[Feature][Java/Spring] Support Discriminator Based OneOf Interface

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

@@ -840,7 +840,7 @@ public void postProcessParameter(CodegenParameter parameter) {
     @Override
     @SuppressWarnings("unused")
     public void preprocessOpenAPI(OpenAPI openAPI) {
-        if (useOneOfInterfaces) {
+        if (useOneOfInterfaces && openAPI.getComponents() != null) {
             // we process the openapi schema here to find oneOf schemas and create interface models for them
             Map<String, Schema> schemas = new HashMap<>(openAPI.getComponents().getSchemas());
             if (schemas == null) {

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

@@ -1235,6 +1235,7 @@ public CodegenModel fromModel(String name, Schema model) {
         if (codegenModel.discriminator != null && additionalProperties.containsKey(JACKSON)) {
             codegenModel.imports.add("JsonSubTypes");
             codegenModel.imports.add("JsonTypeInfo");
+            codegenModel.imports.add("JsonTypeName");
         }
         if (allDefinitions != null && codegenModel.parentSchema != null && codegenModel.hasEnums) {
             final Schema parentModel = allDefinitions.get(codegenModel.parentSchema);
@@ -1316,6 +1317,16 @@ public Map<String, Object> postProcessModels(Map<String, Object> objs) {
             }
         }
 
+        // add x-implements for serializable to all models
+        List<Map<String, Object>> models = (List<Map<String, Object>>) objs.get("models");
+        for (Map<String, Object> mo : models) {
+            CodegenModel cm = (CodegenModel) mo.get("model");
+            if (this.serializableModel) {
+                cm.getVendorExtensions().putIfAbsent("x-implements", new ArrayList<String>());
+                ((ArrayList<String>) cm.getVendorExtensions().get("x-implements")).add("Serializable");
+            }
+        }
+
         return postProcessModelsEnum(objs);
     }
 
@@ -1989,4 +2000,16 @@ protected void addAdditionPropertiesToCodeGenModel(CodegenModel codegenModel, Sc
         }
     }
 
+    @Override
+    public void addImportsToOneOfInterface(List<Map<String, String>> imports) {
+        if (additionalProperties.containsKey(JACKSON)) {
+            for (String i : Arrays.asList("JsonSubTypes", "JsonTypeInfo", "JsonTypeName")) {
+                Map<String, String> oneImport = new HashMap<>();
+                oneImport.put("import", importMapping.get(i));
+                if (!imports.contains(oneImport)) {
+                    imports.add(oneImport);
+                }
+            }
+        }
+    }
 }

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

@@ -896,9 +896,6 @@ public Map<String, Object> postProcessModels(Map<String, Object> objs) {
             if (this.parcelableModel) {
                 ((ArrayList<String>) cm.getVendorExtensions().get("x-implements")).add("Parcelable");
             }
-            if (this.serializableModel) {
-                ((ArrayList<String>) cm.getVendorExtensions().get("x-implements")).add("Serializable");
-            }
         }
 
         return objs;
@@ -1036,14 +1033,4 @@ public String toApiVarName(String name) {
         return apiVarName;
     }
 
-    @Override
-    public void addImportsToOneOfInterface(List<Map<String, String>> imports) {
-        for (String i : Arrays.asList("JsonSubTypes", "JsonTypeInfo")) {
-            Map<String, String> oneImport = new HashMap<>();
-            oneImport.put("import", importMapping.get(i));
-            if (!imports.contains(oneImport)) {
-                imports.add(oneImport);
-            }
-        }
-    }
 }

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

@@ -285,6 +285,8 @@ public void processOpts() {
         }
 
         super.processOpts();
+        useOneOfInterfaces = true;
+        legacyDiscriminatorBehavior = false;
 
         if (DocumentationProvider.SPRINGFOX.equals(getDocumentationProvider())) {
             LOGGER.warn("The springfox documentation provider is deprecated for removal. Use the springdoc provider instead.");

modules/openapi-generator/src/main/resources/JavaSpring/model.mustache

@@ -46,7 +46,7 @@ import javax.annotation.Generated;
 {{>enumOuterClass}}
 {{/isEnum}}
 {{^isEnum}}
-{{>pojo}}
+{{#vendorExtensions.x-is-one-of-interface}}{{>oneof_interface}}{{/vendorExtensions.x-is-one-of-interface}}{{^vendorExtensions.x-is-one-of-interface}}{{>pojo}}{{/vendorExtensions.x-is-one-of-interface}}
 {{/isEnum}}
 {{/model}}
 {{/models}}

