[kotlin-spring][server] Feat: Allow implementation of arbitrary interface in DTOs (similar to x-implements from java-spring)

.github/workflows/samples-kotlin-server.yaml

@@ -38,6 +38,7 @@ jobs:
           - samples/server/petstore/kotlin-springboot-source-swagger1
           - samples/server/petstore/kotlin-springboot-source-swagger2
           - samples/server/petstore/kotlin-springboot-springfox
+          - samples/server/petstore/kotlin-springboot-x-kotlin-implements
           - samples/server/petstore/kotlin-server/ktor
           - samples/server/petstore/kotlin-server/ktor2
           - samples/server/petstore/kotlin-server/jaxrs-spec

bin/configs/kotlin-spring-boot-x-kotlin-implements.yaml

@@ -0,0 +1,14 @@
+generatorName: kotlin-spring
+outputDir: samples/server/petstore/kotlin-springboot-x-kotlin-implements
+library: spring-boot
+inputSpec: modules/openapi-generator/src/test/resources/3_0/kotlin/petstore-with-x-kotlin-implements.yaml
+templateDir: modules/openapi-generator/src/main/resources/kotlin-spring
+additionalProperties:
+  documentationProvider: none
+  annotationLibrary: none
+  useSwaggerUI: "false"
+  serviceImplementation: "false"
+  skipDefaultInterface: "true"
+  interfaceOnly: "true"
+  serializableModel: "true"
+  beanValidations: "true"

docs/generators/kotlin-spring.md

@@ -67,6 +67,8 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |x-discriminator-value|Used with model inheritance to specify value for discriminator that identifies current model|MODEL|
 |x-field-extra-annotation|List of custom annotations to be added to property|FIELD, OPERATION_PARAMETER|null
 |x-pattern-message|Add this property whenever you need to customize the invalidation error message for the regex pattern of a variable|FIELD, OPERATION_PARAMETER|null
+|x-kotlin-implements|Ability to specify interfaces that model must implement|MODEL|empty array
+|x-kotlin-implements-fields|Specify attributes that are implemented by the interface(s) added via `x-kotlin-implements`|MODEL|empty array
 
 
 ## IMPORT MAPPING

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

@@ -10,6 +10,8 @@
 public enum VendorExtension {
 
     X_IMPLEMENTS("x-implements", ExtensionLevel.MODEL, "Ability to specify interfaces that model must implements", "empty array"),
+    X_KOTLIN_IMPLEMENTS("x-kotlin-implements", ExtensionLevel.MODEL, "Ability to specify interfaces that model must implement", "empty array"),
+    X_KOTLIN_IMPLEMENTS_FIELDS("x-kotlin-implements-fields", ExtensionLevel.MODEL, "Specify attributes that are implemented by the interface(s) added via `x-kotlin-implements`", "empty array"),
     X_SPRING_PAGINATED("x-spring-paginated", ExtensionLevel.OPERATION, "Add `org.springframework.data.domain.Pageable` to controller method. Can be used to handle `page`, `size` and `sort` query parameters. If these query parameters are also specified in the operation spec, they will be removed from the controller method as their values can be obtained from the `Pageable` object.", "false"),
     X_SPRING_PROVIDE_ARGS("x-spring-provide-args", ExtensionLevel.OPERATION, "Allows adding additional hidden parameters in the API specification to allow access to content such as header values or properties", "empty array"),
     X_DISCRIMINATOR_VALUE("x-discriminator-value", ExtensionLevel.MODEL, "Used with model inheritance to specify value for discriminator that identifies current model", ""),

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

@@ -835,6 +835,16 @@ protected boolean needToImport(String type) {
     @Override
     public CodegenModel fromModel(String name, Schema schema) {
         CodegenModel m = super.fromModel(name, schema);
+        List<String> implementedInterfacesClasses = (List<String>) m.getVendorExtensions().getOrDefault(VendorExtension.X_KOTLIN_IMPLEMENTS.getName(), List.of());
+        List<String> implementedInterfacesFields = Optional.ofNullable((List<String>) m.getVendorExtensions().get(VendorExtension.X_KOTLIN_IMPLEMENTS_FIELDS.getName()))
+                .map(xKotlinImplementsFields -> {
+                    if (implementedInterfacesClasses.isEmpty() && !xKotlinImplementsFields.isEmpty()) {
+                        LOGGER.warn("Annotating {} with {} without {} is not supported. {} will be ignored.",
+                                name, VendorExtension.X_KOTLIN_IMPLEMENTS_FIELDS.getName(), VendorExtension.X_KOTLIN_IMPLEMENTS.getName(),
+                                VendorExtension.X_KOTLIN_IMPLEMENTS_FIELDS.getName());
+                    }
+                    return xKotlinImplementsFields;
+                }).orElse(List.of());
         m.optionalVars = m.optionalVars.stream().distinct().collect(Collectors.toList());
         // Update allVars/requiredVars/optionalVars with isInherited
         // Each of these lists contains elements that are similar, but they are all cloned
@@ -850,7 +860,9 @@ public CodegenModel fromModel(String name, Schema schema) {
         // Update any other vars (requiredVars, optionalVars)
         Stream.of(m.requiredVars, m.optionalVars)
                 .flatMap(List::stream)
-                .filter(p -> allVarsMap.containsKey(p.baseName))
+                .filter(p -> allVarsMap.containsKey(p.baseName)
+                             || implementedInterfacesFields.contains(p.baseName)
+                )
                 .forEach(p -> p.isInherited = true);
         return m;
     }

