrides it to guarantee adequate model generation.
+                        if (!model.getDataType().matches(String.format(Locale.ROOT, ".*::%s", model.getDatatypeWithEnum()))) {
+                            model.isPrimitiveType = true;
+                        }
+                    }
+
+                    cs.setOneOf(csOneOf);
+                    cm.setComposedSchemas(cs);
+                }
+            }
+
+            if (cm.discriminator != null) {
+                for (String model : cm.oneOf) {
+                    List<String> discriminators = oneOfMapDiscriminator.getOrDefault(model, new ArrayList<>());
+                    discriminators.add(cm.discriminator.getPropertyName());
+                    oneOfMapDiscriminator.put(model, discriminators);
+                }
+            }
+        }
+
+        for (ModelMap mo : allModels) {
+            final CodegenModel cm = mo.getModel();
+
+            for (CodegenProperty var : cm.vars) {
+                var.isDiscriminator = false;
+            }
+
+            final List<String> discriminatorsForModel = oneOfMapDiscriminator.get(cm.getSchemaName());
+
+            if (discriminatorsForModel != null) {
+                for (String discriminator : discriminatorsForModel) {
+                    boolean hasDiscriminatorDefined = false;
+
+                    for (CodegenProperty var : cm.vars) {
+                        if (var.baseName.equals(discriminator)) {
+                            var.isDiscriminator = true;
+                            hasDiscriminatorDefined = true;
+                            break;
+                        }
+                    }
+
+                    // If the discriminator field is not a defined attribute in the variant structure, create it.
+                    if (!hasDiscriminatorDefined) {
+                        CodegenProperty property = new CodegenProperty();
+
+                        // Static attributes
+                        // Only strings are supported by serde for tag field types, so it's the only one we'll deal with
+                        property.openApiType = "string";
+                        property.complexType = "string";
+                        property.dataType = "String";
+                        property.datatypeWithEnum = "String";
+                        property.baseType = "string";
+                        property.required = true;
+                        property.isPrimitiveType = true;
+                        property.isString = true;
+                        property.isDiscriminator = true;
+
+                        // Attributes based on the discriminator value
+                        property.baseName = discriminator;
+                        property.name = discriminator;
+                        property.nameInCamelCase = camelize(discriminator);
+                        property.nameInPascalCase = property.nameInCamelCase.substring(0, 1).toUpperCase(Locale.ROOT) + property.nameInCamelCase.substring(1);
+                        property.nameInSnakeCase = underscore(discriminator).toUpperCase(Locale.ROOT);
+                        property.getter = String.format(Locale.ROOT, "get%s", property.nameInPascalCase);
+                        property.setter = String.format(Locale.ROOT, "set%s", property.nameInPascalCase);
+                        property.defaultValueWithParam = String.format(Locale.ROOT, " = data.%s;", property.name);
+
+                        // Attributes based on the model name
+                        property.defaultValue = String.format(Locale.ROOT, "r#\"%s\"#.to_string()", cm.getSchemaName());
+                        property.jsonSchema = String.format(Locale.ROOT, "{ \"default\":\"%s\"; \"type\":\"string\" }", cm.getSchemaName());
+
+                        cm.vars.add(property);
+                    }
+                }
+            }
+        }
+    }
+
     @Override
     public OperationsMap postProcessOperationsWithModels(final OperationsMap operationsMap, List<ModelMap> allModels) {
+        postProcessOneOfModels(allModels);
+
         final OperationMap operations = operationsMap.getOperations();
         operations.put("classnamePascalCase", camelize(operations.getClassname()));
 

modules/openapi-generator/src/main/resources/rust-axum/lib.mustache

@@ -28,3 +28,6 @@ pub mod apis;
 
 #[cfg(feature = "server")]
 pub(crate) mod header;
+
+#[cfg(test)]
+mod tests;

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

@@ -573,22 +573,71 @@ impl PartialEq for {{{classname}}} {
         self.0.get() == other.0.get()
     }
 }
+
 {{/anyOf.size}}
 {{#oneOf.size}}
-/// One of:
+{{#discriminator}}
-{{#oneOf}}
+#[derive(Debug, Clone, PartialEq, serde::Deserialize)]
-/// - {{{.}}}
+#[serde(tag = "{{{propertyBaseName}}}")]
-{{/oneOf}}
+{{/discriminator}}
-#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
+{{^discriminator}}
-pub struct {{{classname}}}(Box<serde_json::value::RawValue>);
+#[derive(Debug, Clone, PartialEq, serde::Serialize, serde::Deserialize)]
+#[serde(untagged)]
+{{/discriminator}}
+#[allow(non_camel_case_types)]
+pub enum {{{classname}}} {
+    {{#composedSchemas}}
+    {{#oneOf}}
+    {{{datatypeWithEnum}}}(Box<{{{dataType}}}>),
+    {{/oneOf}}
+    {{/composedSchemas}}
+}
 
 impl validator::Validate for {{{classname}}}
 {
     fn validate(&self) -> std::result::Result<(), validator::ValidationErrors> {
-        std::result::Result::Ok(())
+        match self {
+            {{#composedSchemas}}
+            {{#oneOf}}
+            {{#isPrimitiveType}}
+            Self::{{{datatypeWithEnum}}}(_) => std::result::Result::Ok(()),
+            {{/isPrimitiveType}}
+            {{^isPrimitiveType}}
+            Self::{{{datatypeWithEnum}}}(x) => x.validate(),
+            {{/isPrimitiveType}}
+            {{/oneOf}}
+            {{/composedSchemas}}
+        }
     }
 }
 
+{{#discriminator}}
+impl serde::Serialize for {{{classname}}} {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        where S: serde::Serializer {
+            match self {
+                {{#composedSchemas}}
+                {{#oneOf}}
+                Self::{{{datatypeWithEnum}}}(x) => x.serialize(serializer),
+                {{/oneOf}}
+                {{/composedSchemas}}
+            }
+    }
+}
+{{/discriminator}}
+
+
+
+{{#composedSchemas}}
+{{#oneOf}}
+impl From<{{{dataType}}}> for {{{classname}}} {
+    fn from(value: {{{dataType}}}) -> Self {
+        Self::{{{datatypeWithEnum}}}(Box::new(value))
+    }
+}
+{{/oneOf}}
+{{/composedSchemas}}
+
 /// Converts Query Parameters representation (style=form, explode=false) to a {{{classname}}} value
 /// as specified in https://swagger.io/docs/specification/serialization/
 /// Should be implemented in a serde deserializer
@@ -600,11 +649,6 @@ impl std::str::FromStr for {{{classname}}} {
     }
 }
 
-impl PartialEq for {{{classname}}} {
-    fn eq(&self, other: &Self) -> bool {
-        self.0.get() == other.0.get()
-    }
-}
 {{/oneOf.size}}
 {{^anyOf.size}}
 {{^oneOf.size}}
@@ -613,11 +657,15 @@ impl PartialEq for {{{classname}}} {
 pub struct {{{classname}}} {
 {{#vars}}
 {{#description}}    
-/// {{{.}}}
+    /// {{{.}}}
 {{/description}}
 {{#isEnum}}
-/// Note: inline enums are not fully supported by openapi-generator
+    /// Note: inline enums are not fully supported by openapi-generator
 {{/isEnum}}
+{{#isDiscriminator}}
+    #[serde(default = "{{{classname}}}::_name_for_{{{name}}}")]
+    #[serde(serialize_with = "{{{classname}}}::_serialize_{{{name}}}")]
+{{/isDiscriminator}}
     #[serde(rename = "{{{baseName}}}")]
 {{#hasValidation}}
     #[validate(
@@ -685,6 +733,25 @@ pub struct {{{classname}}} {
 {{/vars}}
 }
 
+
+{{#vars}}
+{{#isDiscriminator}}
+impl {{{classname}}} {
+    fn _name_for_{{{name}}}() -> String {
+        String::from("{{{classname}}}")
+    }
+
+    fn _serialize_{{{name}}}<S>(_: &String, s: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        s.serialize_str(&Self::_name_for_{{{name}}}())
+    }
+}
+{{/isDiscriminator}}
+{{/vars}}
+
+
 {{#vars}}
 {{#hasValidation}}
 {{#pattern}}

modules/openapi-generator/src/main/resources/rust-axum/tests.mustache

@@ -0,0 +1,9 @@
+#[test]
+fn std_test() {
+    assert!(true);
+}
+
+#[tokio::test]
+async fn tokio_test() {
+    assert!(true);
+}

modules/openapi-generator/src/test/resources/3_0/rust-axum/rust-axum-oneof.yaml

@@ -0,0 +1,86 @@
+openapi: "3.0.4"
+info:
+  title: "test"
+  version: "0.0.1"
+paths:
+  "/":
+    post:
+      operationId: foo
+      requestBody:
+        required: true
+        content:
+          "application/json":
+            schema:
+              "$ref": "#/components/schemas/Message"
+      responses:
+        "200":
+          description: Re-serialize and echo the request data
+          content:
+            "application/json":
+              schema:
+                "$ref": "#/components/schemas/Message"
+components:
+  schemas:
+    Message:
+      type: object
+      additionalProperties: false
+      discriminator:
+        propertyName: op
+      oneOf:
+        - "$ref": "#/components/schemas/Hello"
+        - "$ref": "#/components/schemas/Greeting"
+        - "$ref": "#/components/schemas/Goodbye"
+      title: Message
+    Hello:
+      type: object
+      additionalProperties: false
+      title: Hello
+      properties:
+        op:
+          type: string
+          enum:
+            - Hello
+          default: Hello
+        d:
+          type: object
+          properties:
+            welcome_message:
+              type: string
+          required:
+            - welcome_message
+      required:
+        - op
+        - d
+    Greeting:
+      type: object
+      additionalProperties: false
+      title: Greeting
+      properties:
+        d:
+          type: object
+          properties:
+            greet_message:
+              type: string
+          required:
+            - greet_message
+      required:
+        - d
+    Goodbye:
+      type: object
+      additionalProperties: false
+      title: Goodbye
+      properties:
+        op:
+          type: string
+          enum:
+            - Goodbye
+        d:
+          type: object
+          properties:
+            goodbye_message:
+              type: string
+          required:
+            - goodbye_message
+      required:
+        - op
+        - d

samples/server/petstore/rust-axum/output/apikey-auths/.openapi-generator/FILES

@@ -7,4 +7,5 @@ src/header.rs
 src/lib.rs
 src/models.rs
 src/server/mod.rs
+src/tests.rs
 src/types.rs

samples/server/petstore/rust-axum/output/apikey-auths/src/lib.rs

@@ -26,3 +26,6 @@ pub mod types;
 
 #[cfg(feature = "server")]
 pub(crate) mod header;
+
+#[cfg(test)]
+mod tests;

samples/server/petstore/rust-axum/output/apikey-auths/src/tests.rs

@@ -0,0 +1,9 @@
+#[test]
+fn std_test() {
+    assert!(true);
+}
+
+#[tokio::test]
+async fn tokio_test() {
+    assert!(true);
+}

samples/server/petstore/rust-axum/output/multipart-v3/.openapi-generator/FILES

@@ -7,4 +7,5 @@ src/header.rs
 src/lib.rs
 src/models.rs
 src/server/mod.rs
+src/tests.rs
 src/types.rs

