[Go] Set Default Values for Required Variables when a default is defined (#19232)

* use default values for required vars when available

* update tests to existing config file

* cleanup OAS test

* Remove setting value in Get.

* Use Pascal Case for variable naming in Getter Function

* add a CLI option

* add a CLI option

* add a CLI option

bin/configs/go-petstore.yaml

@@ -15,6 +15,7 @@ additionalProperties:
   packageName: petstore
   disallowAdditionalPropertiesIfNotPresent: false
   generateInterfaces: true
+  useDefaultValuesForRequiredVars: "true"
 enumNameMappings:
   delivered: SHIPPED
 

docs/generators/go.md

@@ -29,6 +29,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |packageVersion|Go package version.| |1.0.0|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |structPrefix|whether to prefix struct with the class name. e.g. DeletePetOpts => PetApiDeletePetOpts| |false|
+|useDefaultValuesForRequiredVars|Use default values for required variables when available| |false|
 |useOneOfDiscriminatorLookup|Use the discriminator's mapping in oneOf to speed up the model lookup. IMPORTANT: Validation (e.g. one and only one match in oneOf's schemas) will be skipped.| |false|
 |withAWSV4Signature|whether to include AWS v4 signature support| |false|
 |withGoMod|Generate go.mod and go.sum| |true|

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

@@ -451,4 +451,6 @@ public class CodegenConstants {
     public static final String MAX_ATTEMPTS_FOR_RETRY = "maxAttemptsForRetry";
 
     public static final String WAIT_TIME_OF_THREAD = "waitTimeMillis";
+
+    public static final String USE_DEFAULT_VALUES_FOR_REQUIRED_VARS = "useDefaultValuesForRequiredVars";
 }

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

@@ -58,6 +58,8 @@ public abstract class AbstractGoCodegen extends DefaultCodegen implements Codege
     protected boolean generateMarshalJSON = true;
     @Setter
     protected boolean generateUnmarshalJSON = true;
+    @Setter
+    protected boolean useDefaultValuesForRequiredVars = false;
 
     @Setter
     protected String packageName = "openapi";

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

@@ -55,6 +55,7 @@ public class GoClientCodegen extends AbstractGoCodegen {
     public static final String GENERATE_INTERFACES = "generateInterfaces";
     public static final String MODEL_FILE_FOLDER = "modelFileFolder";
     public static final String WITH_GO_MOD = "withGoMod";
+    public static final String USE_DEFAULT_VALUES_FOR_REQUIRED_VARS = "useDefaultValuesForRequiredVars";
     @Setter protected String goImportAlias = "openapiclient";
     protected boolean isGoSubmodule = false;
     @Setter protected boolean useOneOfDiscriminatorLookup = false; // use oneOf discriminator's mapping for model lookup
@@ -126,6 +127,7 @@ public class GoClientCodegen extends AbstractGoCodegen {
         cliOptions.add(CliOption.newBoolean(STRUCT_PREFIX, "whether to prefix struct with the class name. e.g. DeletePetOpts => PetApiDeletePetOpts"));
         cliOptions.add(CliOption.newBoolean(WITH_AWSV4_SIGNATURE, "whether to include AWS v4 signature support"));
         cliOptions.add(CliOption.newBoolean(GENERATE_INTERFACES, "Generate interfaces for api classes"));
+        cliOptions.add(CliOption.newBoolean(USE_DEFAULT_VALUES_FOR_REQUIRED_VARS, "Use default values for required variables when available"));
 
         // option to change the order of form/body parameter
         cliOptions.add(CliOption.newBoolean(
@@ -246,6 +248,11 @@ public class GoClientCodegen extends AbstractGoCodegen {
             additionalProperties.put(GENERATE_INTERFACES, generateInterfaces);
         }
 
+        if (additionalProperties.containsKey(USE_DEFAULT_VALUES_FOR_REQUIRED_VARS)) {
+            setUseDefaultValuesForRequiredVars(Boolean.parseBoolean(additionalProperties.get(USE_DEFAULT_VALUES_FOR_REQUIRED_VARS).toString()));
+            additionalProperties.put(USE_DEFAULT_VALUES_FOR_REQUIRED_VARS, useDefaultValuesForRequiredVars);
+        }
+
         // Generate the 'signing.py' module, but only if the 'HTTP signature' security scheme is specified in the OAS.
         Map<String, SecurityScheme> securitySchemeMap = openAPI != null ?
                 (openAPI.getComponents() != null ? openAPI.getComponents().getSecuritySchemes() : null) : null;

modules/openapi-generator/src/main/resources/go/model_simple.mustache

@@ -168,6 +168,18 @@ func (o *{{classname}}) Set{{name}}(v {{vendorExtensions.x-go-base-type}}) {
 {{/isNullable}}
 }
 
+{{#useDefaultValuesForRequiredVars}}
+{{^isReadOnly}}
+{{#defaultValue}}
+// GetDefault{{baseName}} function assigns the default value {{defaultValue}} to the {{name}} field
+// of the {{classname}} struct and returns the {{{defaultValue}}}.
+func (o *{{classname}}) GetDefault{{nameInPascalCase}}() interface{}  {
+	return {{{defaultValue}}}
+}
+{{/defaultValue}}
+{{/isReadOnly}}
+{{/useDefaultValuesForRequiredVars}}
+
 {{/required}}
 {{^required}}
 // Get{{name}} returns the {{name}} field value if set, zero value otherwise{{#isNullable}} (both if not set or set to explicit null){{/isNullable}}.
@@ -318,6 +330,15 @@ func (o {{classname}}) ToMap() (map[string]interface{}, error) {
 	{{! if argument is not nullable, don't set it if it is nil}}
 	{{^isNullable}}
 	{{#required}}
+	{{#useDefaultValuesForRequiredVars}}
+	{{^isReadOnly}}
+	{{#defaultValue}}
+	if _, exists := toSerialize["{{{baseName}}}"]; !exists {
+		toSerialize["{{{baseName}}}"] = o.GetDefault{{nameInPascalCase}}()
+	}
+	{{/defaultValue}}
+	{{/isReadOnly}}
+	{{/useDefaultValuesForRequiredVars}}
 	toSerialize["{{{baseName}}}"] = o.{{name}}
 	{{/required}}
 	{{^required}}
@@ -356,6 +377,20 @@ func (o *{{{classname}}}) UnmarshalJSON(data []byte) (err error) {
 {{/requiredVars}}
 	}
 