modules/openapi-generator/src/main/resources/JavaSpring/oneof_interface.mustache

@@ -0,0 +1,13 @@
+{{>additionalModelTypeAnnotations}}
+{{#withXml}}
+{{>xmlAnnotation}}
+{{/withXml}}
+{{#discriminator}}
+{{>typeInfoAnnotation}}
+{{/discriminator}}
+{{>generatedAnnotation}}
+public interface {{classname}}{{#vendorExtensions.x-implements}}{{#-first}} extends {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
+    {{#discriminator}}
+    public {{propertyType}} {{propertyGetter}}();
+    {{/discriminator}}
+}

modules/openapi-generator/src/main/resources/JavaSpring/pojo.mustache

@@ -22,7 +22,7 @@
 {{>xmlAnnotation}}
 {{/withXml}}
 {{>generatedAnnotation}}
-public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}}{{^parent}}{{#hateoas}}extends RepresentationModel<{{classname}}> {{/hateoas}}{{/parent}} {{#serializableModel}}implements Serializable{{/serializableModel}} {
+public class {{classname}}{{#parent}} extends {{{parent}}}{{/parent}}{{^parent}}{{#hateoas}} extends RepresentationModel<{{classname}}> {{/hateoas}}{{/parent}}{{#vendorExtensions.x-implements}}{{#-first}} implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
 {{#serializableModel}}
 
   private static final long serialVersionUID = 1L;

modules/openapi-generator/src/main/resources/JavaSpring/typeInfoAnnotation.mustache

@@ -1,7 +1,17 @@
 {{#jackson}}
+{{#discriminator.mappedModels}}
+{{#-first}}
 @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.EXISTING_PROPERTY, property = "{{{discriminator.propertyBaseName}}}", visible = true)
 @JsonSubTypes({
-  {{#discriminator.mappedModels}}
-  @JsonSubTypes.Type(value = {{modelName}}.class, name = "{{^vendorExtensions.x-discriminator-value}}{{mappingName}}{{/vendorExtensions.x-discriminator-value}}{{#vendorExtensions.x-discriminator-value}}{{{vendorExtensions.x-discriminator-value}}}{{/vendorExtensions.x-discriminator-value}}"),
-  {{/discriminator.mappedModels}}
-}){{/jackson}}
+{{/-first}}
+  {{^vendorExtensions.x-discriminator-value}}
+  @JsonSubTypes.Type(value = {{modelName}}.class, name = "{{{mappingName}}}"){{^-last}},{{/-last}}
+  {{/vendorExtensions.x-discriminator-value}}
+  {{#vendorExtensions.x-discriminator-value}}
+  @JsonSubTypes.Type(value = {{modelName}}.class, name = "{{{vendorExtensions.x-discriminator-value}}}"){{^-last}},{{/-last}}
+  {{/vendorExtensions.x-discriminator-value}}
+{{#-last}}
+})
+{{/-last}}
+{{/discriminator.mappedModels}}
+{{/jackson}}

modules/openapi-generator/src/test/java/org/openapitools/codegen/java/spring/SpringCodegenTest.java

@@ -860,6 +860,44 @@ public void shouldNotAddNotNullOnReadOnlyAttributes() throws IOException {
 
     }
 
+    @Test
+    public void oneOf_5381() throws IOException {
+        File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
+        output.deleteOnExit();
+        String outputPath = output.getAbsolutePath().replace('\\', '/');
+        OpenAPI openAPI = new OpenAPIParser()
+            .readLocation("src/test/resources/3_0/issue_5381.yaml", null, new ParseOptions()).getOpenAPI();
+
+        SpringCodegen codegen = new SpringCodegen();
+        codegen.setOutputDir(output.getAbsolutePath());
+        codegen.additionalProperties().put(CXFServerFeatures.LOAD_TEST_DATA_FROM_FILE, "true");
+        codegen.setUseOneOfInterfaces(true);
+
+        ClientOptInput input = new ClientOptInput();
+        input.openAPI(openAPI);
+        input.config(codegen);
+
+        DefaultGenerator generator = new DefaultGenerator();
+        codegen.setHateoas(true);
+        generator.setGeneratorPropertyDefault(CodegenConstants.MODELS, "true");
+        //generator.setGeneratorPropertyDefault(CodegenConstants.USE_ONEOF_DISCRIMINATOR_LOOKUP, "true");
+        generator.setGeneratorPropertyDefault(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "false");
+
+        codegen.setUseOneOfInterfaces(true);
+        codegen.setLegacyDiscriminatorBehavior(false);
+
+        generator.setGeneratorPropertyDefault(CodegenConstants.MODEL_TESTS, "false");
+        generator.setGeneratorPropertyDefault(CodegenConstants.MODEL_DOCS, "false");
+        generator.setGeneratorPropertyDefault(CodegenConstants.APIS, "true");
+        generator.setGeneratorPropertyDefault(CodegenConstants.SUPPORTING_FILES, "false");
+
+        generator.opts(input).generate();
+
+        assertFileContains(Paths.get(outputPath + "/src/main/java/org/openapitools/model/Foo.java"), "public class Foo implements FooRefOrValue");
+        assertFileContains(Paths.get(outputPath + "/src/main/java/org/openapitools/model/FooRef.java"), "public class FooRef implements FooRefOrValue");
+        assertFileContains(Paths.get(outputPath + "/src/main/java/org/openapitools/model/FooRefOrValue.java"), "public interface FooRefOrValue");
+    }
+
     @Test
     public void testTypeMappings() {
         final SpringCodegen codegen = new SpringCodegen();