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

@@ -26,3 +26,6 @@ pub mod types;
 
 #[cfg(feature = "server")]
 pub(crate) mod header;
+
+#[cfg(test)]
+mod tests;

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

@@ -0,0 +1,9 @@
+#[test]
+fn std_test() {
+    assert!(true);
+}
+
+#[tokio::test]
+async fn tokio_test() {
+    assert!(true);
+}

samples/server/petstore/rust-axum/output/openapi-v3/.openapi-generator/FILES

@@ -9,4 +9,5 @@ src/header.rs
 src/lib.rs
 src/models.rs
 src/server/mod.rs
+src/tests.rs
 src/types.rs

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

@@ -26,3 +26,6 @@ pub mod types;
 
 #[cfg(feature = "server")]
 pub(crate) mod header;
+
+#[cfg(test)]
+mod tests;

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

@@ -2764,15 +2764,31 @@ impl std::ops::DerefMut for Ok {
     }
 }
 
-/// One of:
+#[derive(Debug, Clone, PartialEq, serde::Serialize, serde::Deserialize)]
-/// - Vec<String>
+#[serde(untagged)]
-/// - i32
+#[allow(non_camel_case_types)]
-#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
+pub enum OneOfGet200Response {
-pub struct OneOfGet200Response(Box<serde_json::value::RawValue>);
+    I32(Box<i32>),
+    VecOfString(Box<Vec<String>>),
+}
 
 impl validator::Validate for OneOfGet200Response {
     fn validate(&self) -> std::result::Result<(), validator::ValidationErrors> {
-        std::result::Result::Ok(())
+        match self {
+            Self::I32(_) => std::result::Result::Ok(()),
+            Self::VecOfString(_) => std::result::Result::Ok(()),
+        }
+    }
+}
+
+impl From<i32> for OneOfGet200Response {
+    fn from(value: i32) -> Self {
+        Self::I32(Box::new(value))
+    }
+}
+impl From<Vec<String>> for OneOfGet200Response {
+    fn from(value: Vec<String>) -> Self {
+        Self::VecOfString(Box::new(value))
     }
 }
 
@@ -2787,12 +2803,6 @@ impl std::str::FromStr for OneOfGet200Response {
     }
 }
 
-impl PartialEq for OneOfGet200Response {
-    fn eq(&self, other: &Self) -> bool {
-        self.0.get() == other.0.get()
-    }
-}
-
 #[derive(Debug, Clone, PartialEq, PartialOrd, serde::Serialize, serde::Deserialize)]
 #[cfg_attr(feature = "conversion", derive(frunk::LabelledGeneric))]
 pub struct OptionalObjectHeader(i32);

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

@@ -0,0 +1,41 @@
+#[test]
+fn test_oneof_schema_untagged() {
+    use crate::models::OneOfGet200Response;
+
+    #[derive(Debug, Clone, PartialEq, serde::Serialize, serde::Deserialize)]
+    struct Test {
+        value: OneOfGet200Response,
+    }
+
+    let test0 = r#"{"value": "ignored"}"#;
+    let test1 = r#"{"value": 123}"#;
+    let test2 = r#"{"value": ["foo", "bar"]}"#;
+
+    let test3 = Test {
+        value: OneOfGet200Response::I32(123.into()),
+    };
+    let test4 = Test {
+        value: OneOfGet200Response::VecOfString(vec!["foo".to_string(), "bar".to_string()].into()),
+    };
+
+    let test5 = r#"{"value":123}"#;
+    let test6 = r#"{"value":["foo","bar"]}"#;
+
+    assert!(serde_json::from_str::<Test>(test0).is_err());
+    assert!(serde_json::from_str::<Test>(test1).is_ok());
+    assert!(serde_json::from_str::<Test>(test2).is_ok());
+
+    assert_eq!(
+        serde_json::to_string(&test3).expect("Serialization error"),
+        test5
+    );
+    assert_eq!(
+        serde_json::to_string(&test4).expect("Serialization error"),
+        test6
+    );
+}
+
+#[tokio::test]
+async fn tokio_test() {
+    assert!(true);
+}

samples/server/petstore/rust-axum/output/ops-v3/.openapi-generator/FILES

@@ -7,4 +7,5 @@ src/header.rs
 src/lib.rs
 src/models.rs
 src/server/mod.rs
+src/tests.rs
 src/types.rs

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

@@ -26,3 +26,6 @@ pub mod types;
 
 #[cfg(feature = "server")]
 pub(crate) mod header;
+
+#[cfg(test)]
+mod tests;

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

@@ -0,0 +1,9 @@
+#[test]
+fn std_test() {
+    assert!(true);
+}
+
+#[tokio::test]
+async fn tokio_test() {
+    assert!(true);
+}

samples/server/petstore/rust-axum/output/petstore-with-fake-endpoints-models-for-testing/.openapi-generator/FILES

@@ -12,4 +12,5 @@ src/header.rs
 src/lib.rs
 src/models.rs
 src/server/mod.rs
+src/tests.rs
 src/types.rs

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

@@ -26,3 +26,6 @@ pub mod types;
 
 #[cfg(feature = "server")]
 pub(crate) mod header;
+
+#[cfg(test)]
+mod tests;

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

@@ -0,0 +1,9 @@
+#[test]
+fn std_test() {
+    assert!(true);
+}
+
+#[tokio::test]
+async fn tokio_test() {
+    assert!(true);
+}

samples/server/petstore/rust-axum/output/petstore/.openapi-generator/FILES

@@ -9,4 +9,5 @@ src/header.rs
 src/lib.rs
 src/models.rs
 src/server/mod.rs
+src/tests.rs
 src/types.rs

samples/server/petstore/rust-axum/output/petstore/src/lib.rs

@@ -26,3 +26,6 @@ pub mod types;
 
 #[cfg(feature = "server")]
 pub(crate) mod header;
+
+#[cfg(test)]
+mod tests;

samples/server/petstore/rust-axum/output/petstore/src/tests.rs

@@ -0,0 +1,9 @@
+#[test]
+fn std_test() {
+    assert!(true);
+}
+
+#[tokio::test]
+async fn tokio_test() {
+    assert!(true);
+}

samples/server/petstore/rust-axum/output/ping-bearer-auth/.openapi-generator/FILES

@@ -7,4 +7,5 @@ src/header.rs
 src/lib.rs
 src/models.rs
 src/server/mod.rs
+src/tests.rs
 src/types.rs

samples/server/petstore/rust-axum/output/ping-bearer-auth/src/lib.rs

@@ -26,3 +26,6 @@ pub mod types;
 
 #[cfg(feature = "server")]
 pub(crate) mod header;
+
+#[cfg(test)]
+mod tests;

samples/server/petstore/rust-axum/output/ping-bearer-auth/src/tests.rs

@@ -0,0 +1,9 @@
+#[test]
+fn std_test() {
+    assert!(true);
+}
+
+#[tokio::test]
+async fn tokio_test() {
+    assert!(true);
+}

samples/server/petstore/rust-axum/output/rust-axum-header-uuid/.openapi-generator/FILES

@@ -7,4 +7,5 @@ src/header.rs
 src/lib.rs
 src/models.rs
 src/server/mod.rs
+src/tests.rs
 src/types.rs

samples/server/petstore/rust-axum/output/rust-axum-header-uuid/src/lib.rs

@@ -26,3 +26,6 @@ pub mod types;
 
 #[cfg(feature = "server")]
 pub(crate) mod header;
+
+#[cfg(test)]
+mod tests;

samples/server/petstore/rust-axum/output/rust-axum-header-uuid/src/tests.rs

@@ -0,0 +1,9 @@
+#[test]
+fn std_test() {
+    assert!(true);
+}
+
+#[tokio::test]
+async fn tokio_test() {
+    assert!(true);
+}

samples/server/petstore/rust-axum/output/rust-axum-oneof/.gitignore

@@ -0,0 +1,2 @@
+target
+Cargo.lock

samples/server/petstore/rust-axum/output/rust-axum-oneof/.openapi-generator-ignore

@@ -0,0 +1,23 @@
+# OpenAPI Generator Ignore
+# Generated by openapi-generator https://github.com/openapitools/openapi-generator
+
+# Use this file to prevent files from being overwritten by the generator.
+# The patterns follow closely to .gitignore or .dockerignore.
+
+# As an example, the C# client generator defines ApiClient.cs.
+# You can make changes and tell OpenAPI Generator to ignore just this file by uncommenting the following line:
+#ApiClient.cs
+
+# You can match any string of characters against a directory, file or extension with a single asterisk (*):
+#foo/*/qux
+# The above matches foo/bar/qux and foo/baz/qux, but not foo/bar/baz/qux
+
+# You can recursively match patterns against a directory, file or extension with a double asterisk (**):
+#foo/**/qux
+# This matches foo/bar/qux, foo/baz/qux, and foo/bar/baz/qux
+
+# You can also negate patterns with an exclamation (!).
+# For example, you can ignore all files in a docs folder with the file extension .md:
+#docs/*.md
+# Then explicitly reverse the ignore rule for a single file:
+#!docs/README.md

samples/server/petstore/rust-axum/output/rust-axum-oneof/.openapi-generator/FILES

@@ -0,0 +1,11 @@
+.gitignore
+Cargo.toml
+README.md
+src/apis/default.rs
+src/apis/mod.rs
+src/header.rs
+src/lib.rs
+src/models.rs
+src/server/mod.rs
+src/tests.rs
+src/types.rs

samples/server/petstore/rust-axum/output/rust-axum-oneof/.openapi-generator/VERSION

@@ -0,0 +1 @@
+7.11.0-SNAPSHOT

samples/server/petstore/rust-axum/output/rust-axum-oneof/Cargo.toml

@@ -0,0 +1,46 @@
+[package]
+name = "rust-axum-oneof"
+version = "0.0.1"
+authors = ["OpenAPI Generator team and contributors"]
+description = "No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)"
+edition = "2021"
+
+[features]
+default = ["server"]
+server = []
+conversion = [
+    "frunk",
+    "frunk_derives",
+    "frunk_core",
+    "frunk-enum-core",
+    "frunk-enum-derive",
+]
+
+[dependencies]
+async-trait = "0.1"
+axum = "0.7"
+axum-extra = { version = "0.9", features = ["cookie", "multipart"] }
+base64 = "0.22"
+bytes = "1"
+chrono = { version = "0.4", features = ["serde"] }
+frunk = { version = "0.4", optional = true }
+frunk-enum-core = { version = "0.3", optional = true }
+frunk-enum-derive = { version = "0.3", optional = true }
+frunk_core = { version = "0.4", optional = true }
+frunk_derives = { version = "0.4", optional = true }
+http = "1"
+lazy_static = "1"
+regex = "1"
+serde = { version = "1", features = ["derive"] }
+serde_json = { version = "1", features = ["raw_value"] }
+serde_urlencoded = "0.7"
+tokio = { version = "1", default-features = false, features = [
+    "signal",
+    "rt-multi-thread",
+] }
+tracing = { version = "0.1", features = ["attributes"] }
+uuid = { version = "1", features = ["serde"] }
+validator = { version = "0.19", features = ["derive"] }
+
+[dev-dependencies]
+tracing-subscriber = "0.3"