+{{#useDefaultValuesForRequiredVars}}
+	// defaultValueFuncMap captures the default values for required properties.
+	// These values are used when required properties are missing from the payload.
+	defaultValueFuncMap := map[string]func() interface{} {
+{{#requiredVars}}
+{{#defaultValue}}
+{{^isReadOnly}}
+		"{{baseName}}": o.GetDefault{{nameInPascalCase}},
+{{/isReadOnly}}
+{{/defaultValue}}
+{{/requiredVars}}
+	}
+	var defaultValueApplied bool
+{{/useDefaultValuesForRequiredVars}}
 	allProperties := make(map[string]interface{})
 
 	err = json.Unmarshal(data, &allProperties)
@@ -365,11 +400,30 @@ func (o *{{{classname}}}) UnmarshalJSON(data []byte) (err error) {
 	}
 
 	for _, requiredProperty := range(requiredProperties) {
+		{{#useDefaultValuesForRequiredVars}}
+		if value, exists := allProperties[requiredProperty]; !exists || value == "" {
+			if _, ok := defaultValueFuncMap[requiredProperty]; ok {
+				allProperties[requiredProperty] = defaultValueFuncMap[requiredProperty]()
+				defaultValueApplied = true
+			}
+		}
+		if value, exists := allProperties[requiredProperty]; !exists || value == ""{
+		{{/useDefaultValuesForRequiredVars}}
+		{{^useDefaultValuesForRequiredVars}}
 		if _, exists := allProperties[requiredProperty]; !exists {
+		{{/useDefaultValuesForRequiredVars}}
 			return fmt.Errorf("no value given for required property %v", requiredProperty)
 		}
 	}
 
+	{{#useDefaultValuesForRequiredVars}}
+	if defaultValueApplied {
+		data, err = json.Marshal(allProperties)
+		if err != nil{
+			return err
+		}
+	}
+	{{/useDefaultValuesForRequiredVars}}
 {{/hasRequired}}
 {{#isAdditionalPropertiesTrue}}
 {{#parent}}

modules/openapi-generator/src/test/java/org/openapitools/codegen/go/GoClientOptionsTest.java

@@ -54,5 +54,6 @@ public class GoClientOptionsTest extends AbstractOptionsTest {
         verify(clientCodegen).setWithGoMod(GoClientOptionsProvider.WITH_GO_MOD_VALUE);
         verify(clientCodegen).setGenerateMarshalJSON(GoClientOptionsProvider.GENERATE_MARSHAL_JSON_VALUE);
         verify(clientCodegen).setGenerateUnmarshalJSON(GoClientOptionsProvider.GENERATE_UNMARSHAL_JSON_VALUE);
+        verify(clientCodegen).setUseDefaultValuesForRequiredVars(GoClientOptionsProvider.USE_DEFAULT_VALUES_FOR_REQUIRED_VARS_VALUE);
     }
 }

modules/openapi-generator/src/test/java/org/openapitools/codegen/options/GoClientOptionsProvider.java

@@ -39,6 +39,7 @@ public class GoClientOptionsProvider implements OptionsProvider {
     public static final boolean WITH_GO_MOD_VALUE = true;
     public static final boolean GENERATE_MARSHAL_JSON_VALUE = true;
     public static final boolean GENERATE_UNMARSHAL_JSON_VALUE = true;
+    public static final boolean USE_DEFAULT_VALUES_FOR_REQUIRED_VARS_VALUE = true;
 
     @Override
     public String getLanguage() {
@@ -64,6 +65,7 @@ public class GoClientOptionsProvider implements OptionsProvider {
                 .put(CodegenConstants.GENERATE_UNMARSHAL_JSON, "true")
                 .put("generateInterfaces", "true")
                 .put("structPrefix", "true")
+                .put(CodegenConstants.USE_DEFAULT_VALUES_FOR_REQUIRED_VARS, "true")
                 .build();
     }
 

samples/client/echo_api/go-external-refs/model_pet.go

@@ -108,6 +108,7 @@ func (o *Pet) SetName(v string) {
 	o.Name = v
 }
 
+
 // GetCategory returns the Category field value if set, zero value otherwise.
 func (o *Pet) GetCategory() Category {
 	if o == nil || IsNil(o.Category) {
@@ -164,6 +165,7 @@ func (o *Pet) SetPhotoUrls(v []string) {
 	o.PhotoUrls = v
 }
 
+
 // GetTags returns the Tags field value if set, zero value otherwise.
 func (o *Pet) GetTags() []Tag {
 	if o == nil || IsNil(o.Tags) {

samples/client/echo_api/go/model_pet.go

@@ -108,6 +108,7 @@ func (o *Pet) SetName(v string) {
 	o.Name = v
 }
 
+
 // GetCategory returns the Category field value if set, zero value otherwise.
 func (o *Pet) GetCategory() Category {
 	if o == nil || IsNil(o.Category) {
@@ -164,6 +165,7 @@ func (o *Pet) SetPhotoUrls(v []string) {
 	o.PhotoUrls = v
 }
 
+
 // GetTags returns the Tags field value if set, zero value otherwise.
 func (o *Pet) GetTags() []Tag {
 	if o == nil || IsNil(o.Tags) {

samples/client/others/go/allof_multiple_ref_and_discriminator/model_additional_data.go

@@ -74,6 +74,7 @@ func (o *AdditionalData) SetProp1(v string) {
 	o.Prop1 = v
 }
 
+
 // GetQuantity returns the Quantity field value
 func (o *AdditionalData) GetQuantity() int32 {
 	if o == nil {
@@ -98,6 +99,7 @@ func (o *AdditionalData) SetQuantity(v int32) {
 	o.Quantity = v
 }
 
+
 // GetUnitPrice returns the UnitPrice field value
 func (o *AdditionalData) GetUnitPrice() float64 {
 	if o == nil {
@@ -122,6 +124,7 @@ func (o *AdditionalData) SetUnitPrice(v float64) {
 	o.UnitPrice = v
 }
 
+
 // GetTotalPrice returns the TotalPrice field value
 func (o *AdditionalData) GetTotalPrice() float64 {
 	if o == nil {
@@ -146,6 +149,7 @@ func (o *AdditionalData) SetTotalPrice(v float64) {
 	o.TotalPrice = v
 }
 
