Feature optional emit default values (#4347)

* This commit addresses issue #4346 and adds the proposed optionalEmitDefaultValues flag.

* ran /bin/cshapr-netcore-petstore.sh to create sample clients

* Fixed lost newline

* Ran script again to update samples

Author: Valentin-Tintin

docs/generators/csharp-netcore.md

@@ -19,6 +19,7 @@ sidebar_label: csharp-netcore
 |returnICollection|Return ICollection<T> instead of the concrete type.| |false|
 |optionalMethodArgument|C# Optional method argument, e.g. void square(int x=10) (.net 4.0+ only).| |true|
 |optionalAssemblyInfo|Generate AssemblyInfo.cs.| |true|
+|optionalEmitDefaultValues|Set DataMember's EmitDefaultValue.| |false|
 |optionalProjectFile|Generate {PackageName}.csproj.| |true|
 |nonPublicApi|Generates code with reduced access modifiers; allows embedding elsewhere without exposing non-public API calls to consumers.| |false|
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|

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

@@ -185,6 +185,10 @@ public CSharpNetCoreClientCodegen() {
                 CodegenConstants.OPTIONAL_ASSEMBLY_INFO_DESC,
                 this.optionalAssemblyInfoFlag);
 
+        addSwitch(CodegenConstants.OPTIONAL_EMIT_DEFAULT_VALUES,
+                CodegenConstants.OPTIONAL_EMIT_DEFAULT_VALUES_DESC,
+                this.optionalEmitDefaultValuesFlag);
+
         addSwitch(CodegenConstants.OPTIONAL_PROJECT_FILE,
                 CodegenConstants.OPTIONAL_PROJECT_FILE_DESC,
                 this.optionalProjectFileFlag);
@@ -370,6 +374,8 @@ public String modelTestFileFolder() {
     @Override
     public void postProcessModelProperty(CodegenModel model, CodegenProperty property) {
         postProcessPattern(property.pattern, property.vendorExtensions);
+        postProcessEmitDefaultValue(property.vendorExtensions);
+
         super.postProcessModelProperty(model, property);
     }
 
@@ -403,6 +409,7 @@ public Map<String, Object> postProcessOperationsWithModels(Map<String, Object> o
     @Override
     public void postProcessParameter(CodegenParameter parameter) {
         postProcessPattern(parameter.pattern, parameter.vendorExtensions);
+        postProcessEmitDefaultValue(parameter.vendorExtensions);
         super.postProcessParameter(parameter);
 
         if (!parameter.required && nullableType.contains(parameter.dataType)) { //optional
@@ -446,6 +453,10 @@ public void postProcessPattern(String pattern, Map<String, Object> vendorExtensi
         }
     }
 
+    public void postProcessEmitDefaultValue(Map<String, Object> vendorExtensions) {
+        vendorExtensions.put("x-emit-default-value", optionalEmitDefaultValuesFlag);
+    }
+
     @Override
     public Mustache.Compiler processCompiler(Mustache.Compiler compiler) {
         // To avoid unexpected behaviors when options are passed programmatically such as { "supportsAsync": "" }
@@ -465,6 +476,13 @@ public void processOpts() {
          *     if (additionalProperties.containsKey(prop)) convertPropertyToBooleanAndWriteBack(prop);
          */
 
+        if (additionalProperties.containsKey(CodegenConstants.OPTIONAL_EMIT_DEFAULT_VALUES)) {
+            setOptionalEmitDefaultValuesFlag(convertPropertyToBooleanAndWriteBack(CodegenConstants.OPTIONAL_EMIT_DEFAULT_VALUES));
+        } else {
+            additionalProperties.put(CodegenConstants.OPTIONAL_EMIT_DEFAULT_VALUES, optionalEmitDefaultValuesFlag);
+        }
+
+
         if (additionalProperties.containsKey(CodegenConstants.MODEL_PROPERTY_NAMING)) {
             setModelPropertyNaming((String) additionalProperties.get(CodegenConstants.MODEL_PROPERTY_NAMING));
         }
@@ -610,6 +628,10 @@ public void setOptionalAssemblyInfoFlag(boolean flag) {
         this.optionalAssemblyInfoFlag = flag;
     }
 
+    public void setOptionalEmitDefaultValuesFlag(boolean flag){
+        this.optionalEmitDefaultValuesFlag = flag;
+    }
+
     public void setOptionalProjectFileFlag(boolean flag) {
         this.optionalProjectFileFlag = flag;
     }

modules/openapi-generator/src/main/resources/csharp-netcore/modelGeneric.mustache

@@ -33,7 +33,7 @@
         {{#description}}
         /// <value>{{description}}</value>
         {{/description}}
-        [DataMember(Name="{{baseName}}", EmitDefaultValue={{#isNullable}}true{{/isNullable}}{{^isNullable}}false{{/isNullable}})]
+        [DataMember(Name="{{baseName}}", EmitDefaultValue={{#vendorExtensions.x-emit-default-value}}true{{/vendorExtensions.x-emit-default-value}}{{^vendorExtensions.x-emit-default-value}}{{#isNullable}}true{{/isNullable}}{{^isNullable}}false{{/isNullable}}{{/vendorExtensions.x-emit-default-value}})]
         public {{#complexType}}{{{complexType}}}{{/complexType}}{{^complexType}}{{{datatypeWithEnum}}}{{/complexType}}{{^isContainer}}{{^required}}?{{/required}}{{/isContainer}} {{name}} { get; set; }
         {{/isEnum}}
         {{/vars}}
@@ -116,7 +116,7 @@
         /// {{^description}}Gets or Sets {{{name}}}{{/description}}{{#description}}{{description}}{{/description}}
         /// </summary>{{#description}}
         /// <value>{{description}}</value>{{/description}}
-        [DataMember(Name="{{baseName}}", EmitDefaultValue={{#isNullable}}true{{/isNullable}}{{^isNullable}}false{{/isNullable}})]{{#isDate}}
+        [DataMember(Name="{{baseName}}", EmitDefaultValue={{#vendorExtensions.x-emit-default-value}}true{{/vendorExtensions.x-emit-default-value}}{{^vendorExtensions.x-emit-default-value}}{{#isNullable}}true{{/isNullable}}{{^isNullable}}false{{/isNullable}}{{/vendorExtensions.x-emit-default-value}})]{{#isDate}}
         [JsonConverter(typeof(OpenAPIDateConverter))]{{/isDate}}
         public {{{dataType}}} {{name}} { get; {{#isReadOnly}}private {{/isReadOnly}}set; }