samples/server/petstore/rust-axum/output/rust-axum-oneof/README.md

@@ -0,0 +1,91 @@
+# Rust API for rust-axum-oneof
+
+No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+
+## Overview
+
+This server was generated by the [openapi-generator]
+(https://openapi-generator.tech) project. By using the
+[OpenAPI-Spec](https://github.com/OAI/OpenAPI-Specification) from a remote
+server, you can easily generate a server stub.
+
+To see how to make this your own, look here: [README]((https://openapi-generator.tech))
+
+- API version: 0.0.1
+- Generator version: 7.11.0-SNAPSHOT
+
+
+
+This autogenerated project defines an API crate `rust-axum-oneof` which contains:
+* An `Api` trait defining the API in Rust.
+* Data types representing the underlying data model.
+* Axum router which accepts HTTP requests and invokes the appropriate `Api` method for each operation.
+  * Request validations (path, query, body params) are included.
+
+## Using the generated library
+
+The generated library has a few optional features that can be activated through Cargo.
+
+* `server`
+    * This defaults to enabled and creates the basic skeleton of a server implementation based on Axum.
+    * To create the server stack you'll need to provide an implementation of the API trait to provide the server function.
+* `conversions`
+    * This defaults to disabled and creates extra derives on models to allow "transmogrification" between objects of structurally similar types.
+
+See https://doc.rust-lang.org/cargo/reference/manifest.html#the-features-section for how to use features in your `Cargo.toml`.
+
+### Example
+
+```rust
+struct ServerImpl {
+   // database: sea_orm::DbConn,
+}
+
+#[allow(unused_variables)]
+#[async_trait]
+impl rust-axum-oneof::Api for ServerImpl {
+  // API implementation goes here
+}
+
+pub async fn start_server(addr: &str) {
+    // initialize tracing
+    tracing_subscriber::fmt::init();
+
+    // Init Axum router
+    let app = rust-axum-oneof::server::new(Arc::new(ServerImpl));
+
+    // Add layers to the router
+    let app = app.layer(...);
+
+    // Run the server with graceful shutdown
+    let listener = TcpListener::bind(addr).await.unwrap();
+    axum::serve(listener, app)
+        .with_graceful_shutdown(shutdown_signal())
+        .await
+        .unwrap();
+}
+
+async fn shutdown_signal() {
+    let ctrl_c = async {
+        signal::ctrl_c()
+            .await
+            .expect("failed to install Ctrl+C handler");
+    };
+
+    #[cfg(unix)]
+    let terminate = async {
+        signal::unix::signal(signal::unix::SignalKind::terminate())
+            .expect("failed to install signal handler")
+            .recv()
+            .await;
+    };
+
+    #[cfg(not(unix))]
+    let terminate = std::future::pending::<()>();
+
+    tokio::select! {
+        _ = ctrl_c => {},
+        _ = terminate => {},
+    }
+}
+```

samples/server/petstore/rust-axum/output/rust-axum-oneof/src/apis/default.rs

@@ -0,0 +1,30 @@
+use async_trait::async_trait;
+use axum::extract::*;
+use axum_extra::extract::{CookieJar, Multipart};
+use bytes::Bytes;
+use http::Method;
+use serde::{Deserialize, Serialize};
+
+use crate::{models, types::*};
+
+#[derive(Debug, PartialEq, Serialize, Deserialize)]
+#[must_use]
+#[allow(clippy::large_enum_variant)]
+pub enum FooResponse {
+    /// Re-serialize and echo the request data
+    Status200_Re(models::Message),
+}
+
+/// Default
+#[async_trait]
+#[allow(clippy::ptr_arg)]
+pub trait Default {
+    /// Foo - POST /
+    async fn foo(
+        &self,
+        method: Method,
+        host: Host,
+        cookies: CookieJar,
+        body: models::Message,
+    ) -> Result<FooResponse, ()>;
+}

samples/server/petstore/rust-axum/output/rust-axum-oneof/src/apis/mod.rs

@@ -0,0 +1 @@
+pub mod default;

samples/server/petstore/rust-axum/output/rust-axum-oneof/src/header.rs

@@ -0,0 +1,197 @@
+use std::{convert::TryFrom, fmt, ops::Deref};
+
+use chrono::{DateTime, Utc};
+use http::HeaderValue;
+
+/// A struct to allow homogeneous conversion into a HeaderValue. We can't
+/// implement the From/Into trait on HeaderValue because we don't own
+/// either of the types.
+#[derive(Debug, Clone)]
+pub(crate) struct IntoHeaderValue<T>(pub T);
+
+// Generic implementations
+
+impl<T> Deref for IntoHeaderValue<T> {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        &self.0
+    }
+}
+
+// Derive for each TryFrom<T> in http::HeaderValue
+
+macro_rules! ihv_generate {
+    ($t:ident) => {
+        impl TryFrom<HeaderValue> for IntoHeaderValue<$t> {
+            type Error = String;
+
+            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 TryFrom<IntoHeaderValue<$t>> for HeaderValue {
+            type Error = String;
+
+            fn try_from(hdr_value: IntoHeaderValue<$t>) -> Result<Self, Self::Error> {
+                Ok(hdr_value.0.into())
+            }
+        }
+    };
+}
+
+ihv_generate!(u64);
+ihv_generate!(i64);
+ihv_generate!(i16);
+ihv_generate!(u16);
+ihv_generate!(u32);
+ihv_generate!(usize);
+ihv_generate!(isize);
+ihv_generate!(i32);
+
+// Custom derivations
+
+// Vec<String>
+
+impl TryFrom<HeaderValue> for IntoHeaderValue<Vec<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
+                    .split(',')
+                    .filter_map(|x| match x.trim() {
+                        "" => None,
+                        y => Some(y.to_string()),
+                    })
+                    .collect(),
+            )),
+            Err(e) => Err(format!(
+                "Unable to parse header: {:?} as a string - {}",
+                hdr_value, e
+            )),
+        }
+    }
+}
+
+impl TryFrom<IntoHeaderValue<Vec<String>>> for HeaderValue {
+    type Error = String;
+
+    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
+            )),
+        }
+    }
+}
+
+// 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 TryFrom<IntoHeaderValue<String>> for HeaderValue {
+    type Error = String;
+
+    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
+            )),
+        }
+    }
+}
+
+// Bool
+
+impl TryFrom<HeaderValue> for IntoHeaderValue<bool> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> Result<Self, Self::Error> {
+        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 TryFrom<IntoHeaderValue<bool>> for HeaderValue {
+    type Error = String;
+
+    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-axum/output/rust-axum-oneof/src/lib.rs

@@ -0,0 +1,31 @@
+#![allow(
+    missing_docs,
+    trivial_casts,
+    unused_variables,
+    unused_mut,
+    unused_extern_crates,
+    non_camel_case_types,
+    unused_imports,
+    unused_attributes
+)]
+#![allow(
+    clippy::derive_partial_eq_without_eq,
+    clippy::disallowed_names,
+    clippy::too_many_arguments
+)]
+
+pub const BASE_PATH: &str = "";
+pub const API_VERSION: &str = "0.0.1";
+
+#[cfg(feature = "server")]
+pub mod server;
+
+pub mod apis;
+pub mod models;
+pub mod types;
+
+#[cfg(feature = "server")]
+pub(crate) mod header;
+
+#[cfg(test)]
+mod tests;