modules/openapi-generator/src/test/resources/3_0/issue_5381.yaml

@@ -0,0 +1,134 @@
+openapi: 3.0.1
+info:
+  title: ByRefOrValue
+  description: >
+    This tests for a oneOf interface representation
+  version: 0.0.1
+servers:
+  - url: "http://localhost:8080"
+tags:
+  - name: Foo
+paths:
+  /foo:
+    get:
+      tags:
+        - Foo
+      summary: GET all Foos
+      operationId: getAllFoos
+      responses:
+        '200':
+          $ref: '#/components/responses/200FooArray'
+    post:
+      tags:
+        - Foo
+      summary: Create a Foo
+      operationId: createFoo
+      requestBody:
+        $ref: '#/components/requestBodies/Foo'
+      responses:
+        '201':
+          $ref: '#/components/responses/201Foo'
+
+components:
+  schemas:
+    Entity:
+      type: object
+      allOf:
+        - "$ref": "#/components/schemas/Addressable"
+        - "$ref": "#/components/schemas/Extensible"
+
+    EntityRef:
+      description: Entity reference schema to be use for all entityRef class.
+      type: object
+      properties:
+        name:
+          type: string
+          description: Name of the related entity.
+        '@referredType':
+          type: string
+          description: The actual type of the target instance when needed for disambiguation.
+      allOf:
+        - $ref: '#/components/schemas/Addressable'
+        - "$ref": "#/components/schemas/Extensible"
+
+
+    Addressable:
+      type: object
+      properties:
+        href:
+          type: string
+          description: Hyperlink reference
+        id:
+          type: string
+          description: unique identifier
+      description: Base schema for adressable entities
+    Extensible:
+      type: object
+      properties:
+        "@schemaLocation":
+          type: string
+          description: A URI to a JSON-Schema file that defines additional attributes
+            and relationships
+        "@baseType":
+          type: string
+          description: When sub-classing, this defines the super-class
+        "@type":
+          type: string
+          description: When sub-classing, this defines the sub-class Extensible name
+      required:
+        - '@type'
+
+    FooRefOrValue:
+      type: object
+      oneOf:
+        - $ref: "#/components/schemas/Foo"
+        - $ref: "#/components/schemas/FooRef"
+      discriminator:
+        propertyName: "@type"
+        mapping:
+          Foo: "#/components/schemas/Foo"
+          FooRef: "#/components/schemas/FooRef"
+
+    Foo:
+      type: object
+      properties:
+        fooPropA:
+          type: string
+        fooPropB:
+          type: string
+      allOf:
+        - $ref: '#/components/schemas/Entity'
+
+    FooRef:
+      type: object
+      properties:
+        foorefPropA:
+          type: string
+      allOf:
+        - $ref: '#/components/schemas/EntityRef'
+
+  requestBodies:
+    Foo:
+      description: The Foo to be created
+      content:
+        application/json;charset=utf-8:
+          schema:
+            $ref: '#/components/schemas/Foo'
+  responses:
+    '204':
+      description: Deleted
+      content: { }
+    201Foo:
+      description: Error
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/FooRefOrValue'
+    200FooArray:
+      description: Success
+      content:
+        application/json;charset=utf-8:
+          schema:
+            type: array
+            items:
+              $ref: '#/components/schemas/FooRefOrValue'