+
 func (o AdditionalData) MarshalJSON() ([]byte, error) {
 	toSerialize,err := o.ToMap()
 	if err != nil {

samples/client/others/go/allof_multiple_ref_and_discriminator/model_base_item.go

@@ -70,6 +70,7 @@ func (o *BaseItem) SetTitle(v string) {
 	o.Title = v
 }
 
+
 // GetType returns the Type field value
 func (o *BaseItem) GetType() string {
 	if o == nil {
@@ -94,6 +95,7 @@ func (o *BaseItem) SetType(v string) {
 	o.Type = v
 }
 
+
 func (o BaseItem) MarshalJSON() ([]byte, error) {
 	toSerialize,err := o.ToMap()
 	if err != nil {

samples/client/others/go/allof_multiple_ref_and_discriminator/model_final_item.go

@@ -77,6 +77,7 @@ func (o *FinalItem) SetProp1(v string) {
 	o.Prop1 = v
 }
 
+
 // GetQuantity returns the Quantity field value
 func (o *FinalItem) GetQuantity() int32 {
 	if o == nil {
@@ -101,6 +102,7 @@ func (o *FinalItem) SetQuantity(v int32) {
 	o.Quantity = v
 }
 
+
 // GetUnitPrice returns the UnitPrice field value
 func (o *FinalItem) GetUnitPrice() float64 {
 	if o == nil {
@@ -125,6 +127,7 @@ func (o *FinalItem) SetUnitPrice(v float64) {
 	o.UnitPrice = v
 }
 
+
 // GetTotalPrice returns the TotalPrice field value
 func (o *FinalItem) GetTotalPrice() float64 {
 	if o == nil {
@@ -149,6 +152,7 @@ func (o *FinalItem) SetTotalPrice(v float64) {
 	o.TotalPrice = v
 }
 
+
 func (o FinalItem) MarshalJSON() ([]byte, error) {
 	toSerialize,err := o.ToMap()
 	if err != nil {

samples/client/others/go/oneof-anyof-required/model_nested_object1.go

@@ -69,6 +69,7 @@ func (o *NestedObject1) SetField1(v string) {
 	o.Field1 = v
 }
 
+
 func (o NestedObject1) MarshalJSON() ([]byte, error) {
 	toSerialize,err := o.ToMap()
 	if err != nil {

samples/client/others/go/oneof-anyof-required/model_nested_object2.go

@@ -69,6 +69,7 @@ func (o *NestedObject2) SetField2(v string) {
 	o.Field2 = v
 }
 
+
 func (o NestedObject2) MarshalJSON() ([]byte, error) {
 	toSerialize,err := o.ToMap()
 	if err != nil {

samples/client/petstore/go/go-petstore/model_animal.go

@@ -73,6 +73,7 @@ func (o *Animal) SetClassName(v string) {
 	o.ClassName = v
 }
 
+
 // GetColor returns the Color field value if set, zero value otherwise.
 func (o *Animal) GetColor() string {
 	if o == nil || IsNil(o.Color) {

samples/client/petstore/go/go-petstore/model_category.go

@@ -103,6 +103,7 @@ func (o *Category) SetName(v string) {
 	o.Name = v
 }
 
+
 func (o Category) MarshalJSON() ([]byte, error) {
 	toSerialize,err := o.ToMap()
 	if err != nil {

samples/client/petstore/go/go-petstore/model_enum_test_.go

@@ -104,6 +104,7 @@ func (o *EnumTest) SetEnumStringRequired(v string) {
 	o.EnumStringRequired = v
 }
 
+
 // GetEnumInteger returns the EnumInteger field value if set, zero value otherwise.
 func (o *EnumTest) GetEnumInteger() int32 {
 	if o == nil || IsNil(o.EnumInteger) {

samples/client/petstore/go/go-petstore/model_format_test_.go

@@ -182,6 +182,7 @@ func (o *FormatTest) SetNumber(v float32) {
 	o.Number = v
 }
 
+
 // GetFloat returns the Float field value if set, zero value otherwise.
 func (o *FormatTest) GetFloat() float32 {
 	if o == nil || IsNil(o.Float) {
@@ -302,6 +303,7 @@ func (o *FormatTest) SetByte(v string) {
 	o.Byte = v
 }
 
+
 // GetBinary returns the Binary field value if set, zero value otherwise.
 func (o *FormatTest) GetBinary() *os.File {
 	if o == nil || IsNil(o.Binary) {
@@ -358,6 +360,7 @@ func (o *FormatTest) SetDate(v string) {
 	o.Date = v
 }
 
+
 // GetDateTime returns the DateTime field value if set, zero value otherwise.
 func (o *FormatTest) GetDateTime() time.Time {
 	if o == nil || IsNil(o.DateTime) {
@@ -446,6 +449,7 @@ func (o *FormatTest) SetPassword(v string) {
 	o.Password = v
 }
 
+
 // GetBigDecimal returns the BigDecimal field value if set, zero value otherwise.
 func (o *FormatTest) GetBigDecimal() float64 {
 	if o == nil || IsNil(o.BigDecimal) {

samples/client/petstore/go/go-petstore/model_name.go

@@ -71,6 +71,7 @@ func (o *Name) SetName(v int32) {
 	o.Name = v
 }
 
+
 // GetSnakeCase returns the SnakeCase field value if set, zero value otherwise.
 func (o *Name) GetSnakeCase() int32 {
 	if o == nil || IsNil(o.SnakeCase) {

samples/client/petstore/go/go-petstore/model_pet.go

@@ -139,6 +139,7 @@ func (o *Pet) SetName(v string) {
 	o.Name = v
 }
 
+
 // GetPhotoUrls returns the PhotoUrls field value
 func (o *Pet) GetPhotoUrls() []string {
 	if o == nil {
@@ -163,6 +164,7 @@ func (o *Pet) SetPhotoUrls(v []string) {
 	o.PhotoUrls = v
 }
 
+
 // GetTags returns the Tags field value if set, zero value otherwise.
 func (o *Pet) GetTags() []Tag {
 	if o == nil || IsNil(o.Tags) {

samples/client/petstore/go/go-petstore/model_type_holder_default.go

@@ -80,6 +80,7 @@ func (o *TypeHolderDefault) SetStringItem(v string) {
 	o.StringItem = v
 }
 
