From 618f4bdd39ce740edca75fa2e9db93656d54ca33 Mon Sep 17 00:00:00 2001
From: Jim Schubert <james.schubert@gmail.com>
Date: Sat, 7 May 2016 22:22:48 -0400
Subject: [PATCH] [csharp] Constructor handling for serialization

Resolving an issue with serializing classes that contain required
properties. When the only constructor has defaulted parameters, no
parameterless constructor is generated but JSON.Net attempts to call
the missing constructor on deserialization (because of DataContract).

See: https://manski.net/2014/10/net-serializers-comparison-chart/

The fix here is to create a protected constructor, annotate it with
JsonConstructorAttribute to inform JSON.Net it is the constructor to use
during serialization, then provide settings that explicitly allow
JSON.Net to access non-public constructors during serialiazation.
---
 .../src/main/java/io/swagger/codegen/CodegenModel.java     | 2 +-
 .../src/main/java/io/swagger/codegen/DefaultCodegen.java   | 2 ++
 .../src/main/resources/csharp/ApiClient.mustache           | 7 ++++++-
 .../src/main/resources/csharp/modelGeneric.mustache        | 7 +++++++
 4 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenModel.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenModel.java
index ccea2ee070e9..438eb1912946 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenModel.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenModel.java
@@ -27,7 +27,7 @@ public class CodegenModel {
     public Set<String> allMandatory;
 
     public Set<String> imports = new TreeSet<String>();
-    public Boolean hasVars, emptyVars, hasMoreModels, hasEnums, isEnum;
+    public Boolean hasVars, emptyVars, hasMoreModels, hasEnums, isEnum, hasRequired;
     public ExternalDocs externalDocs;
 
     public Map<String, Object> vendorExtensions;
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java
index db000e9c63ed..abe9dbea04ef 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java
@@ -2432,6 +2432,7 @@ public class DefaultCodegen {
     private void addVars(CodegenModel m, Map<String, Property> properties, List<String> required,
             Map<String, Property> allProperties, List<String> allRequired) {
 
+        m.hasRequired = false;
         if (properties != null && !properties.isEmpty()) {
             m.hasVars = true;
             m.hasEnums = false;
@@ -2470,6 +2471,7 @@ public class DefaultCodegen {
             } else {
                 final CodegenProperty cp = fromProperty(key, prop);
                 cp.required = mandatory.contains(key) ? true : null;
+                m.hasRequired = Boolean.TRUE.equals(m.hasRequired) || Boolean.TRUE.equals(cp.required);
                 if (cp.isEnum) {
                     // FIXME: if supporting inheritance, when called a second time for allProperties it is possible for
                     // m.hasEnums to be set incorrectly if allProperties has enumerations but properties does not.
diff --git a/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache b/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache
index 2c0f8f681e38..f9b9f7662999 100644
--- a/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache
+++ b/modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache
@@ -20,6 +20,11 @@ namespace {{packageName}}.Client
     /// </summary>
     public class ApiClient
     {
+        private JsonSerializerSettings serializerSettings = new JsonSerializerSettings
+        {
+            ConstructorHandling = ConstructorHandling.AllowNonPublicDefaultConstructor
+        };
+
         /// <summary>
         /// Initializes a new instance of the <see cref="ApiClient" /> class
         /// with default configuration and base path ({{basePath}}).
@@ -305,7 +310,7 @@ namespace {{packageName}}.Client
             // at this point, it must be a model (json)
             try
             {
-                return JsonConvert.DeserializeObject(response.Content, type);
+                return JsonConvert.DeserializeObject(response.Content, type, serializerSettings);
             }
             catch (Exception e)
             {
diff --git a/modules/swagger-codegen/src/main/resources/csharp/modelGeneric.mustache b/modules/swagger-codegen/src/main/resources/csharp/modelGeneric.mustache
index 6c5da5e4f56b..ebadaf2046ae 100644
--- a/modules/swagger-codegen/src/main/resources/csharp/modelGeneric.mustache
+++ b/modules/swagger-codegen/src/main/resources/csharp/modelGeneric.mustache
@@ -24,6 +24,13 @@
         public {{{datatypeWithEnum}}}{{#isEnum}}?{{/isEnum}} {{name}} { get; set; }
         {{/isEnum}}
         {{/vars}}
+    {{#hasRequired}}
+        /// <summary>
+        /// Initializes a new instance of the <see cref="{{classname}}" /> class.
+        /// </summary>
+        [JsonConstructorAttribute]
+        protected {{classname}}() { }
+    {{/hasRequired}}
         /// <summary>
         /// Initializes a new instance of the <see cref="{{classname}}" /> class.
         /// </summary>