samples/server/petstore/rust-axum/output/rust-axum-oneof/src/models.rs

@@ -0,0 +1,985 @@
+#![allow(unused_qualifications)]
+
+use http::HeaderValue;
+use validator::Validate;
+
+#[cfg(feature = "server")]
+use crate::header;
+use crate::{models, types::*};
+
+#[derive(Debug, Clone, PartialEq, serde::Serialize, serde::Deserialize, validator::Validate)]
+#[cfg_attr(feature = "conversion", derive(frunk::LabelledGeneric))]
+pub struct Goodbye {
+    /// Note: inline enums are not fully supported by openapi-generator
+    #[serde(default = "Goodbye::_name_for_op")]
+    #[serde(serialize_with = "Goodbye::_serialize_op")]
+    #[serde(rename = "op")]
+    pub op: String,
+
+    #[serde(rename = "d")]
+    pub d: models::GoodbyeD,
+}
+
+impl Goodbye {
+    fn _name_for_op() -> String {
+        String::from("Goodbye")
+    }
+
+    fn _serialize_op<S>(_: &String, s: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        s.serialize_str(&Self::_name_for_op())
+    }
+}
+
+impl Goodbye {
+    #[allow(clippy::new_without_default, clippy::too_many_arguments)]
+    pub fn new(op: String, d: models::GoodbyeD) -> Goodbye {
+        Goodbye { op, d }
+    }
+}
+
+/// Converts the Goodbye value to the Query Parameters representation (style=form, explode=false)
+/// specified in https://swagger.io/docs/specification/serialization/
+/// Should be implemented in a serde serializer
+impl std::fmt::Display for Goodbye {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let params: Vec<Option<String>> = vec![
+            Some("op".to_string()),
+            Some(self.op.to_string()),
+            // Skipping d in query parameter serialization
+        ];
+
+        write!(
+            f,
+            "{}",
+            params.into_iter().flatten().collect::<Vec<_>>().join(",")
+        )
+    }
+}
+
+/// Converts Query Parameters representation (style=form, explode=false) to a Goodbye value
+/// as specified in https://swagger.io/docs/specification/serialization/
+/// Should be implemented in a serde deserializer
+impl std::str::FromStr for Goodbye {
+    type Err = String;
+
+    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
+        /// An intermediate representation of the struct to use for parsing.
+        #[derive(Default)]
+        #[allow(dead_code)]
+        struct IntermediateRep {
+            pub op: Vec<String>,
+            pub d: Vec<models::GoodbyeD>,
+        }
+
+        let mut intermediate_rep = IntermediateRep::default();
+
+        // Parse into intermediate representation
+        let mut string_iter = s.split(',');
+        let mut key_result = string_iter.next();
+
+        while key_result.is_some() {
+            let val = match string_iter.next() {
+                Some(x) => x,
+                None => {
+                    return std::result::Result::Err(
+                        "Missing value while parsing Goodbye".to_string(),
+                    )
+                }
+            };
+
+            if let Some(key) = key_result {
+                #[allow(clippy::match_single_binding)]
+                match key {
+                    #[allow(clippy::redundant_clone)]
+                    "op" => intermediate_rep.op.push(
+                        <String as std::str::FromStr>::from_str(val).map_err(|x| x.to_string())?,
+                    ),
+                    #[allow(clippy::redundant_clone)]
+                    "d" => intermediate_rep.d.push(
+                        <models::GoodbyeD as std::str::FromStr>::from_str(val)
+                            .map_err(|x| x.to_string())?,
+                    ),
+                    _ => {
+                        return std::result::Result::Err(
+                            "Unexpected key while parsing Goodbye".to_string(),
+                        )
+                    }
+                }
+            }
+
+            // Get the next key
+            key_result = string_iter.next();
+        }
+
+        // Use the intermediate representation to return the struct
+        std::result::Result::Ok(Goodbye {
+            op: intermediate_rep
+                .op
+                .into_iter()
+                .next()
+                .ok_or_else(|| "op missing in Goodbye".to_string())?,
+            d: intermediate_rep
+                .d
+                .into_iter()
+                .next()
+                .ok_or_else(|| "d missing in Goodbye".to_string())?,
+        })
+    }
+}
+
+// Methods for converting between header::IntoHeaderValue<Goodbye> and HeaderValue
+
+#[cfg(feature = "server")]
+impl std::convert::TryFrom<header::IntoHeaderValue<Goodbye>> for HeaderValue {
+    type Error = String;
+
+    fn try_from(
+        hdr_value: header::IntoHeaderValue<Goodbye>,
+    ) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match 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 Goodbye - value: {} is invalid {}",
+                hdr_value, e
+            )),
+        }
+    }
+}
+
+#[cfg(feature = "server")]
+impl std::convert::TryFrom<HeaderValue> for header::IntoHeaderValue<Goodbye> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            std::result::Result::Ok(value) => {
+                match <Goodbye 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 Goodbye - {}",
+                        value, err
+                    )),
+                }
+            }
+            std::result::Result::Err(e) => std::result::Result::Err(format!(
+                "Unable to convert header: {:?} to string: {}",
+                hdr_value, e
+            )),
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, serde::Serialize, serde::Deserialize, validator::Validate)]
+#[cfg_attr(feature = "conversion", derive(frunk::LabelledGeneric))]
+pub struct GoodbyeD {
+    #[serde(rename = "goodbye_message")]
+    pub goodbye_message: String,
+}
+
+impl GoodbyeD {
+    #[allow(clippy::new_without_default, clippy::too_many_arguments)]
+    pub fn new(goodbye_message: String) -> GoodbyeD {
+        GoodbyeD { goodbye_message }
+    }
+}
+
+/// Converts the GoodbyeD value to the Query Parameters representation (style=form, explode=false)
+/// specified in https://swagger.io/docs/specification/serialization/
+/// Should be implemented in a serde serializer
+impl std::fmt::Display for GoodbyeD {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let params: Vec<Option<String>> = vec![
+            Some("goodbye_message".to_string()),
+            Some(self.goodbye_message.to_string()),
+        ];
+
+        write!(
+            f,
+            "{}",
+            params.into_iter().flatten().collect::<Vec<_>>().join(",")
+        )
+    }
+}
+
+/// Converts Query Parameters representation (style=form, explode=false) to a GoodbyeD value
+/// as specified in https://swagger.io/docs/specification/serialization/
+/// Should be implemented in a serde deserializer
+impl std::str::FromStr for GoodbyeD {
+    type Err = String;
+
+    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
+        /// An intermediate representation of the struct to use for parsing.
+        #[derive(Default)]
+        #[allow(dead_code)]
+        struct IntermediateRep {
+            pub goodbye_message: Vec<String>,
+        }
+
+        let mut intermediate_rep = IntermediateRep::default();
+
+        // Parse into intermediate representation
+        let mut string_iter = s.split(',');
+        let mut key_result = string_iter.next();
+
+        while key_result.is_some() {
+            let val = match string_iter.next() {
+                Some(x) => x,
+                None => {
+                    return std::result::Result::Err(
+                        "Missing value while parsing GoodbyeD".to_string(),
+                    )
+                }
+            };
+
+            if let Some(key) = key_result {
+                #[allow(clippy::match_single_binding)]
+                match key {
+                    #[allow(clippy::redundant_clone)]
+                    "goodbye_message" => intermediate_rep.goodbye_message.push(
+                        <String as std::str::FromStr>::from_str(val).map_err(|x| x.to_string())?,
+                    ),
+                    _ => {
+                        return std::result::Result::Err(
+                            "Unexpected key while parsing GoodbyeD".to_string(),
+                        )
+                    }
+                }
+            }
+
+            // Get the next key
+            key_result = string_iter.next();
+        }
+
+        // Use the intermediate representation to return the struct
+        std::result::Result::Ok(GoodbyeD {
+            goodbye_message: intermediate_rep
+                .goodbye_message
+                .into_iter()
+                .next()
+                .ok_or_else(|| "goodbye_message missing in GoodbyeD".to_string())?,
+        })
+    }
+}
+
+// Methods for converting between header::IntoHeaderValue<GoodbyeD> and HeaderValue
+
+#[cfg(feature = "server")]
+impl std::convert::TryFrom<header::IntoHeaderValue<GoodbyeD>> for HeaderValue {
+    type Error = String;
+
+    fn try_from(
+        hdr_value: header::IntoHeaderValue<GoodbyeD>,
+    ) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match 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 GoodbyeD - value: {} is invalid {}",
+                hdr_value, e
+            )),
+        }
+    }
+}
+
+#[cfg(feature = "server")]
+impl std::convert::TryFrom<HeaderValue> for header::IntoHeaderValue<GoodbyeD> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            std::result::Result::Ok(value) => {
+                match <GoodbyeD 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 GoodbyeD - {}",
+                        value, err
+                    )),
+                }
+            }
+            std::result::Result::Err(e) => std::result::Result::Err(format!(
+                "Unable to convert header: {:?} to string: {}",
+                hdr_value, e
+            )),
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, serde::Serialize, serde::Deserialize, validator::Validate)]
+#[cfg_attr(feature = "conversion", derive(frunk::LabelledGeneric))]
+pub struct Greeting {
+    #[serde(rename = "d")]
+    pub d: models::GreetingD,
+
+    #[serde(default = "Greeting::_name_for_op")]
+    #[serde(serialize_with = "Greeting::_serialize_op")]
+    #[serde(rename = "op")]
+    pub op: String,
+}
+
+impl Greeting {
+    fn _name_for_op() -> String {
+        String::from("Greeting")
+    }
+
+    fn _serialize_op<S>(_: &String, s: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        s.serialize_str(&Self::_name_for_op())
+    }
+}
+
+impl Greeting {
+    #[allow(clippy::new_without_default, clippy::too_many_arguments)]
+    pub fn new(d: models::GreetingD) -> Greeting {
+        Greeting {
+            d,
+            op: r#"Greeting"#.to_string(),
+        }
+    }
+}
+
+/// Converts the Greeting value to the Query Parameters representation (style=form, explode=false)
+/// specified in https://swagger.io/docs/specification/serialization/
+/// Should be implemented in a serde serializer
+impl std::fmt::Display for Greeting {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let params: Vec<Option<String>> = vec![
+            // Skipping d in query parameter serialization
+            Some("op".to_string()),
+            Some(self.op.to_string()),
+        ];
+
+        write!(
+            f,
+            "{}",
+            params.into_iter().flatten().collect::<Vec<_>>().join(",")
+        )
+    }
+}
+
+/// Converts Query Parameters representation (style=form, explode=false) to a Greeting value
+/// as specified in https://swagger.io/docs/specification/serialization/
+/// Should be implemented in a serde deserializer
+impl std::str::FromStr for Greeting {
+    type Err = String;
+
+    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
+        /// An intermediate representation of the struct to use for parsing.
+        #[derive(Default)]
+        #[allow(dead_code)]
+        struct IntermediateRep {
+            pub d: Vec<models::GreetingD>,
+            pub op: Vec<String>,
+        }
+
+        let mut intermediate_rep = IntermediateRep::default();
+
+        // Parse into intermediate representation
+        let mut string_iter = s.split(',');
+        let mut key_result = string_iter.next();
+
+        while key_result.is_some() {
+            let val = match string_iter.next() {
+                Some(x) => x,
+                None => {
+                    return std::result::Result::Err(
+                        "Missing value while parsing Greeting".to_string(),
+                    )
+                }
+            };
+
+            if let Some(key) = key_result {
+                #[allow(clippy::match_single_binding)]
+                match key {
+                    #[allow(clippy::redundant_clone)]
+                    "d" => intermediate_rep.d.push(
+                        <models::GreetingD as std::str::FromStr>::from_str(val)
+                            .map_err(|x| x.to_string())?,
+                    ),
+                    #[allow(clippy::redundant_clone)]
+                    "op" => intermediate_rep.op.push(
+                        <String as std::str::FromStr>::from_str(val).map_err(|x| x.to_string())?,
+                    ),
+                    _ => {
+                        return std::result::Result::Err(
+                            "Unexpected key while parsing Greeting".to_string(),
+                        )
+                    }
+                }
+            }
+
+            // Get the next key
+            key_result = string_iter.next();
+        }
+
+        // Use the intermediate representation to return the struct
+        std::result::Result::Ok(Greeting {
+            d: intermediate_rep
+                .d
+                .into_iter()
+                .next()
+                .ok_or_else(|| "d missing in Greeting".to_string())?,
+            op: intermediate_rep
+                .op
+                .into_iter()
+                .next()
+                .ok_or_else(|| "op missing in Greeting".to_string())?,
+        })
+    }
+}
+
+// Methods for converting between header::IntoHeaderValue<Greeting> and HeaderValue
+
+#[cfg(feature = "server")]
+impl std::convert::TryFrom<header::IntoHeaderValue<Greeting>> for HeaderValue {
+    type Error = String;
+
+    fn try_from(
+        hdr_value: header::IntoHeaderValue<Greeting>,
+    ) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match 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 Greeting - value: {} is invalid {}",
+                hdr_value, e
+            )),
+        }
+    }
+}
+
+#[cfg(feature = "server")]
+impl std::convert::TryFrom<HeaderValue> for header::IntoHeaderValue<Greeting> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            std::result::Result::Ok(value) => {
+                match <Greeting 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 Greeting - {}",
+                        value, err
+                    )),
+                }
+            }
+            std::result::Result::Err(e) => std::result::Result::Err(format!(
+                "Unable to convert header: {:?} to string: {}",
+                hdr_value, e
+            )),
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, serde::Serialize, serde::Deserialize, validator::Validate)]
+#[cfg_attr(feature = "conversion", derive(frunk::LabelledGeneric))]
+pub struct GreetingD {
+    #[serde(rename = "greet_message")]
+    pub greet_message: String,
+}
+
+impl GreetingD {