+
 // GetNumberItem returns the NumberItem field value
 func (o *TypeHolderDefault) GetNumberItem() float32 {
 	if o == nil {
@@ -104,6 +105,7 @@ func (o *TypeHolderDefault) SetNumberItem(v float32) {
 	o.NumberItem = v
 }
 
+
 // GetIntegerItem returns the IntegerItem field value
 func (o *TypeHolderDefault) GetIntegerItem() int32 {
 	if o == nil {
@@ -128,6 +130,7 @@ func (o *TypeHolderDefault) SetIntegerItem(v int32) {
 	o.IntegerItem = v
 }
 
+
 // GetBoolItem returns the BoolItem field value
 func (o *TypeHolderDefault) GetBoolItem() bool {
 	if o == nil {
@@ -152,6 +155,7 @@ func (o *TypeHolderDefault) SetBoolItem(v bool) {
 	o.BoolItem = v
 }
 
+
 // GetArrayItem returns the ArrayItem field value
 func (o *TypeHolderDefault) GetArrayItem() []int32 {
 	if o == nil {
@@ -176,6 +180,7 @@ func (o *TypeHolderDefault) SetArrayItem(v []int32) {
 	o.ArrayItem = v
 }
 
+
 func (o TypeHolderDefault) MarshalJSON() ([]byte, error) {
 	toSerialize,err := o.ToMap()
 	if err != nil {

samples/client/petstore/go/go-petstore/model_type_holder_example.go

@@ -78,6 +78,7 @@ func (o *TypeHolderExample) SetStringItem(v string) {
 	o.StringItem = v
 }
 
+
 // GetNumberItem returns the NumberItem field value
 func (o *TypeHolderExample) GetNumberItem() float32 {
 	if o == nil {
@@ -102,6 +103,7 @@ func (o *TypeHolderExample) SetNumberItem(v float32) {
 	o.NumberItem = v
 }
 
+
 // GetFloatItem returns the FloatItem field value
 func (o *TypeHolderExample) GetFloatItem() float32 {
 	if o == nil {
@@ -126,6 +128,7 @@ func (o *TypeHolderExample) SetFloatItem(v float32) {
 	o.FloatItem = v
 }
 
+
 // GetIntegerItem returns the IntegerItem field value
 func (o *TypeHolderExample) GetIntegerItem() int32 {
 	if o == nil {
@@ -150,6 +153,7 @@ func (o *TypeHolderExample) SetIntegerItem(v int32) {
 	o.IntegerItem = v
 }
 
+
 // GetBoolItem returns the BoolItem field value
 func (o *TypeHolderExample) GetBoolItem() bool {
 	if o == nil {
@@ -174,6 +178,7 @@ func (o *TypeHolderExample) SetBoolItem(v bool) {
 	o.BoolItem = v
 }
 
+
 // GetArrayItem returns the ArrayItem field value
 func (o *TypeHolderExample) GetArrayItem() []int32 {
 	if o == nil {
@@ -198,6 +203,7 @@ func (o *TypeHolderExample) SetArrayItem(v []int32) {
 	o.ArrayItem = v
 }
 
+
 func (o TypeHolderExample) MarshalJSON() ([]byte, error) {
 	toSerialize,err := o.ToMap()
 	if err != nil {

samples/openapi3/client/petstore/go-petstore-generateMarshalJSON-false/model_pet.go

@@ -140,6 +140,7 @@ func (o *Pet) SetName(v string) {
 	o.Name = v
 }
 
+
 // GetPhotoUrls returns the PhotoUrls field value
 func (o *Pet) GetPhotoUrls() []string {
 	if o == nil {
@@ -164,6 +165,7 @@ func (o *Pet) SetPhotoUrls(v []string) {
 	o.PhotoUrls = v
 }
 
+
 // GetTags returns the Tags field value if set, zero value otherwise.
 func (o *Pet) GetTags() []Tag {
 	if o == nil || IsNil(o.Tags) {

samples/openapi3/client/petstore/go/go-petstore/model_animal.go

@@ -73,6 +73,7 @@ func (o *Animal) SetClassName(v string) {
 	o.ClassName = v
 }
 
+
 // GetColor returns the Color field value if set, zero value otherwise.
 func (o *Animal) GetColor() string {
 	if o == nil || IsNil(o.Color) {
@@ -135,6 +136,11 @@ func (o *Animal) UnmarshalJSON(data []byte) (err error) {
 		"className",
 	}
 
+	// defaultValueFuncMap captures the default values for required properties.
+	// These values are used when required properties are missing from the payload.
+	defaultValueFuncMap := map[string]func() interface{} {
+	}
+	var defaultValueApplied bool
 	allProperties := make(map[string]interface{})
 
 	err = json.Unmarshal(data, &allProperties)
@@ -144,11 +150,23 @@ func (o *Animal) UnmarshalJSON(data []byte) (err error) {
 	}
 
 	for _, requiredProperty := range(requiredProperties) {
-		if _, exists := allProperties[requiredProperty]; !exists {
+		if value, exists := allProperties[requiredProperty]; !exists || value == "" {
+			if _, ok := defaultValueFuncMap[requiredProperty]; ok {
+				allProperties[requiredProperty] = defaultValueFuncMap[requiredProperty]()
+				defaultValueApplied = true
+			}
+		}
+		if value, exists := allProperties[requiredProperty]; !exists || value == ""{
 			return fmt.Errorf("no value given for required property %v", requiredProperty)
 		}
 	}
 
+	if defaultValueApplied {
+		data, err = json.Marshal(allProperties)
+		if err != nil{
+			return err
+		}
+	}
 	varAnimal := _Animal{}
 
 	err = json.Unmarshal(data, &varAnimal)

samples/openapi3/client/petstore/go/go-petstore/model_apple_req.go

@@ -69,6 +69,7 @@ func (o *AppleReq) SetCultivar(v string) {
 	o.Cultivar = v
 }
 
+
 // GetMealy returns the Mealy field value if set, zero value otherwise.
 func (o *AppleReq) GetMealy() bool {
 	if o == nil || IsNil(o.Mealy) {
@@ -131,6 +132,11 @@ func (o *AppleReq) UnmarshalJSON(data []byte) (err error) {
 		"cultivar",
 	}
 