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

@@ -1012,6 +1012,8 @@ public List<VendorExtension> getSupportedVendorExtensions() {
         extensions.add(VendorExtension.X_DISCRIMINATOR_VALUE);
         extensions.add(VendorExtension.X_FIELD_EXTRA_ANNOTATION);
         extensions.add(VendorExtension.X_PATTERN_MESSAGE);
+        extensions.add(VendorExtension.X_KOTLIN_IMPLEMENTS);
+        extensions.add(VendorExtension.X_KOTLIN_IMPLEMENTS_FIELDS);
         return extensions;
     }
 

modules/openapi-generator/src/main/resources/kotlin-spring/dataClass.mustache

@@ -17,7 +17,34 @@
 {{/-last}}{{/requiredVars}}{{#hasRequired}}{{#hasOptional}},
 {{/hasOptional}}{{/hasRequired}}{{#optionalVars}}{{>dataClassOptVar}}{{^-last}},
 {{/-last}}{{/optionalVars}}
-    ) {{/discriminator}}{{#parent}}: {{{.}}}{{#serializableModel}}, Serializable{{/serializableModel}}{{/parent}}{{^parent}}{{#serializableModel}}: Serializable{{/serializableModel}}{{/parent}}{
+){{/discriminator}}{{! no newline
+}}{{#parent}} : {{{.}}}{{! no newline
+    }}{{#serializableModel}}{{! no newline
+      }}{{^vendorExtensions.x-kotlin-implements}}, Serializable{{/vendorExtensions.x-kotlin-implements}}{{! no newline
+      }}{{#vendorExtensions.x-kotlin-implements}}, Serializable, {{! no newline
+      }}{{#-first}} {{{.}}}{{/-first}}{{! no newline
+      }}{{^-first}}, {{{.}}}{{/-first}}{{! no newline
+      }}{{/vendorExtensions.x-kotlin-implements}}{{! no newline
+  }}{{/serializableModel}}{{! no newline
+  }}{{^serializableModel}}{{! no newline
+      }}{{#vendorExtensions.x-kotlin-implements}}, {{{.}}}{{/vendorExtensions.x-kotlin-implements}}{{! no newline
+  }}{{/serializableModel}}{{! no newline
+}}{{/parent}}{{! no newline
+}}{{^parent}}{{! no newline
+  }}{{#serializableModel}}{{! no newline
+      }}{{^vendorExtensions.x-kotlin-implements}} : Serializable{{/vendorExtensions.x-kotlin-implements}}{{! no newline
+      }}{{#vendorExtensions.x-kotlin-implements}}{{! no newline
+      }}{{#-first}} : Serializable, {{{.}}}{{/-first}}{{! no newline
+      }}{{^-first}}, {{{.}}}{{/-first}}{{! no newline
+      }}{{/vendorExtensions.x-kotlin-implements}}{{! no newline
+  }}{{/serializableModel}}{{! no newline
+  }}{{^serializableModel}}{{! no newline
+    }}{{#vendorExtensions.x-kotlin-implements}}{{! no newline
+    }}{{#-first}} : {{{.}}}{{/-first}}{{! no newline
+      }}{{^-first}}, {{{.}}}{{/-first}}{{! no newline
+    }}{{/vendorExtensions.x-kotlin-implements}}{{! no newline
+  }}{{/serializableModel}}{{! no newline
+}}{{/parent}} {
 {{#discriminator}}
     {{#requiredVars}}
         {{>interfaceReqVar}}{{! prevent indent}}

modules/openapi-generator/src/main/resources/kotlin-spring/enumClass.mustache

@@ -2,7 +2,7 @@
 * {{{description}}}
 * Values: {{#allowableValues}}{{#enumVars}}{{&name}}{{^-last}},{{/-last}}{{/enumVars}}{{/allowableValues}}
 */
-enum class {{classname}}(@get:JsonValue val value: {{dataType}}) {
+enum class {{classname}}(@get:JsonValue val value: {{dataType}}) {{#vendorExtensions.x-kotlin-implements}}{{#-first}}: {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}} {{/vendorExtensions.x-kotlin-implements}}{
 {{#allowableValues}}{{#enumVars}}
     {{&name}}({{{value}}}){{^-last}},{{/-last}}{{/enumVars}}{{/allowableValues}};
 