+    #[allow(clippy::new_without_default, clippy::too_many_arguments)]
+    pub fn new(greet_message: String) -> GreetingD {
+        GreetingD { greet_message }
+    }
+}
+
+/// Converts the GreetingD value to the Query Parameters representation (style=form, explode=false)
+/// specified in https://swagger.io/docs/specification/serialization/
+/// Should be implemented in a serde serializer
+impl std::fmt::Display for GreetingD {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let params: Vec<Option<String>> = vec![
+            Some("greet_message".to_string()),
+            Some(self.greet_message.to_string()),
+        ];
+
+        write!(
+            f,
+            "{}",
+            params.into_iter().flatten().collect::<Vec<_>>().join(",")
+        )
+    }
+}
+
+/// Converts Query Parameters representation (style=form, explode=false) to a GreetingD value
+/// as specified in https://swagger.io/docs/specification/serialization/
+/// Should be implemented in a serde deserializer
+impl std::str::FromStr for GreetingD {
+    type Err = String;
+
+    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
+        /// An intermediate representation of the struct to use for parsing.
+        #[derive(Default)]
+        #[allow(dead_code)]
+        struct IntermediateRep {
+            pub greet_message: Vec<String>,
+        }
+
+        let mut intermediate_rep = IntermediateRep::default();
+
+        // Parse into intermediate representation
+        let mut string_iter = s.split(',');
+        let mut key_result = string_iter.next();
+
+        while key_result.is_some() {
+            let val = match string_iter.next() {
+                Some(x) => x,
+                None => {
+                    return std::result::Result::Err(
+                        "Missing value while parsing GreetingD".to_string(),
+                    )
+                }
+            };
+
+            if let Some(key) = key_result {
+                #[allow(clippy::match_single_binding)]
+                match key {
+                    #[allow(clippy::redundant_clone)]
+                    "greet_message" => intermediate_rep.greet_message.push(
+                        <String as std::str::FromStr>::from_str(val).map_err(|x| x.to_string())?,
+                    ),
+                    _ => {
+                        return std::result::Result::Err(
+                            "Unexpected key while parsing GreetingD".to_string(),
+                        )
+                    }
+                }
+            }
+
+            // Get the next key
+            key_result = string_iter.next();
+        }
+
+        // Use the intermediate representation to return the struct
+        std::result::Result::Ok(GreetingD {
+            greet_message: intermediate_rep
+                .greet_message
+                .into_iter()
+                .next()
+                .ok_or_else(|| "greet_message missing in GreetingD".to_string())?,
+        })
+    }
+}
+
+// Methods for converting between header::IntoHeaderValue<GreetingD> and HeaderValue
+
+#[cfg(feature = "server")]
+impl std::convert::TryFrom<header::IntoHeaderValue<GreetingD>> for HeaderValue {
+    type Error = String;
+
+    fn try_from(
+        hdr_value: header::IntoHeaderValue<GreetingD>,
+    ) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match 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 GreetingD - value: {} is invalid {}",
+                hdr_value, e
+            )),
+        }
+    }
+}
+
+#[cfg(feature = "server")]
+impl std::convert::TryFrom<HeaderValue> for header::IntoHeaderValue<GreetingD> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            std::result::Result::Ok(value) => {
+                match <GreetingD 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 GreetingD - {}",
+                        value, err
+                    )),
+                }
+            }
+            std::result::Result::Err(e) => std::result::Result::Err(format!(
+                "Unable to convert header: {:?} to string: {}",
+                hdr_value, e
+            )),
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, serde::Serialize, serde::Deserialize, validator::Validate)]
+#[cfg_attr(feature = "conversion", derive(frunk::LabelledGeneric))]
+pub struct Hello {
+    /// Note: inline enums are not fully supported by openapi-generator
+    #[serde(default = "Hello::_name_for_op")]
+    #[serde(serialize_with = "Hello::_serialize_op")]
+    #[serde(rename = "op")]
+    pub op: String,
+
+    #[serde(rename = "d")]
+    pub d: models::HelloD,
+}
+
+impl Hello {
+    fn _name_for_op() -> String {
+        String::from("Hello")
+    }
+
+    fn _serialize_op<S>(_: &String, s: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        s.serialize_str(&Self::_name_for_op())
+    }
+}
+
+impl Hello {
+    #[allow(clippy::new_without_default, clippy::too_many_arguments)]
+    pub fn new(d: models::HelloD) -> Hello {
+        Hello {
+            op: r#"Hello"#.to_string(),
+            d,
+        }
+    }
+}
+
+/// Converts the Hello value to the Query Parameters representation (style=form, explode=false)
+/// specified in https://swagger.io/docs/specification/serialization/
+/// Should be implemented in a serde serializer
+impl std::fmt::Display for Hello {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let params: Vec<Option<String>> = vec![
+            Some("op".to_string()),
+            Some(self.op.to_string()),
+            // Skipping d in query parameter serialization
+        ];
+
+        write!(
+            f,
+            "{}",
+            params.into_iter().flatten().collect::<Vec<_>>().join(",")
+        )
+    }
+}
+
+/// Converts Query Parameters representation (style=form, explode=false) to a Hello value
+/// as specified in https://swagger.io/docs/specification/serialization/
+/// Should be implemented in a serde deserializer
+impl std::str::FromStr for Hello {
+    type Err = String;
+
+    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
+        /// An intermediate representation of the struct to use for parsing.
+        #[derive(Default)]
+        #[allow(dead_code)]
+        struct IntermediateRep {
+            pub op: Vec<String>,
+            pub d: Vec<models::HelloD>,
+        }
+
+        let mut intermediate_rep = IntermediateRep::default();
+
+        // Parse into intermediate representation
+        let mut string_iter = s.split(',');
+        let mut key_result = string_iter.next();
+
+        while key_result.is_some() {
+            let val = match string_iter.next() {
+                Some(x) => x,
+                None => {
+                    return std::result::Result::Err(
+                        "Missing value while parsing Hello".to_string(),
+                    )
+                }
+            };
+
+            if let Some(key) = key_result {
+                #[allow(clippy::match_single_binding)]
+                match key {
+                    #[allow(clippy::redundant_clone)]
+                    "op" => intermediate_rep.op.push(
+                        <String as std::str::FromStr>::from_str(val).map_err(|x| x.to_string())?,
+                    ),
+                    #[allow(clippy::redundant_clone)]
+                    "d" => intermediate_rep.d.push(
+                        <models::HelloD as std::str::FromStr>::from_str(val)
+                            .map_err(|x| x.to_string())?,
+                    ),
+                    _ => {
+                        return std::result::Result::Err(
+                            "Unexpected key while parsing Hello".to_string(),
+                        )
+                    }
+                }
+            }
+
+            // Get the next key
+            key_result = string_iter.next();
+        }
+
+        // Use the intermediate representation to return the struct
+        std::result::Result::Ok(Hello {
+            op: intermediate_rep
+                .op
+                .into_iter()
+                .next()
+                .ok_or_else(|| "op missing in Hello".to_string())?,
+            d: intermediate_rep
+                .d
+                .into_iter()
+                .next()
+                .ok_or_else(|| "d missing in Hello".to_string())?,
+        })
+    }
+}
+
+// Methods for converting between header::IntoHeaderValue<Hello> and HeaderValue
+
+#[cfg(feature = "server")]
+impl std::convert::TryFrom<header::IntoHeaderValue<Hello>> for HeaderValue {
+    type Error = String;
+
+    fn try_from(
+        hdr_value: header::IntoHeaderValue<Hello>,
+    ) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match 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 Hello - value: {} is invalid {}",
+                hdr_value, e
+            )),
+        }
+    }
+}
+
+#[cfg(feature = "server")]
+impl std::convert::TryFrom<HeaderValue> for header::IntoHeaderValue<Hello> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            std::result::Result::Ok(value) => match <Hello 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 Hello - {}",
+                    value, err
+                )),
+            },
+            std::result::Result::Err(e) => std::result::Result::Err(format!(
+                "Unable to convert header: {:?} to string: {}",
+                hdr_value, e
+            )),
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, serde::Serialize, serde::Deserialize, validator::Validate)]
+#[cfg_attr(feature = "conversion", derive(frunk::LabelledGeneric))]
+pub struct HelloD {
+    #[serde(rename = "welcome_message")]
+    pub welcome_message: String,
+}
+
+impl HelloD {
+    #[allow(clippy::new_without_default, clippy::too_many_arguments)]
+    pub fn new(welcome_message: String) -> HelloD {
+        HelloD { welcome_message }
+    }
+}
+
+/// Converts the HelloD value to the Query Parameters representation (style=form, explode=false)
+/// specified in https://swagger.io/docs/specification/serialization/
+/// Should be implemented in a serde serializer
+impl std::fmt::Display for HelloD {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let params: Vec<Option<String>> = vec![
+            Some("welcome_message".to_string()),
+            Some(self.welcome_message.to_string()),
+        ];
+
+        write!(
+            f,
+            "{}",
+            params.into_iter().flatten().collect::<Vec<_>>().join(",")
+        )
+    }
+}
+
+/// Converts Query Parameters representation (style=form, explode=false) to a HelloD value
+/// as specified in https://swagger.io/docs/specification/serialization/
+/// Should be implemented in a serde deserializer
+impl std::str::FromStr for HelloD {
+    type Err = String;
+
+    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
+        /// An intermediate representation of the struct to use for parsing.
+        #[derive(Default)]
+        #[allow(dead_code)]
+        struct IntermediateRep {
+            pub welcome_message: Vec<String>,
+        }
+
+        let mut intermediate_rep = IntermediateRep::default();
+
+        // Parse into intermediate representation
+        let mut string_iter = s.split(',');
+        let mut key_result = string_iter.next();
+
+        while key_result.is_some() {
+            let val = match string_iter.next() {
+                Some(x) => x,
+                None => {
+                    return std::result::Result::Err(
+                        "Missing value while parsing HelloD".to_string(),
+                    )
+                }
+            };
+
+            if let Some(key) = key_result {
+                #[allow(clippy::match_single_binding)]
+                match key {
+                    #[allow(clippy::redundant_clone)]
+                    "welcome_message" => intermediate_rep.welcome_message.push(
+                        <String as std::str::FromStr>::from_str(val).map_err(|x| x.to_string())?,
+                    ),
+                    _ => {
+                        return std::result::Result::Err(
+                            "Unexpected key while parsing HelloD".to_string(),
+                        )
+                    }
+                }
+            }
+
+            // Get the next key
+            key_result = string_iter.next();
+        }
+
+        // Use the intermediate representation to return the struct
+        std::result::Result::Ok(HelloD {
+            welcome_message: intermediate_rep
+                .welcome_message
+                .into_iter()
+                .next()
+                .ok_or_else(|| "welcome_message missing in HelloD".to_string())?,
+        })
+    }
+}
+
+// Methods for converting between header::IntoHeaderValue<HelloD> and HeaderValue
+
+#[cfg(feature = "server")]
+impl std::convert::TryFrom<header::IntoHeaderValue<HelloD>> for HeaderValue {
+    type Error = String;
+
+    fn try_from(
+        hdr_value: header::IntoHeaderValue<HelloD>,
+    ) -> std::result::Result<Self, Self::Error> {
+        let hdr_value = hdr_value.to_string();
+        match 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 HelloD - value: {} is invalid {}",
+                hdr_value, e
+            )),
+        }
+    }
+}
+
+#[cfg(feature = "server")]
+impl std::convert::TryFrom<HeaderValue> for header::IntoHeaderValue<HelloD> {
+    type Error = String;
+
+    fn try_from(hdr_value: HeaderValue) -> std::result::Result<Self, Self::Error> {
+        match hdr_value.to_str() {
+            std::result::Result::Ok(value) => {
+                match <HelloD 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 HelloD - {}",
+                        value, err
+                    )),
+                }
+            }
+            std::result::Result::Err(e) => std::result::Result::Err(format!(
+                "Unable to convert header: {:?} to string: {}",
+                hdr_value, e
+            )),
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, serde::Deserialize)]
+#[serde(tag = "op")]
+#[allow(non_camel_case_types)]
+pub enum Message {
+    Hello(Box<models::Hello>),
+    Greeting(Box<models::Greeting>),
+    Goodbye(Box<models::Goodbye>),
+}
+
+impl validator::Validate for Message {
+    fn validate(&self) -> std::result::Result<(), validator::ValidationErrors> {
+        match self {
+            Self::Hello(x) => x.validate(),
+            Self::Greeting(x) => x.validate(),
+            Self::Goodbye(x) => x.validate(),
+        }
+    }
+}
+
+impl serde::Serialize for Message {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        match self {
+            Self::Hello(x) => x.serialize(serializer),
+            Self::Greeting(x) => x.serialize(serializer),
+            Self::Goodbye(x) => x.serialize(serializer),
+        }
+    }
+}
+
+impl From<models::Hello> for Message {
+    fn from(value: models::Hello) -> Self {
+        Self::Hello(Box::new(value))
+    }
+}
+impl From<models::Greeting> for Message {
+    fn from(value: models::Greeting) -> Self {
+        Self::Greeting(Box::new(value))
+    }
+}
+impl From<models::Goodbye> for Message {
+    fn from(value: models::Goodbye) -> Self {
+        Self::Goodbye(Box::new(value))
+    }
+}
+
+/// Converts Query Parameters representation (style=form, explode=false) to a Message value
+/// as specified in https://swagger.io/docs/specification/serialization/
+/// Should be implemented in a serde deserializer
+impl std::str::FromStr for Message {
+    type Err = serde_json::Error;
+
+    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
+        serde_json::from_str(s)
+    }
+}

