Add x-go-name property extension (#517)

README.md

@@ -474,6 +474,10 @@ which help you to use the various OpenAPI 3 Authentication mechanism.
   will override any default value. This extended property isn't supported in all parts of
   OpenAPI, so please refer to the spec as to where it's allowed. Swagger validation tools will
   flag incorrect usage of this property.
+- `x-go-name`: specifies Go field name. It allows you to specify the field name for a schema, and
+  will override any default value. This extended property isn't supported in all parts of
+  OpenAPI, so please refer to the spec as to where it's allowed. Swagger validation tools will
+  flag incorrect usage of this property.
 - `x-oapi-codegen-extra-tags`: adds extra Go field tags to the generated struct field. This is
   useful for interfacing with tag based ORM or validation libraries. The extra tags that
   are added are in addition to the regular json tags that are generated. If you specify your 

pkg/codegen/extension.go

@@ -7,21 +7,29 @@ import (
 
 const (
 	extPropGoType    = "x-go-type"
+	extGoFieldName   = "x-go-name"
 	extPropOmitEmpty = "x-omitempty"
 	extPropExtraTags = "x-oapi-codegen-extra-tags"
 )
 
-func extTypeName(extPropValue interface{}) (string, error) {
+func extString(extPropValue interface{}) (string, error) {
 	raw, ok := extPropValue.(json.RawMessage)
 	if !ok {
 		return "", fmt.Errorf("failed to convert type: %T", extPropValue)
 	}
-	var name string
-	if err := json.Unmarshal(raw, &name); err != nil {
+	var str string
+	if err := json.Unmarshal(raw, &str); err != nil {
 		return "", fmt.Errorf("failed to unmarshal json: %w", err)
 	}
 
-	return name, nil
+	return str, nil
+}
+func extTypeName(extPropValue interface{}) (string, error) {
+	return extString(extPropValue)
+}
+
+func extParseGoFieldName(extPropValue interface{}) (string, error) {
+	return extString(extPropValue)
 }
 
 func extParseOmitEmpty(extPropValue interface{}) (bool, error) {

pkg/codegen/schema.go

@@ -432,7 +432,15 @@ func GenFieldsFromProperties(props []Property) []string {
 			}
 			field += fmt.Sprintf("%s\n", StringToGoComment(p.Description))
 		}
-		field += fmt.Sprintf("    %s %s", p.GoFieldName(), p.GoTypeDef())
+
+		goFieldName := p.GoFieldName()
+		if _, ok := p.ExtensionProps.Extensions[extGoFieldName]; ok {
+			if extGoFieldName, err := extParseGoFieldName(p.ExtensionProps.Extensions[extGoFieldName]); err == nil {
+				goFieldName = extGoFieldName
+			}
+		}
+
+		field += fmt.Sprintf("    %s %s", goFieldName, p.GoTypeDef())
 
 		// Support x-omitempty
 		omitEmpty := true