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

Author: vvb

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

@@ -449,4 +449,6 @@ public static enum ENUM_PROPERTY_NAMING_TYPE {camelCase, PascalCase, snake_case,
     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

@@ -40,15 +40,26 @@ public abstract class AbstractGoCodegen extends DefaultCodegen implements Codege
     private final Logger LOGGER = LoggerFactory.getLogger(AbstractGoCodegen.class);
     private static final String NUMERIC_ENUM_PREFIX = "_";
 
-    @Setter protected boolean withGoCodegenComment = false;
-    @Setter protected boolean withAWSV4Signature = false;
-    @Setter protected boolean withXml = false;
-    @Setter protected boolean enumClassPrefix = false;
-    @Setter protected boolean structPrefix = false;
-    @Setter protected boolean generateInterfaces = false;
-    @Setter protected boolean withGoMod = false;
-    @Setter protected boolean generateMarshalJSON = true;
-    @Setter protected boolean generateUnmarshalJSON = true;
+    @Setter
+    protected boolean withGoCodegenComment = false;
+    @Setter
+    protected boolean withAWSV4Signature = false;
+    @Setter
+    protected boolean withXml = false;
+    @Setter
+    protected boolean enumClassPrefix = false;
+    @Setter
+    protected boolean structPrefix = false;
+    @Setter
+    protected boolean generateInterfaces = false;
+    @Setter
+    protected boolean withGoMod = false;
+    @Setter
+    protected boolean generateMarshalJSON = true;
+    @Setter
+    protected boolean generateUnmarshalJSON = true;
+    @Setter
+    protected boolean useDefaultValuesForRequiredVars = false;
 
     @Setter protected String packageName = "openapi";
     protected Set<String> numberTypes;

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 GoClientCodegen() {
         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 void processOpts() {
             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 @@ protected void verifyOptions() {
         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 Map<String, String> createOptions() {
                 .put(CodegenConstants.GENERATE_UNMARSHAL_JSON, "true")
                 .put("generateInterfaces", "true")
                 .put("structPrefix", "true")
+                .put(CodegenConstants.USE_DEFAULT_VALUES_FOR_REQUIRED_VARS, "true")
                 .build();
     }