+	// defaultValueFuncMap captures the default values for required properties.
+	// These values are used when required properties are missing from the payload.
+	defaultValueFuncMap := map[string]func() interface{} {
+	}
+	var defaultValueApplied bool
 	allProperties := make(map[string]interface{})
 
 	err = json.Unmarshal(data, &allProperties)
@@ -140,11 +146,23 @@ func (o *AppleReq) UnmarshalJSON(data []byte) (err error) {
 	}
 
 	for _, requiredProperty := range(requiredProperties) {
-		if _, exists := allProperties[requiredProperty]; !exists {
+		if value, exists := allProperties[requiredProperty]; !exists || value == "" {
+			if _, ok := defaultValueFuncMap[requiredProperty]; ok {
+				allProperties[requiredProperty] = defaultValueFuncMap[requiredProperty]()
+				defaultValueApplied = true
+			}
+		}
+		if value, exists := allProperties[requiredProperty]; !exists || value == ""{
 			return fmt.Errorf("no value given for required property %v", requiredProperty)
 		}
 	}
 
+	if defaultValueApplied {
+		data, err = json.Marshal(allProperties)
+		if err != nil{
+			return err
+		}
+	}
 	varAppleReq := _AppleReq{}
 
 	err = json.Unmarshal(data, &varAppleReq)

samples/openapi3/client/petstore/go/go-petstore/model_banana_req.go

@@ -69,6 +69,7 @@ func (o *BananaReq) SetLengthCm(v float32) {
 	o.LengthCm = v
 }
 
+
 // GetSweet returns the Sweet field value if set, zero value otherwise.
 func (o *BananaReq) GetSweet() bool {
 	if o == nil || IsNil(o.Sweet) {
@@ -131,6 +132,11 @@ func (o *BananaReq) UnmarshalJSON(data []byte) (err error) {
 		"lengthCm",
 	}
 
+	// defaultValueFuncMap captures the default values for required properties.
+	// These values are used when required properties are missing from the payload.
+	defaultValueFuncMap := map[string]func() interface{} {
+	}
+	var defaultValueApplied bool
 	allProperties := make(map[string]interface{})
 
 	err = json.Unmarshal(data, &allProperties)
@@ -140,11 +146,23 @@ func (o *BananaReq) UnmarshalJSON(data []byte) (err error) {
 	}
 
 	for _, requiredProperty := range(requiredProperties) {
-		if _, exists := allProperties[requiredProperty]; !exists {
+		if value, exists := allProperties[requiredProperty]; !exists || value == "" {
+			if _, ok := defaultValueFuncMap[requiredProperty]; ok {
+				allProperties[requiredProperty] = defaultValueFuncMap[requiredProperty]()
+				defaultValueApplied = true
+			}
+		}
+		if value, exists := allProperties[requiredProperty]; !exists || value == ""{
 			return fmt.Errorf("no value given for required property %v", requiredProperty)
 		}
 	}
 
+	if defaultValueApplied {
+		data, err = json.Marshal(allProperties)
+		if err != nil{
+			return err
+		}
+	}
 	varBananaReq := _BananaReq{}
 
 	err = json.Unmarshal(data, &varBananaReq)

samples/openapi3/client/petstore/go/go-petstore/model_cat.go

@@ -118,6 +118,11 @@ func (o *Cat) UnmarshalJSON(data []byte) (err error) {
 		"className",
 	}
 
+	// defaultValueFuncMap captures the default values for required properties.
+	// These values are used when required properties are missing from the payload.
+	defaultValueFuncMap := map[string]func() interface{} {
+	}
+	var defaultValueApplied bool
 	allProperties := make(map[string]interface{})
 
 	err = json.Unmarshal(data, &allProperties)
@@ -127,11 +132,23 @@ func (o *Cat) UnmarshalJSON(data []byte) (err error) {
 	}
 
 	for _, requiredProperty := range(requiredProperties) {
-		if _, exists := allProperties[requiredProperty]; !exists {
+		if value, exists := allProperties[requiredProperty]; !exists || value == "" {
+			if _, ok := defaultValueFuncMap[requiredProperty]; ok {
+				allProperties[requiredProperty] = defaultValueFuncMap[requiredProperty]()
+				defaultValueApplied = true
+			}
+		}
+		if value, exists := allProperties[requiredProperty]; !exists || value == ""{
 			return fmt.Errorf("no value given for required property %v", requiredProperty)
 		}
 	}
 
+	if defaultValueApplied {
+		data, err = json.Marshal(allProperties)
+		if err != nil{
+			return err
+		}
+	}
 	type CatWithoutEmbeddedStruct struct {
 		Declawed *bool `json:"declawed,omitempty"`
 	}

samples/openapi3/client/petstore/go/go-petstore/model_category.go

@@ -103,6 +103,12 @@ func (o *Category) SetName(v string) {
 	o.Name = v
 }
 
+// GetDefaultname function assigns the default value "default-name" to the Name field
+// of the Category struct and returns the "default-name".
+func (o *Category) GetDefaultName() interface{}  {
+	return "default-name"
+}
+
 func (o Category) MarshalJSON() ([]byte, error) {
 	toSerialize,err := o.ToMap()
 	if err != nil {
@@ -116,6 +122,9 @@ func (o Category) ToMap() (map[string]interface{}, error) {
 	if !IsNil(o.Id) {
 		toSerialize["id"] = o.Id
 	}
+	if _, exists := toSerialize["name"]; !exists {
+		toSerialize["name"] = o.GetDefaultName()
+	}
 	toSerialize["name"] = o.Name
 
 	for key, value := range o.AdditionalProperties {
@@ -133,6 +142,12 @@ func (o *Category) UnmarshalJSON(data []byte) (err error) {
 		"name",
 	}
 