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

@@ -946,10 +946,80 @@ public void generateSerializableModel() throws Exception {
 
         generator.opts(input).generate();
 
+        Path path = Paths.get(outputPath + "/src/main/kotlin/org/openapitools/model/Pet.kt");
         assertFileContains(
-                Paths.get(outputPath + "/src/main/kotlin/org/openapitools/model/Pet.kt"),
+                path,
                 "import java.io.Serializable",
-                ") : Serializable{",
+                ") : Serializable {",
+                "private const val serialVersionUID: kotlin.Long = 1"
+        );
+    }
+    @Test
+    public void generateSerializableModelWithXimplements() throws Exception {
+        File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
+        output.deleteOnExit();
+        String outputPath = output.getAbsolutePath().replace('\\', '/');
+
+        KotlinSpringServerCodegen codegen = new KotlinSpringServerCodegen();
+        codegen.setOutputDir(output.getAbsolutePath());
+        codegen.additionalProperties().put(CodegenConstants.SERIALIZABLE_MODEL, true);
+
+        ClientOptInput input = new ClientOptInput()
+                .openAPI(TestUtils.parseSpec("src/test/resources/3_0/kotlin/petstore-with-x-kotlin-implements.yaml"))
+                .config(codegen);
+        DefaultGenerator generator = new DefaultGenerator();
+
+        generator.setGeneratorPropertyDefault(CodegenConstants.MODELS, "true");
+        generator.setGeneratorPropertyDefault(CodegenConstants.MODEL_TESTS, "false");
+        generator.setGeneratorPropertyDefault(CodegenConstants.MODEL_DOCS, "false");
+        generator.setGeneratorPropertyDefault(CodegenConstants.APIS, "false");
+        generator.setGeneratorPropertyDefault(CodegenConstants.SUPPORTING_FILES, "false");
+
+        generator.opts(input).generate();
+
+        Path path = Paths.get(outputPath + "/src/main/kotlin/org/openapitools/model/Dog.kt");
+        assertFileContains(
+                path,
+                "import java.io.Serializable",
+                "@get:JsonProperty(\"likesFetch\", required = true) override val likesFetch: kotlin.Boolean,",
+                ") : Pet, Serializable,  com.some.pack.Fetchable {",
+                "private const val serialVersionUID: kotlin.Long = 1"
+        );
+    }
+
+    @Test
+    public void generateNonSerializableModelWithXimplements() throws Exception {
+        File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
+        output.deleteOnExit();
+        String outputPath = output.getAbsolutePath().replace('\\', '/');
+
+        KotlinSpringServerCodegen codegen = new KotlinSpringServerCodegen();
+        codegen.setOutputDir(output.getAbsolutePath());
+
+        ClientOptInput input = new ClientOptInput()
+                .openAPI(TestUtils.parseSpec("src/test/resources/3_0/kotlin/petstore-with-x-kotlin-implements.yaml"))
+                .config(codegen);
+        DefaultGenerator generator = new DefaultGenerator();
+
+        generator.setGeneratorPropertyDefault(CodegenConstants.MODELS, "true");
+        generator.setGeneratorPropertyDefault(CodegenConstants.MODEL_TESTS, "false");
+        generator.setGeneratorPropertyDefault(CodegenConstants.MODEL_DOCS, "false");
+        generator.setGeneratorPropertyDefault(CodegenConstants.APIS, "false");
+        generator.setGeneratorPropertyDefault(CodegenConstants.SUPPORTING_FILES, "false");
+
+        generator.opts(input).generate();
+
+        Path path = Paths.get(outputPath + "/src/main/kotlin/org/openapitools/model/Dog.kt");
+        assertFileContains(
+                path,
+                "@get:JsonProperty(\"likesFetch\", required = true) override val likesFetch: kotlin.Boolean,",
+                ") : Pet, com.some.pack.Fetchable {"
+        );
+        assertFileNotContains(
+                path,
+                "import java.io.Serializable",
+                ") : Pet, Serializable,  com.some.pack.Fetchable {",
+                ") : Pet, Serializable {",
                 "private const val serialVersionUID: kotlin.Long = 1"
         );
     }