create go structs composition from composed schemas

Author: HugoMario

src/main/java/io/swagger/codegen/v3/generators/go/AbstractGoCodegen.java

@@ -1,14 +1,15 @@
 package io.swagger.codegen.v3.generators.go;
 
 import io.swagger.codegen.v3.CliOption;
-import io.swagger.codegen.v3.CodegenConfig;
 import io.swagger.codegen.v3.CodegenConstants;
 import io.swagger.codegen.v3.CodegenContent;
 import io.swagger.codegen.v3.CodegenModel;
 import io.swagger.codegen.v3.CodegenOperation;
 import io.swagger.codegen.v3.CodegenParameter;
 import io.swagger.codegen.v3.CodegenProperty;
+import io.swagger.codegen.v3.ISchemaHandler;
 import io.swagger.codegen.v3.generators.DefaultCodegenConfig;
+import io.swagger.codegen.v3.generators.util.OpenAPIUtil;
 import io.swagger.v3.core.util.Yaml;
 import io.swagger.v3.oas.models.OpenAPI;
 import io.swagger.v3.oas.models.media.ArraySchema;
@@ -267,6 +268,14 @@ public String getTypeDeclaration(Schema schema) {
     @Override
     public String getSchemaType(Schema schema) {
         String schemaType = super.getSchemaType(schema);
+
+        if (schema.get$ref() != null) {
+            final Schema refSchema = OpenAPIUtil.getSchemaFromName(schemaType, this.openAPI);
+            if (refSchema != null && !isObjectSchema(refSchema)) {
+                schemaType = super.getSchemaType(refSchema);
+            }
+        }
+
         String type;
         if(typeMapping.containsKey(schemaType)) {
             type = typeMapping.get(schemaType);
@@ -547,4 +556,9 @@ public CodegenModel fromModel(String name, Schema schema, Map<String, Schema> al
 
         return codegenModel;
     }
+
+    @Override
+    public ISchemaHandler getSchemaHandler() {
+        return new GoSchemaHandler(this);
+    }
 }

src/main/java/io/swagger/codegen/v3/generators/go/GoSchemaHandler.java

@@ -0,0 +1,28 @@
+package io.swagger.codegen.v3.generators.go;
+
+import io.swagger.codegen.v3.CodegenModel;
+import io.swagger.codegen.v3.generators.DefaultCodegenConfig;
+import io.swagger.codegen.v3.generators.SchemaHandler;
+import io.swagger.v3.oas.models.media.Schema;
+import org.apache.commons.lang3.StringUtils;
+
+import java.util.List;
+import java.util.Map;
+
+public class GoSchemaHandler extends SchemaHandler {
+
+    public GoSchemaHandler(DefaultCodegenConfig codegenConfig) {
+        super(codegenConfig);
+    }
+
+    protected void addInterfaces(List<Schema> schemas, CodegenModel composedModel, Map<String, CodegenModel> allModels) {
+        for (Schema interfaceSchema : schemas) {
+            final String ref = interfaceSchema.get$ref();
+            if (StringUtils.isBlank(ref)) {
+                continue;
+            }
+            final String schemaName = ref.substring(ref.lastIndexOf("/") + 1);
+            this.addInterfaceModel(composedModel, allModels.get(codegenConfig.toModelName(schemaName)));
+        }
+    }
+}

src/main/resources/handlebars/go/model.mustache

@@ -19,6 +19,12 @@ const (
 ){{/isEnum}}{{^isEnum}}{{#description}}
 // {{{description}}}{{/description}}
 type {{classname}} struct {
+{{#isComposedModel}}
+    {{#interfaceModels}}
+    {{classname}}
+    {{/interfaceModels}}
+{{/isComposedModel}}
+{{^isComposedModel}}
 {{#vars}}
 {{^@first}}
 {{/@first}}
@@ -27,4 +33,5 @@ type {{classname}} struct {
 {{/description}}
 	{{name}} {{^isEnum}}{{^isPrimitiveType}}{{^isContainer}}{{^isDateTime}}*{{/isDateTime}}{{/isContainer}}{{/isPrimitiveType}}{{/isEnum}}{{{datatype}}} `json:"{{baseName}}{{^required}},omitempty{{/required}}"{{#withXml}} xml:"{{baseName}}"{{/withXml}}`
 {{/vars}}
+{{/isComposedModel}}
 }{{/isEnum}}{{/model}}{{/models}}

src/main/resources/mustache/go/model.mustache

@@ -19,6 +19,12 @@ const (
 ){{/isEnum}}{{^isEnum}}{{#description}}
 // {{{description}}}{{/description}}
 type {{classname}} struct {
+{{#isComposedModel}}
+    {{#interfaceModels}}
+    {{classname}}
+    {{/interfaceModels}}
+{{/isComposedModel}}
+{{^isComposedModel}}
 {{#vars}}
 {{^-first}}
 {{/-first}}
@@ -27,4 +33,5 @@ type {{classname}} struct {
 {{/description}}
 	{{name}} {{^isEnum}}{{^isPrimitiveType}}{{^isContainer}}{{^isDateTime}}*{{/isDateTime}}{{/isContainer}}{{/isPrimitiveType}}{{/isEnum}}{{{datatype}}} `json:"{{baseName}}{{^required}},omitempty{{/required}}"{{#withXml}} xml:"{{baseName}}"{{/withXml}}`
 {{/vars}}
+{{/isComposedModel}}
 }{{/isEnum}}{{/model}}{{/models}}