+	// defaultValueFuncMap captures the default values for required properties.
+	// These values are used when required properties are missing from the payload.
+	defaultValueFuncMap := map[string]func() interface{} {
+		"name": o.GetDefaultName,
+	}
+	var defaultValueApplied bool
 	allProperties := make(map[string]interface{})
 
 	err = json.Unmarshal(data, &allProperties)
@@ -142,11 +157,23 @@ func (o *Category) UnmarshalJSON(data []byte) (err error) {
 	}
 
 	for _, requiredProperty := range(requiredProperties) {
-		if _, exists := allProperties[requiredProperty]; !exists {
+		if value, exists := allProperties[requiredProperty]; !exists || value == "" {
+			if _, ok := defaultValueFuncMap[requiredProperty]; ok {
+				allProperties[requiredProperty] = defaultValueFuncMap[requiredProperty]()
+				defaultValueApplied = true
+			}
+		}
+		if value, exists := allProperties[requiredProperty]; !exists || value == ""{
 			return fmt.Errorf("no value given for required property %v", requiredProperty)
 		}
 	}
 
+	if defaultValueApplied {
+		data, err = json.Marshal(allProperties)
+		if err != nil{
+			return err
+		}
+	}
 	varCategory := _Category{}
 
 	err = json.Unmarshal(data, &varCategory)

samples/openapi3/client/petstore/go/go-petstore/model_dog.go

@@ -118,6 +118,11 @@ func (o *Dog) UnmarshalJSON(data []byte) (err error) {
 		"className",
 	}
 
+	// defaultValueFuncMap captures the default values for required properties.
+	// These values are used when required properties are missing from the payload.
+	defaultValueFuncMap := map[string]func() interface{} {
+	}
+	var defaultValueApplied bool
 	allProperties := make(map[string]interface{})
 
 	err = json.Unmarshal(data, &allProperties)
@@ -127,11 +132,23 @@ func (o *Dog) UnmarshalJSON(data []byte) (err error) {
 	}
 
 	for _, requiredProperty := range(requiredProperties) {
-		if _, exists := allProperties[requiredProperty]; !exists {
+		if value, exists := allProperties[requiredProperty]; !exists || value == "" {
+			if _, ok := defaultValueFuncMap[requiredProperty]; ok {
+				allProperties[requiredProperty] = defaultValueFuncMap[requiredProperty]()
+				defaultValueApplied = true
+			}
+		}
+		if value, exists := allProperties[requiredProperty]; !exists || value == ""{
 			return fmt.Errorf("no value given for required property %v", requiredProperty)
 		}
 	}
 
+	if defaultValueApplied {
+		data, err = json.Marshal(allProperties)
+		if err != nil{
+			return err
+		}
+	}
 	type DogWithoutEmbeddedStruct struct {
 		Breed *string `json:"breed,omitempty"`
 	}

samples/openapi3/client/petstore/go/go-petstore/model_duplicated_prop_parent.go

@@ -69,6 +69,7 @@ func (o *DuplicatedPropParent) SetDupProp(v string) {
 	o.DupProp = v
 }
 
+
 func (o DuplicatedPropParent) MarshalJSON() ([]byte, error) {
 	toSerialize,err := o.ToMap()
 	if err != nil {
@@ -96,6 +97,11 @@ func (o *DuplicatedPropParent) UnmarshalJSON(data []byte) (err error) {
 		"dup-prop",
 	}
 
+	// defaultValueFuncMap captures the default values for required properties.
+	// These values are used when required properties are missing from the payload.
+	defaultValueFuncMap := map[string]func() interface{} {
+	}
+	var defaultValueApplied bool
 	allProperties := make(map[string]interface{})
 
 	err = json.Unmarshal(data, &allProperties)
@@ -105,11 +111,23 @@ func (o *DuplicatedPropParent) UnmarshalJSON(data []byte) (err error) {
 	}
 
 	for _, requiredProperty := range(requiredProperties) {
-		if _, exists := allProperties[requiredProperty]; !exists {
+		if value, exists := allProperties[requiredProperty]; !exists || value == "" {
+			if _, ok := defaultValueFuncMap[requiredProperty]; ok {
+				allProperties[requiredProperty] = defaultValueFuncMap[requiredProperty]()
+				defaultValueApplied = true
+			}
+		}
+		if value, exists := allProperties[requiredProperty]; !exists || value == ""{
 			return fmt.Errorf("no value given for required property %v", requiredProperty)
 		}
 	}
 
+	if defaultValueApplied {
+		data, err = json.Marshal(allProperties)
+		if err != nil{
+			return err
+		}
+	}
 	varDuplicatedPropParent := _DuplicatedPropParent{}
 
 	err = json.Unmarshal(data, &varDuplicatedPropParent)

samples/openapi3/client/petstore/go/go-petstore/model_enum_test_.go

@@ -115,6 +115,7 @@ func (o *EnumTest) SetEnumStringRequired(v string) {
 	o.EnumStringRequired = v
 }
 
+
 // GetEnumInteger returns the EnumInteger field value if set, zero value otherwise.
 func (o *EnumTest) GetEnumInteger() int32 {
 	if o == nil || IsNil(o.EnumInteger) {
@@ -365,6 +366,11 @@ func (o *EnumTest) UnmarshalJSON(data []byte) (err error) {
 		"enum_string_required",
 	}
 
+	// defaultValueFuncMap captures the default values for required properties.
+	// These values are used when required properties are missing from the payload.
+	defaultValueFuncMap := map[string]func() interface{} {
+	}
+	var defaultValueApplied bool
 	allProperties := make(map[string]interface{})
 
 	err = json.Unmarshal(data, &allProperties)
@@ -374,11 +380,23 @@ func (o *EnumTest) UnmarshalJSON(data []byte) (err error) {
 	}
 
 	for _, requiredProperty := range(requiredProperties) {
-		if _, exists := allProperties[requiredProperty]; !exists {
+		if value, exists := allProperties[requiredProperty]; !exists || value == "" {
+			if _, ok := defaultValueFuncMap[requiredProperty]; ok {
+				allProperties[requiredProperty] = defaultValueFuncMap[requiredProperty]()
+				defaultValueApplied = true
+			}
+		}
+		if value, exists := allProperties[requiredProperty]; !exists || value == ""{
 			return fmt.Errorf("no value given for required property %v", requiredProperty)
 		}
 	}
 