samples/server/petstore/rust-axum/output/rust-axum-oneof/src/server/mod.rs

@@ -0,0 +1,109 @@
+use std::collections::HashMap;
+
+use axum::{body::Body, extract::*, response::Response, routing::*};
+use axum_extra::extract::{CookieJar, Multipart};
+use bytes::Bytes;
+use http::{header::CONTENT_TYPE, HeaderMap, HeaderName, HeaderValue, Method, StatusCode};
+use tracing::error;
+use validator::{Validate, ValidationErrors};
+
+use crate::{header, types::*};
+
+#[allow(unused_imports)]
+use crate::{apis, models};
+
+/// Setup API Server.
+pub fn new<I, A>(api_impl: I) -> Router
+where
+    I: AsRef<A> + Clone + Send + Sync + 'static,
+    A: apis::default::Default + 'static,
+{
+    // build our application with a route
+    Router::new()
+        .route("/", post(foo::<I, A>))
+        .with_state(api_impl)
+}
+
+#[derive(validator::Validate)]
+#[allow(dead_code)]
+struct FooBodyValidator<'a> {
+    #[validate(nested)]
+    body: &'a models::Message,
+}
+
+#[tracing::instrument(skip_all)]
+fn foo_validation(
+    body: models::Message,
+) -> std::result::Result<(models::Message,), ValidationErrors> {
+    let b = FooBodyValidator { body: &body };
+    b.validate()?;
+
+    Ok((body,))
+}
+/// Foo - POST /
+#[tracing::instrument(skip_all)]
+async fn foo<I, A>(
+    method: Method,
+    host: Host,
+    cookies: CookieJar,
+    State(api_impl): State<I>,
+    Json(body): Json<models::Message>,
+) -> Result<Response, StatusCode>
+where
+    I: AsRef<A> + Send + Sync,
+    A: apis::default::Default,
+{
+    #[allow(clippy::redundant_closure)]
+    let validation = tokio::task::spawn_blocking(move || foo_validation(body))
+        .await
+        .unwrap();
+
+    let Ok((body,)) = validation else {
+        return Response::builder()
+            .status(StatusCode::BAD_REQUEST)
+            .body(Body::from(validation.unwrap_err().to_string()))
+            .map_err(|_| StatusCode::BAD_REQUEST);
+    };
+
+    let result = api_impl.as_ref().foo(method, host, cookies, body).await;
+
+    let mut response = Response::builder();
+
+    let resp = match result {
+        Ok(rsp) => match rsp {
+            apis::default::FooResponse::Status200_Re(body) => {
+                let mut response = response.status(200);
+                {
+                    let mut response_headers = response.headers_mut().unwrap();
+                    response_headers.insert(
+                        CONTENT_TYPE,
+                        HeaderValue::from_str("application/json").map_err(|e| {
+                            error!(error = ?e);
+                            StatusCode::INTERNAL_SERVER_ERROR
+                        })?,
+                    );
+                }
+
+                let body_content = tokio::task::spawn_blocking(move || {
+                    serde_json::to_vec(&body).map_err(|e| {
+                        error!(error = ?e);
+                        StatusCode::INTERNAL_SERVER_ERROR
+                    })
+                })
+                .await
+                .unwrap()?;
+                response.body(Body::from(body_content))
+            }
+        },
+        Err(_) => {
+            // Application code returned an error. This should not happen, as the implementation should
+            // return a valid response.
+            response.status(500).body(Body::empty())
+        }
+    };
+
+    resp.map_err(|e| {
+        error!(error = ?e);
+        StatusCode::INTERNAL_SERVER_ERROR
+    })
+}

samples/server/petstore/rust-axum/output/rust-axum-oneof/src/tests.rs

@@ -0,0 +1,101 @@
+#[test]
+fn test_oneof_schema_with_discriminator() {
+    use crate::models::*;
+
+    let test0 = r#"{"op": "ignored", "d": {"welcome_message": "test0"}}"#;
+
+    let test1 = r#"{"op": "Hello", "d": {"welcome_message": "test1"}}"#;
+    let test2 = r#"{"op": "Greeting", "d": {"greet_message": "test2"}}"#;
+    let test3 = r#"{"op": "Goodbye", "d": {"goodbye_message": "test3"}}"#;
+
+    let test4 = Hello {
+        op: "ignored".to_string(),
+        d: HelloD {
+            welcome_message: "test4".to_string(),
+        },
+    };
+
+    let test5 = Greeting {
+        op: "ignored".to_string(),
+        d: GreetingD {
+            greet_message: "test5".to_string(),
+        },
+    };
+
+    let test6 = Goodbye {
+        op: "ignored".to_string(),
+        d: GoodbyeD {
+            goodbye_message: "test6".to_string(),
+        },
+    };
+
+    let test7 = Message::Hello(test4.clone().into());
+    let test8 = Message::Greeting(test5.clone().into());
+    let test9 = Message::Goodbye(test6.clone().into());
+
+    let test10: Message = test4.clone().into();
+    let test11: Message = test5.clone().into();
+    let test12: Message = test6.clone().into();
+
+    let test13 = r#"{"op":"Hello","d":{"welcome_message":"test4"}}"#;
+    let test14 = r#"{"d":{"greet_message":"test5"},"op":"Greeting"}"#;
+    let test15 = r#"{"op":"Goodbye","d":{"goodbye_message":"test6"}}"#;
+
+    assert!(serde_json::from_str::<Message>(test0).is_err());
+
+    assert!(serde_json::from_str::<Hello>(test0).is_ok());
+    assert!(serde_json::from_str::<Greeting>(test0).is_err());
+    assert!(serde_json::from_str::<Goodbye>(test0).is_err());
+
+    assert!(serde_json::from_str::<Message>(test1).is_ok());
+    assert!(serde_json::from_str::<Message>(test2).is_ok());
+    assert!(serde_json::from_str::<Message>(test3).is_ok());
+
+    assert!(serde_json::from_str::<Hello>(test1).is_ok());
+    assert!(serde_json::from_str::<Greeting>(test2).is_ok());
+    assert!(serde_json::from_str::<Message>(test3).is_ok());
+
+    assert_eq!(
+        serde_json::to_string(&test4).expect("Serialization error"),
+        test13
+    );
+    assert_eq!(
+        serde_json::to_string(&test5).expect("Serialization error"),
+        test14
+    );
+    assert_eq!(
+        serde_json::to_string(&test6).expect("Serialization error"),
+        test15
+    );
+
+    assert_eq!(
+        serde_json::to_string(&test7).expect("Serialization error"),
+        test13
+    );
+    assert_eq!(
+        serde_json::to_string(&test8).expect("Serialization error"),
+        test14
+    );
+    assert_eq!(
+        serde_json::to_string(&test9).expect("Serialization error"),
+        test15
+    );
+
+    assert_eq!(
+        serde_json::to_string(&test10).expect("Serialization error"),
+        test13
+    );
+    assert_eq!(
+        serde_json::to_string(&test11).expect("Serialization error"),
+        test14
+    );
+    assert_eq!(
+        serde_json::to_string(&test12).expect("Serialization error"),
+        test15
+    );
+}
+
+#[tokio::test]
+async fn tokio_test() {
+    assert!(true);
+}