+	if defaultValueApplied {
+		data, err = json.Marshal(allProperties)
+		if err != nil{
+			return err
+		}
+	}
 	varEnumTest := _EnumTest{}
 
 	err = json.Unmarshal(data, &varEnumTest)

samples/openapi3/client/petstore/go/go-petstore/model_foo.go

@@ -72,6 +72,12 @@ func (o *Foo) SetBar(v string) {
 	o.Bar = v
 }
 
+// GetDefaultbar function assigns the default value "bar" to the Bar field
+// of the Foo struct and returns the "bar".
+func (o *Foo) GetDefaultBar() interface{}  {
+	return "bar"
+}
+
 // GetMap returns the Map field value if set, zero value otherwise.
 func (o *Foo) GetMap() map[string][]time.Time {
 	if o == nil || IsNil(o.Map) {
@@ -114,6 +120,9 @@ func (o Foo) MarshalJSON() ([]byte, error) {
 
 func (o Foo) ToMap() (map[string]interface{}, error) {
 	toSerialize := map[string]interface{}{}
+	if _, exists := toSerialize["bar"]; !exists {
+		toSerialize["bar"] = o.GetDefaultBar()
+	}
 	toSerialize["bar"] = o.Bar
 	if !IsNil(o.Map) {
 		toSerialize["map"] = o.Map
@@ -134,6 +143,12 @@ func (o *Foo) UnmarshalJSON(data []byte) (err error) {
 		"bar",
 	}
 
+	// defaultValueFuncMap captures the default values for required properties.
+	// These values are used when required properties are missing from the payload.
+	defaultValueFuncMap := map[string]func() interface{} {
+		"bar": o.GetDefaultBar,
+	}
+	var defaultValueApplied bool
 	allProperties := make(map[string]interface{})
 
 	err = json.Unmarshal(data, &allProperties)
@@ -143,11 +158,23 @@ func (o *Foo) UnmarshalJSON(data []byte) (err error) {
 	}
 
 	for _, requiredProperty := range(requiredProperties) {
-		if _, exists := allProperties[requiredProperty]; !exists {
+		if value, exists := allProperties[requiredProperty]; !exists || value == "" {
+			if _, ok := defaultValueFuncMap[requiredProperty]; ok {
+				allProperties[requiredProperty] = defaultValueFuncMap[requiredProperty]()
+				defaultValueApplied = true
+			}
+		}
+		if value, exists := allProperties[requiredProperty]; !exists || value == ""{
 			return fmt.Errorf("no value given for required property %v", requiredProperty)
 		}
 	}
 
+	if defaultValueApplied {
+		data, err = json.Marshal(allProperties)
+		if err != nil{
+			return err
+		}
+	}
 	varFoo := _Foo{}
 
 	err = json.Unmarshal(data, &varFoo)

samples/openapi3/client/petstore/go/go-petstore/model_format_test_.go

@@ -185,6 +185,7 @@ func (o *FormatTest) SetNumber(v float32) {
 	o.Number = v
 }
 
+
 // GetFloat returns the Float field value if set, zero value otherwise.
 func (o *FormatTest) GetFloat() float32 {
 	if o == nil || IsNil(o.Float) {
@@ -305,6 +306,7 @@ func (o *FormatTest) SetByte(v string) {
 	o.Byte = v
 }
 
+
 // GetBinary returns the Binary field value if set, zero value otherwise.
 func (o *FormatTest) GetBinary() *os.File {
 	if o == nil || IsNil(o.Binary) {
@@ -361,6 +363,7 @@ func (o *FormatTest) SetDate(v string) {
 	o.Date = v
 }
 
+
 // GetDateTime returns the DateTime field value if set, zero value otherwise.
 func (o *FormatTest) GetDateTime() time.Time {
 	if o == nil || IsNil(o.DateTime) {
@@ -449,6 +452,7 @@ func (o *FormatTest) SetPassword(v string) {
 	o.Password = v
 }
 
+
 // GetPatternWithDigits returns the PatternWithDigits field value if set, zero value otherwise.
 func (o *FormatTest) GetPatternWithDigits() string {
 	if o == nil || IsNil(o.PatternWithDigits) {
@@ -579,6 +583,11 @@ func (o *FormatTest) UnmarshalJSON(data []byte) (err error) {
 		"password",
 	}
 
+	// defaultValueFuncMap captures the default values for required properties.
+	// These values are used when required properties are missing from the payload.
+	defaultValueFuncMap := map[string]func() interface{} {
+	}
+	var defaultValueApplied bool
 	allProperties := make(map[string]interface{})
 
 	err = json.Unmarshal(data, &allProperties)
@@ -588,11 +597,23 @@ func (o *FormatTest) UnmarshalJSON(data []byte) (err error) {
 	}
 
 	for _, requiredProperty := range(requiredProperties) {
-		if _, exists := allProperties[requiredProperty]; !exists {
+		if value, exists := allProperties[requiredProperty]; !exists || value == "" {
+			if _, ok := defaultValueFuncMap[requiredProperty]; ok {
+				allProperties[requiredProperty] = defaultValueFuncMap[requiredProperty]()
+				defaultValueApplied = true
+			}
+		}
+		if value, exists := allProperties[requiredProperty]; !exists || value == ""{
 			return fmt.Errorf("no value given for required property %v", requiredProperty)
 		}
 	}
 
+	if defaultValueApplied {
+		data, err = json.Marshal(allProperties)
+		if err != nil{
+			return err
+		}
+	}
 	varFormatTest := _FormatTest{}
 
 	err = json.Unmarshal(data, &varFormatTest)

samples/openapi3/client/petstore/go/go-petstore/model_name.go

@@ -71,6 +71,7 @@ func (o *Name) SetName(v int32) {
 	o.Name = v
 }
 
+
 // GetSnakeCase returns the SnakeCase field value if set, zero value otherwise.
 func (o *Name) GetSnakeCase() int32 {
 	if o == nil || IsNil(o.SnakeCase) {
@@ -203,6 +204,11 @@ func (o *Name) UnmarshalJSON(data []byte) (err error) {
 		"name",
 	}
 
+	// defaultValueFuncMap captures the default values for required properties.
+	// These values are used when required properties are missing from the payload.
+	defaultValueFuncMap := map[string]func() interface{} {
+	}
+	var defaultValueApplied bool
 	allProperties := make(map[string]interface{})
 
 	err = json.Unmarshal(data, &allProperties)
@@ -212,11 +218,23 @@ func (o *Name) UnmarshalJSON(data []byte) (err error) {
 	}
 
 	for _, requiredProperty := range(requiredProperties) {
-		if _, exists := allProperties[requiredProperty]; !exists {
+		if value, exists := allProperties[requiredProperty]; !exists || value == "" {
+			if _, ok := defaultValueFuncMap[requiredProperty]; ok {
+				allProperties[requiredProperty] = defaultValueFuncMap[requiredProperty]()
+				defaultValueApplied = true
+			}
+		}
+		if value, exists := allProperties[requiredProperty]; !exists || value == ""{
 			return fmt.Errorf("no value given for required property %v", requiredProperty)
 		}
 	}
 
+	if defaultValueApplied {
+		data, err = json.Marshal(allProperties)
+		if err != nil{
+			return err
+		}
+	}
 	varName := _Name{}
 
 	err = json.Unmarshal(data, &varName)

samples/openapi3/client/petstore/go/go-petstore/model_pet.go

@@ -140,6 +140,7 @@ func (o *Pet) SetName(v string) {
 	o.Name = v
 }
 
+
 // GetPhotoUrls returns the PhotoUrls field value
 func (o *Pet) GetPhotoUrls() []string {
 	if o == nil {
@@ -164,6 +165,7 @@ func (o *Pet) SetPhotoUrls(v []string) {
 	o.PhotoUrls = v
 }
 
+
 // GetTags returns the Tags field value if set, zero value otherwise.
 func (o *Pet) GetTags() []Tag {
 	if o == nil || IsNil(o.Tags) {
@@ -272,6 +274,11 @@ func (o *Pet) UnmarshalJSON(data []byte) (err error) {
 		"photoUrls",
 	}
 
+	// defaultValueFuncMap captures the default values for required properties.
+	// These values are used when required properties are missing from the payload.
+	defaultValueFuncMap := map[string]func() interface{} {
+	}
+	var defaultValueApplied bool
 	allProperties := make(map[string]interface{})
 
 	err = json.Unmarshal(data, &allProperties)
@@ -281,11 +288,23 @@ func (o *Pet) UnmarshalJSON(data []byte) (err error) {
 	}
 
 	for _, requiredProperty := range(requiredProperties) {
-		if _, exists := allProperties[requiredProperty]; !exists {
+		if value, exists := allProperties[requiredProperty]; !exists || value == "" {
+			if _, ok := defaultValueFuncMap[requiredProperty]; ok {
+				allProperties[requiredProperty] = defaultValueFuncMap[requiredProperty]()
+				defaultValueApplied = true
+			}
+		}
+		if value, exists := allProperties[requiredProperty]; !exists || value == ""{
 			return fmt.Errorf("no value given for required property %v", requiredProperty)
 		}
 	}
 
+	if defaultValueApplied {
+		data, err = json.Marshal(allProperties)
+		if err != nil{
+			return err
+		}
+	}
 	varPet := _Pet{}
 
 	err = json.Unmarshal(data, &varPet)

samples/openapi3/client/petstore/go/go-petstore/model_whale.go

@@ -134,6 +134,7 @@ func (o *Whale) SetClassName(v string) {
 	o.ClassName = v
 }
 
+
 func (o Whale) MarshalJSON() ([]byte, error) {
 	toSerialize,err := o.ToMap()
 	if err != nil {
@@ -167,6 +168,11 @@ func (o *Whale) UnmarshalJSON(data []byte) (err error) {
 		"className",
 	}
 
+	// defaultValueFuncMap captures the default values for required properties.
+	// These values are used when required properties are missing from the payload.
+	defaultValueFuncMap := map[string]func() interface{} {
+	}
+	var defaultValueApplied bool
 	allProperties := make(map[string]interface{})
 
 	err = json.Unmarshal(data, &allProperties)
@@ -176,11 +182,23 @@ func (o *Whale) UnmarshalJSON(data []byte) (err error) {
 	}
 
 	for _, requiredProperty := range(requiredProperties) {
-		if _, exists := allProperties[requiredProperty]; !exists {
+		if value, exists := allProperties[requiredProperty]; !exists || value == "" {
+			if _, ok := defaultValueFuncMap[requiredProperty]; ok {
+				allProperties[requiredProperty] = defaultValueFuncMap[requiredProperty]()
+				defaultValueApplied = true
+			}
+		}
+		if value, exists := allProperties[requiredProperty]; !exists || value == ""{
 			return fmt.Errorf("no value given for required property %v", requiredProperty)
 		}
 	}
 
+	if defaultValueApplied {
+		data, err = json.Marshal(allProperties)
+		if err != nil{
+			return err
+		}
+	}
 	varWhale := _Whale{}
 
 	err = json.Unmarshal(data, &varWhale)

samples/openapi3/client/petstore/go/go-petstore/model_zebra.go

@@ -101,6 +101,7 @@ func (o *Zebra) SetClassName(v string) {
 	o.ClassName = v
 }
 
+
 func (o Zebra) MarshalJSON() ([]byte, error) {
 	toSerialize,err := o.ToMap()
 	if err != nil {
@@ -131,6 +132,11 @@ func (o *Zebra) UnmarshalJSON(data []byte) (err error) {
 		"className",
 	}
 
+	// defaultValueFuncMap captures the default values for required properties.
+	// These values are used when required properties are missing from the payload.
+	defaultValueFuncMap := map[string]func() interface{} {
+	}
+	var defaultValueApplied bool
 	allProperties := make(map[string]interface{})
 
 	err = json.Unmarshal(data, &allProperties)
@@ -140,11 +146,23 @@ func (o *Zebra) UnmarshalJSON(data []byte) (err error) {
 	}
 
 	for _, requiredProperty := range(requiredProperties) {
-		if _, exists := allProperties[requiredProperty]; !exists {
+		if value, exists := allProperties[requiredProperty]; !exists || value == "" {
+			if _, ok := defaultValueFuncMap[requiredProperty]; ok {
+				allProperties[requiredProperty] = defaultValueFuncMap[requiredProperty]()
+				defaultValueApplied = true
+			}
+		}
+		if value, exists := allProperties[requiredProperty]; !exists || value == ""{
 			return fmt.Errorf("no value given for required property %v", requiredProperty)
 		}
 	}
 
+	if defaultValueApplied {
+		data, err = json.Marshal(allProperties)
+		if err != nil{
+			return err
+		}
+	}
 	varZebra := _Zebra{}
 
 	err = json.Unmarshal(data, &varZebra)