samples/server/petstore/rust-axum/output/rust-axum-oneof/src/types.rs

@@ -0,0 +1,790 @@
+use std::{mem, str::FromStr};
+
+use base64::{engine::general_purpose, Engine};
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
+
+#[derive(Debug, Clone, PartialEq, serde::Serialize, serde::Deserialize)]
+#[allow(dead_code)]
+pub struct Object(serde_json::Value);
+
+impl validator::Validate for Object {
+    fn validate(&self) -> Result<(), validator::ValidationErrors> {
+        Ok(())
+    }
+}
+
+impl FromStr for Object {
+    type Err = String;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Ok(Self(serde_json::Value::String(s.to_owned())))
+    }
+}
+
+/// Serde helper function to create a default `Option<Nullable<T>>` while
+/// deserializing
+pub fn default_optional_nullable<T>() -> Option<Nullable<T>> {
+    None
+}
+
+/// Serde helper function to deserialize into an `Option<Nullable<T>>`
+pub fn deserialize_optional_nullable<'de, D, T>(
+    deserializer: D,
+) -> Result<Option<Nullable<T>>, D::Error>
+where
+    D: Deserializer<'de>,
+    T: Deserialize<'de>,
+{
+    Option::<T>::deserialize(deserializer).map(|val| match val {
+        Some(inner) => Some(Nullable::Present(inner)),
+        None => Some(Nullable::Null),
+    })
+}
+
+/// The Nullable type. Represents a value which may be specified as null on an API.
+/// Note that this is distinct from a value that is optional and not present!
+///
+/// Nullable implements many of the same methods as the Option type (map, unwrap, etc).
+#[derive(Debug, Clone, Copy, PartialEq, PartialOrd)]
+pub enum Nullable<T> {
+    /// Null value
+    Null,
+    /// Value is present
+    Present(T),
+}
+
+impl<T> Nullable<T> {
+    /////////////////////////////////////////////////////////////////////////
+    // Querying the contained values
+    /////////////////////////////////////////////////////////////////////////
+
+    /// Returns `true` if the Nullable is a `Present` value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let x: Nullable<u32> = Nullable::Present(2);
+    /// assert_eq!(x.is_present(), true);
+    ///
+    /// let x: Nullable<u32> = Nullable::Null;
+    /// assert_eq!(x.is_present(), false);
+    /// ```
+    #[inline]
+    pub fn is_present(&self) -> bool {
+        match *self {
+            Nullable::Present(_) => true,
+            Nullable::Null => false,
+        }
+    }
+
+    /// Returns `true` if the Nullable is a `Null` value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let x: Nullable<u32> = Nullable::Present(2);
+    /// assert_eq!(x.is_null(), false);
+    ///
+    /// let x: Nullable<u32> = Nullable::Null;
+    /// assert_eq!(x.is_null(), true);
+    /// ```
+    #[inline]
+    pub fn is_null(&self) -> bool {
+        !self.is_present()
+    }
+
+    /////////////////////////////////////////////////////////////////////////
+    // Adapter for working with references
+    /////////////////////////////////////////////////////////////////////////
+
+    /// Converts from `Nullable<T>` to `Nullable<&T>`.
+    ///
+    /// # Examples
+    ///
+    /// Convert an `Nullable<`[`String`]`>` into a `Nullable<`[`usize`]`>`, preserving the original.
+    /// The [`map`] method takes the `self` argument by value, consuming the original,
+    /// so this technique uses `as_ref` to first take a `Nullable` to a reference
+    /// to the value inside the original.
+    ///
+    /// [`map`]: enum.Nullable.html#method.map
+    /// [`String`]: ../../std/string/struct.String.html
+    /// [`usize`]: ../../std/primitive.usize.html
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let num_as_str: Nullable<String> = Nullable::Present("10".to_string());
+    /// // First, cast `Nullable<String>` to `Nullable<&String>` with `as_ref`,
+    /// // then consume *that* with `map`, leaving `num_as_str` on the stack.
+    /// let num_as_int: Nullable<usize> = num_as_str.as_ref().map(|n| n.len());
+    /// println!("still can print num_as_str: {:?}", num_as_str);
+    /// ```
+    #[inline]
+    pub fn as_ref(&self) -> Nullable<&T> {
+        match *self {
+            Nullable::Present(ref x) => Nullable::Present(x),
+            Nullable::Null => Nullable::Null,
+        }
+    }
+
+    /// Converts from `Nullable<T>` to `Nullable<&mut T>`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let mut x = Nullable::Present(2);
+    /// match x.as_mut() {
+    ///     Nullable::Present(v) => *v = 42,
+    ///     Nullable::Null => {},
+    /// }
+    /// assert_eq!(x, Nullable::Present(42));
+    /// ```
+    #[inline]
+    pub fn as_mut(&mut self) -> Nullable<&mut T> {
+        match *self {
+            Nullable::Present(ref mut x) => Nullable::Present(x),
+            Nullable::Null => Nullable::Null,
+        }
+    }
+
+    /////////////////////////////////////////////////////////////////////////
+    // Getting to contained values
+    /////////////////////////////////////////////////////////////////////////
+
+    /// Unwraps a Nullable, yielding the content of a `Nullable::Present`.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the value is a [`Nullable::Null`] with a custom panic message provided by
+    /// `msg`.
+    ///
+    /// [`Nullable::Null`]: #variant.Null
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let x = Nullable::Present("value");
+    /// assert_eq!(x.expect("the world is ending"), "value");
+    /// ```
+    ///
+    /// ```should_panic
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let x: Nullable<&str> = Nullable::Null;
+    /// x.expect("the world is ending"); // panics with `the world is ending`
+    /// ```
+    #[inline]
+    pub fn expect(self, msg: &str) -> T {
+        match self {
+            Nullable::Present(val) => val,
+            Nullable::Null => expect_failed(msg),
+        }
+    }
+
+    /// Moves the value `v` out of the `Nullable<T>` if it is `Nullable::Present(v)`.
+    ///
+    /// In general, because this function may panic, its use is discouraged.
+    /// Instead, prefer to use pattern matching and handle the `Nullable::Null`
+    /// case explicitly.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the self value equals [`Nullable::Null`].
+    ///
+    /// [`Nullable::Null`]: #variant.Null
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let x = Nullable::Present("air");
+    /// assert_eq!(x.unwrap(), "air");
+    /// ```
+    ///
+    /// ```should_panic
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let x: Nullable<&str> = Nullable::Null;
+    /// assert_eq!(x.unwrap(), "air"); // fails
+    /// ```
+    #[inline]
+    pub fn unwrap(self) -> T {
+        match self {
+            Nullable::Present(val) => val,
+            Nullable::Null => panic!("called `Nullable::unwrap()` on a `Nullable::Null` value"),
+        }
+    }
+
+    /// Returns the contained value or a default.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// assert_eq!(Nullable::Present("car").unwrap_or("bike"), "car");
+    /// assert_eq!(Nullable::Null.unwrap_or("bike"), "bike");
+    /// ```
+    #[inline]
+    pub fn unwrap_or(self, def: T) -> T {
+        match self {
+            Nullable::Present(x) => x,
+            Nullable::Null => def,
+        }
+    }
+
+    /// Returns the contained value or computes it from a closure.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let k = 10;
+    /// assert_eq!(Nullable::Present(4).unwrap_or_else(|| 2 * k), 4);
+    /// assert_eq!(Nullable::Null.unwrap_or_else(|| 2 * k), 20);
+    /// ```
+    #[inline]
+    pub fn unwrap_or_else<F: FnOnce() -> T>(self, f: F) -> T {
+        match self {
+            Nullable::Present(x) => x,
+            Nullable::Null => f(),
+        }
+    }
+
+    /////////////////////////////////////////////////////////////////////////
+    // Transforming contained values
+    /////////////////////////////////////////////////////////////////////////
+
+    /// Maps a `Nullable<T>` to `Nullable<U>` by applying a function to a contained value.
+    ///
+    /// # Examples
+    ///
+    /// Convert a `Nullable<`[`String`]`>` into a `Nullable<`[`usize`]`>`, consuming the original:
+    ///
+    /// [`String`]: ../../std/string/struct.String.html
+    /// [`usize`]: ../../std/primitive.usize.html
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let maybe_some_string = Nullable::Present(String::from("Hello, World!"));
+    /// // `Nullable::map` takes self *by value*, consuming `maybe_some_string`
+    /// let maybe_some_len = maybe_some_string.map(|s| s.len());
+    ///
+    /// assert_eq!(maybe_some_len, Nullable::Present(13));
+    /// ```
+    #[inline]
+    pub fn map<U, F: FnOnce(T) -> U>(self, f: F) -> Nullable<U> {
+        match self {
+            Nullable::Present(x) => Nullable::Present(f(x)),
+            Nullable::Null => Nullable::Null,
+        }
+    }
+
+    /// Applies a function to the contained value (if any),
+    /// or returns a `default` (if not).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let x = Nullable::Present("foo");
+    /// assert_eq!(x.map_or(42, |v| v.len()), 3);
+    ///
+    /// let x: Nullable<&str> = Nullable::Null;
+    /// assert_eq!(x.map_or(42, |v| v.len()), 42);
+    /// ```
+    #[inline]
+    pub fn map_or<U, F: FnOnce(T) -> U>(self, default: U, f: F) -> U {
+        match self {
+            Nullable::Present(t) => f(t),
+            Nullable::Null => default,
+        }
+    }
+
+    /// Applies a function to the contained value (if any),
+    /// or computes a `default` (if not).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let k = 21;
+    ///
+    /// let x = Nullable::Present("foo");
+    /// assert_eq!(x.map_or_else(|| 2 * k, |v| v.len()), 3);
+    ///
+    /// let x: Nullable<&str> = Nullable::Null;
+    /// assert_eq!(x.map_or_else(|| 2 * k, |v| v.len()), 42);
+    /// ```
+    #[inline]
+    pub fn map_or_else<U, D: FnOnce() -> U, F: FnOnce(T) -> U>(self, default: D, f: F) -> U {
+        match self {
+            Nullable::Present(t) => f(t),
+            Nullable::Null => default(),
+        }
+    }
+
+    /// Transforms the `Nullable<T>` into a [`Result<T, E>`], mapping `Nullable::Present(v)` to
+    /// [`Ok(v)`] and `Nullable::Null` to [`Err(err)`][Err].
+    ///
+    /// [`Result<T, E>`]: ../../std/result/enum.Result.html
+    /// [`Ok(v)`]: ../../std/result/enum.Result.html#variant.Ok
+    /// [Err]: ../../std/result/enum.Result.html#variant.Err
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let x = Nullable::Present("foo");
+    /// assert_eq!(x.ok_or(0), Ok("foo"));
+    ///
+    /// let x: Nullable<&str> = Nullable::Null;
+    /// assert_eq!(x.ok_or(0), Err(0));
+    /// ```
+    #[inline]
+    pub fn ok_or<E>(self, err: E) -> Result<T, E> {
+        match self {
+            Nullable::Present(v) => Ok(v),
+            Nullable::Null => Err(err),
+        }
+    }
+
+    /// Transforms the `Nullable<T>` into a [`Result<T, E>`], mapping `Nullable::Present(v)` to
+    /// [`Ok(v)`] and `Nullable::Null` to [`Err(err())`][Err].
+    ///
+    /// [`Result<T, E>`]: ../../std/result/enum.Result.html
+    /// [`Ok(v)`]: ../../std/result/enum.Result.html#variant.Ok
+    /// [Err]: ../../std/result/enum.Result.html#variant.Err
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let x = Nullable::Present("foo");
+    /// assert_eq!(x.ok_or_else(|| 0), Ok("foo"));
+    ///
+    /// let x: Nullable<&str> = Nullable::Null;
+    /// assert_eq!(x.ok_or_else(|| 0), Err(0));
+    /// ```
+    #[inline]
+    pub fn ok_or_else<E, F: FnOnce() -> E>(self, err: F) -> Result<T, E> {
+        match self {
+            Nullable::Present(v) => Ok(v),
+            Nullable::Null => Err(err()),
+        }
+    }
+
+    /////////////////////////////////////////////////////////////////////////
+    // Boolean operations on the values, eager and lazy
+    /////////////////////////////////////////////////////////////////////////
+
+    /// Returns `Nullable::Null` if the Nullable is `Nullable::Null`, otherwise returns `optb`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let x = Nullable::Present(2);
+    /// let y: Nullable<&str> = Nullable::Null;
+    /// assert_eq!(x.and(y), Nullable::Null);
+    ///
+    /// let x: Nullable<u32> = Nullable::Null;
+    /// let y = Nullable::Present("foo");
+    /// assert_eq!(x.and(y), Nullable::Null);
+    ///
+    /// let x = Nullable::Present(2);
+    /// let y = Nullable::Present("foo");
+    /// assert_eq!(x.and(y), Nullable::Present("foo"));
+    ///
+    /// let x: Nullable<u32> = Nullable::Null;
+    /// let y: Nullable<&str> = Nullable::Null;
+    /// assert_eq!(x.and(y), Nullable::Null);
+    /// ```
+    #[inline]
+    pub fn and<U>(self, optb: Nullable<U>) -> Nullable<U> {
+        match self {
+            Nullable::Present(_) => optb,
+            Nullable::Null => Nullable::Null,
+        }
+    }
+
+    /// Returns `Nullable::Null` if the Nullable is `Nullable::Null`, otherwise calls `f` with the
+    /// wrapped value and returns the result.
+    ///
+    /// Some languages call this operation flatmap.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// fn sq(x: u32) -> Nullable<u32> { Nullable::Present(x * x) }
+    /// fn nope(_: u32) -> Nullable<u32> { Nullable::Null }
+    ///
+    /// assert_eq!(Nullable::Present(2).and_then(sq).and_then(sq), Nullable::Present(16));
+    /// assert_eq!(Nullable::Present(2).and_then(sq).and_then(nope), Nullable::Null);
+    /// assert_eq!(Nullable::Present(2).and_then(nope).and_then(sq), Nullable::Null);
+    /// assert_eq!(Nullable::Null.and_then(sq).and_then(sq), Nullable::Null);
+    /// ```
+    #[inline]
+    pub fn and_then<U, F: FnOnce(T) -> Nullable<U>>(self, f: F) -> Nullable<U> {
+        match self {
+            Nullable::Present(x) => f(x),
+            Nullable::Null => Nullable::Null,
+        }
+    }
+
+    /// Returns the Nullable if it contains a value, otherwise returns `optb`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let x = Nullable::Present(2);
+    /// let y = Nullable::Null;
+    /// assert_eq!(x.or(y), Nullable::Present(2));
+    ///
+    /// let x = Nullable::Null;
+    /// let y = Nullable::Present(100);
+    /// assert_eq!(x.or(y), Nullable::Present(100));
+    ///
+    /// let x = Nullable::Present(2);
+    /// let y = Nullable::Present(100);
+    /// assert_eq!(x.or(y), Nullable::Present(2));
+    ///
+    /// let x: Nullable<u32> = Nullable::Null;
+    /// let y = Nullable::Null;
+    /// assert_eq!(x.or(y), Nullable::Null);
+    /// ```
+    #[inline]
+    pub fn or(self, optb: Nullable<T>) -> Nullable<T> {
+        match self {
+            Nullable::Present(_) => self,
+            Nullable::Null => optb,
+        }
+    }
+
+    /// Returns the Nullable if it contains a value, otherwise calls `f` and
+    /// returns the result.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// fn nobody() -> Nullable<&'static str> { Nullable::Null }
+    /// fn vikings() -> Nullable<&'static str> { Nullable::Present("vikings") }
+    ///
+    /// assert_eq!(Nullable::Present("barbarians").or_else(vikings),
+    ///            Nullable::Present("barbarians"));
+    /// assert_eq!(Nullable::Null.or_else(vikings), Nullable::Present("vikings"));
+    /// assert_eq!(Nullable::Null.or_else(nobody), Nullable::Null);
+    /// ```
+    #[inline]
+    pub fn or_else<F: FnOnce() -> Nullable<T>>(self, f: F) -> Nullable<T> {
+        match self {
+            Nullable::Present(_) => self,
+            Nullable::Null => f(),
+        }
+    }
+
+    /////////////////////////////////////////////////////////////////////////
+    // Misc
+    /////////////////////////////////////////////////////////////////////////
+
+    /// Takes the value out of the Nullable, leaving a `Nullable::Null` in its place.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let mut x = Nullable::Present(2);
+    /// x.take();
+    /// assert_eq!(x, Nullable::Null);
+    ///
+    /// let mut x: Nullable<u32> = Nullable::Null;
+    /// x.take();
+    /// assert_eq!(x, Nullable::Null);
+    /// ```
+    #[inline]
+    pub fn take(&mut self) -> Nullable<T> {
+        mem::replace(self, Nullable::Null)
+    }
+}
+
+impl<T: Clone> Nullable<&T> {
+    /// Maps an `Nullable<&T>` to an `Nullable<T>` by cloning the contents of the
+    /// Nullable.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let x = 12;
+    /// let opt_x = Nullable::Present(&x);
+    /// assert_eq!(opt_x, Nullable::Present(&12));
+    /// let cloned = opt_x.cloned();
+    /// assert_eq!(cloned, Nullable::Present(12));
+    /// ```
+    pub fn cloned(self) -> Nullable<T> {
+        self.map(Clone::clone)
+    }
+}
+
+impl<T: Default> Nullable<T> {
+    /// Returns the contained value or a default
+    ///
+    /// Consumes the `self` argument then, if `Nullable::Present`, returns the contained
+    /// value, otherwise if `Nullable::Null`, returns the default value for that
+    /// type.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use rust_axum_oneof::types::Nullable;
+    ///
+    /// let x = Nullable::Present(42);
+    /// assert_eq!(42, x.unwrap_or_default());
+    ///
+    /// let y: Nullable<i32> = Nullable::Null;
+    /// assert_eq!(0, y.unwrap_or_default());
+    /// ```
+    #[inline]
+    pub fn unwrap_or_default(self) -> T {
+        match self {
+            Nullable::Present(x) => x,
+            Nullable::Null => Default::default(),
+        }
+    }
+}
+
+impl<T> Default for Nullable<T> {
+    /// Returns None.
+    #[inline]
+    fn default() -> Nullable<T> {
+        Nullable::Null
+    }
+}
+
+impl<T> From<T> for Nullable<T> {
+    fn from(val: T) -> Nullable<T> {
+        Nullable::Present(val)
+    }
+}
+
+impl<T> Serialize for Nullable<T>
+where
+    T: Serialize,
+{
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        match *self {
+            Nullable::Present(ref inner) => serializer.serialize_some(&inner),
+            Nullable::Null => serializer.serialize_none(),
+        }
+    }
+}
+
+impl<'de, T> Deserialize<'de> for Nullable<T>
+where
+    T: serde::de::DeserializeOwned,
+{
+    fn deserialize<D>(deserializer: D) -> Result<Nullable<T>, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        // In order to deserialize a required, but nullable, value, we first have to check whether
+        // the value is present at all. To do this, we deserialize to a serde_json::Value, which
+        // fails if the value is missing, or gives serde_json::Value::Null if the value is present.
+        // If that succeeds as null, we can easily return a Null.
+        // If that succeeds as some value, we deserialize that value and return a Present.
+        // If that errors, we return the error.
+        let presence: Result<::serde_json::Value, _> =
+            serde::Deserialize::deserialize(deserializer);
+        match presence {
+            Ok(serde_json::Value::Null) => Ok(Nullable::Null),
+            Ok(some_value) => serde_json::from_value(some_value)
+                .map(Nullable::Present)
+                .map_err(serde::de::Error::custom),
+            Err(x) => Err(x),
+        }
+    }
+}
+
+impl<T> validator::Validate for Nullable<T>
+where
+    T: validator::Validate,
+{
+    fn validate(&self) -> Result<(), validator::ValidationErrors> {
+        match self {
+            Self::Present(x) => x.validate(),
+            Self::Null => Ok(()),
+        }
+    }
+}
+
+impl<'a, T> validator::ValidateArgs<'a> for Nullable<T>
+where
+    T: validator::ValidateArgs<'a>,
+{
+    type Args = T::Args;
+    fn validate_with_args(&self, args: Self::Args) -> Result<(), validator::ValidationErrors> {
+        match self {
+            Self::Present(x) => x.validate_with_args(args),
+            Self::Null => Ok(()),
+        }
+    }
+}
+
+impl<T> validator::ValidateEmail for Nullable<T>
+where
+    T: validator::ValidateEmail,
+{
+    fn as_email_string(&self) -> Option<std::borrow::Cow<str>> {
+        match self {
+            Self::Present(x) => x.as_email_string(),
+            Self::Null => None,
+        }
+    }
+}
+
+impl<T> validator::ValidateUrl for Nullable<T>
+where
+    T: validator::ValidateUrl,
+{
+    fn as_url_string(&self) -> Option<std::borrow::Cow<str>> {
+        match self {
+            Self::Present(x) => x.as_url_string(),
+            Self::Null => None,
+        }
+    }
+}
+
+impl<T> validator::ValidateContains for Nullable<T>
+where
+    T: validator::ValidateContains,
+{
+    fn validate_contains(&self, needle: &str) -> bool {
+        match self {
+            Self::Present(x) => x.validate_contains(needle),
+            Self::Null => true,
+        }
+    }
+}
+
+impl<T> validator::ValidateRequired for Nullable<T>
+where
+    T: validator::ValidateRequired,
+{
+    fn is_some(&self) -> bool {
+        self.is_present()
+    }
+}
+
+impl<T> validator::ValidateRegex for Nullable<T>
+where
+    T: validator::ValidateRegex,
+{
+    fn validate_regex(&self, regex: impl validator::AsRegex) -> bool {
+        match self {
+            Self::Present(x) => x.validate_regex(regex),
+            Self::Null => true,
+        }
+    }
+}
+
+impl<T, I> validator::ValidateRange<I> for Nullable<T>
+where
+    T: validator::ValidateRange<I>,
+{
+    fn greater_than(&self, max: I) -> Option<bool> {
+        use validator::ValidateRange;
+        match self {
+            Self::Present(x) => x.greater_than(max),
+            Self::Null => None,
+        }
+    }
+    fn less_than(&self, min: I) -> Option<bool> {
+        use validator::ValidateRange;
+        match self {
+            Self::Present(x) => x.less_than(min),
+            Self::Null => None,
+        }
+    }
+}
+
+impl<T, I> validator::ValidateLength<I> for Nullable<T>
+where
+    T: validator::ValidateLength<I>,
+    I: PartialEq + PartialOrd,
+{
+    fn length(&self) -> Option<I> {
+        use validator::ValidateLength;
+        match self {
+            Self::Present(x) => x.length(),
+            Self::Null => None,
+        }
+    }
+}
+
+impl<T> From<Nullable<T>> for Option<T> {
+    fn from(value: Nullable<T>) -> Option<T> {
+        match value {
+            Nullable::Present(x) => Some(x),
+            Nullable::Null => None,
+        }
+    }
+}
+
+#[inline(never)]
+#[cold]
+fn expect_failed(msg: &str) -> ! {
+    panic!("{}", msg)
+}
+
+#[derive(Debug, Clone, PartialEq, PartialOrd)]
+/// Base64-encoded byte array
+pub struct ByteArray(pub Vec<u8>);
+
+impl Serialize for ByteArray {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        serializer.serialize_str(&general_purpose::STANDARD.encode(&self.0))
+    }
+}
+
+impl<'de> Deserialize<'de> for ByteArray {
+    fn deserialize<D>(deserializer: D) -> Result<ByteArray, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let s = String::deserialize(deserializer)?;
+        match general_purpose::STANDARD.decode(s) {
+            Ok(bin) => Ok(ByteArray(bin)),
+            _ => Err(serde::de::Error::custom("invalid base64")),
+        }
+    }
+}

samples/server/petstore/rust-axum/output/rust-axum-test/.openapi-generator/FILES

@@ -7,4 +7,5 @@ src/header.rs
 src/lib.rs
 src/models.rs
 src/server/mod.rs
+src/tests.rs
 src/types.rs

samples/server/petstore/rust-axum/output/rust-axum-test/src/lib.rs

@@ -26,3 +26,6 @@ pub mod types;
 
 #[cfg(feature = "server")]
 pub(crate) mod header;
+
+#[cfg(test)]
+mod tests;

samples/server/petstore/rust-axum/output/rust-axum-test/src/tests.rs

@@ -0,0 +1,9 @@
+#[test]
+fn std_test() {
+    assert!(true);
+}
+
+#[tokio::test]
+async fn tokio_test() {
+    assert!(true);
+}

samples/server/petstore/rust-axum/output/rust-axum-validation-test/.openapi-generator/FILES

@@ -7,4 +7,5 @@ src/header.rs
 src/lib.rs
 src/models.rs
 src/server/mod.rs
+src/tests.rs
 src/types.rs

samples/server/petstore/rust-axum/output/rust-axum-validation-test/src/lib.rs

@@ -26,3 +26,6 @@ pub mod types;
 
 #[cfg(feature = "server")]
 pub(crate) mod header;
+
+#[cfg(test)]
+mod tests;

samples/server/petstore/rust-axum/output/rust-axum-validation-test/src/tests.rs

@@ -0,0 +1,9 @@
+#[test]
+fn std_test() {
+    assert!(true);
+}
+
+#[tokio::test]
+async fn tokio_test() {
+    assert!(true);
+}