[kotlin-spring] Adds useFlowForArrayReturnType option for reactive mode (#16130)

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

@@ -34,6 +34,8 @@ jobs:
           - samples/server/petstore/kotlin-springboot-delegate
           - samples/server/petstore/kotlin-springboot-modelMutable
           - samples/server/petstore/kotlin-springboot-reactive
+          - samples/server/petstore/kotlin-springboot-reactive-with-flow
+          - samples/server/petstore/kotlin-springboot-reactive-without-flow
           - samples/server/petstore/kotlin-springboot-source-swagger1
           - samples/server/petstore/kotlin-springboot-source-swagger2
           - samples/server/petstore/kotlin-springboot-springfox

bin/configs/kotlin-spring-boot-reactive-with-flow.yaml

@@ -0,0 +1,13 @@
+generatorName: kotlin-spring
+outputDir: samples/server/petstore/kotlin-springboot-reactive-with-flow
+library: spring-boot
+inputSpec: modules/openapi-generator/src/test/resources/3_0/petstore.yaml
+templateDir: modules/openapi-generator/src/main/resources/kotlin-spring
+additionalProperties:
+  documentationProvider: springdoc
+  annotationLibrary: swagger2
+  useSwaggerUI: "true"
+  serviceImplementation: "true"
+  reactive: "true"
+  beanValidations: "true"
+  useFlowForArrayReturnType: "true"

bin/configs/kotlin-spring-boot-reactive-without-flow.yaml

@@ -0,0 +1,13 @@
+generatorName: kotlin-spring
+outputDir: samples/server/petstore/kotlin-springboot-reactive-without-flow
+library: spring-boot
+inputSpec: modules/openapi-generator/src/test/resources/3_0/petstore.yaml
+templateDir: modules/openapi-generator/src/main/resources/kotlin-spring
+additionalProperties:
+  documentationProvider: springdoc
+  annotationLibrary: swagger2
+  useSwaggerUI: "true"
+  serviceImplementation: "true"
+  reactive: "true"
+  beanValidations: "true"
+  useFlowForArrayReturnType: "false"

docs/generators/kotlin-spring.md

@@ -52,6 +52,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |title|server title name or client service name| |OpenAPI Kotlin Spring|
 |useBeanValidation|Use BeanValidation API annotations to validate data types| |true|
 |useFeignClientUrl|Whether to generate Feign client with url parameter.| |true|
+|useFlowForArrayReturnType|Whether to use Flow for array/collection return types when reactive is enabled. If false, will use List instead.| |true|
 |useSpringBoot3|Generate code and provide dependencies for use with Spring Boot 3.x. (Use jakarta instead of javax in imports). Enabling this option will also enable `useJakartaEe`.| |false|
 |useSwaggerUI|Open the OpenApi specification in swagger-ui. Will also import and configure needed dependencies| |true|
 |useTags|Whether to use tags for creating interface and controller class names| |false|

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

@@ -105,6 +105,7 @@ public class KotlinSpringServerCodegen extends AbstractKotlinCodegen
     public static final String BEAN_QUALIFIERS = "beanQualifiers";
 
     public static final String USE_SPRING_BOOT3 = "useSpringBoot3";
+    public static final String USE_FLOW_FOR_ARRAY_RETURN_TYPE = "useFlowForArrayReturnType";
     public static final String REQUEST_MAPPING_OPTION = "requestMappingMode";
     public static final String USE_REQUEST_MAPPING_ON_CONTROLLER = "useRequestMappingOnController";
     public static final String USE_REQUEST_MAPPING_ON_INTERFACE = "useRequestMappingOnInterface";
@@ -145,6 +146,8 @@ public String getDescription() {
     @Setter private boolean serviceImplementation = false;
     @Getter @Setter
     private boolean reactive = false;
+    @Getter @Setter
+    private boolean useFlowForArrayReturnType = true;
     @Setter private boolean interfaceOnly = false;
     @Setter protected boolean useFeignClientUrl = true;
     @Setter protected boolean useFeignClient = false;
@@ -235,6 +238,7 @@ public KotlinSpringServerCodegen() {
                 "@RestController annotations. May be used to prevent bean names clash if multiple generated libraries" +
                 " (contexts) added to single project.", beanQualifiers);
         addSwitch(USE_SPRING_BOOT3, "Generate code and provide dependencies for use with Spring Boot 3.x. (Use jakarta instead of javax in imports). Enabling this option will also enable `useJakartaEe`.", useSpringBoot3);
+        addSwitch(USE_FLOW_FOR_ARRAY_RETURN_TYPE, "Whether to use Flow for array/collection return types when reactive is enabled. If false, will use List instead.", useFlowForArrayReturnType);
         supportedLibraries.put(SPRING_BOOT, "Spring-boot Server application.");
         supportedLibraries.put(SPRING_CLOUD_LIBRARY,
                 "Spring-Cloud-Feign client with Spring-Boot auto-configured settings.");
@@ -527,10 +531,15 @@ public void processOpts() {
                 this.setReactive(convertPropertyToBoolean(REACTIVE));
                 // spring webflux doesn't support @ControllerAdvice
                 this.setExceptionHandler(false);
+
+                if (additionalProperties.containsKey(USE_FLOW_FOR_ARRAY_RETURN_TYPE)) {
+                    this.setUseFlowForArrayReturnType(convertPropertyToBoolean(USE_FLOW_FOR_ARRAY_RETURN_TYPE));
+                }
             }
         }
         writePropertyBack(REACTIVE, reactive);
         writePropertyBack(EXCEPTION_HANDLER, exceptionHandler);
+        writePropertyBack(USE_FLOW_FOR_ARRAY_RETURN_TYPE, useFlowForArrayReturnType);
 
         if (additionalProperties.containsKey(BEAN_QUALIFIERS) && library.equals(SPRING_BOOT)) {
             this.setBeanQualifiers(convertPropertyToBoolean(BEAN_QUALIFIERS));
@@ -685,7 +694,7 @@ public void processOpts() {
                     supportingFiles.add(new SupportingFile("buildGradleKts.mustache", "build.gradle.kts"));
                 }
                 supportingFiles.add(new SupportingFile("settingsGradle.mustache", "settings.gradle"));
-                
+
                 String gradleWrapperPackage = "gradle.wrapper";
                 supportingFiles.add(new SupportingFile("gradlew.mustache", "", "gradlew"));
                 supportingFiles.add(new SupportingFile("gradlew.bat.mustache", "", "gradlew.bat"));

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

@@ -1 +1 @@
-{{#isMap}}Map<String, {{{returnType}}}>{{/isMap}}{{#isArray}}{{#reactive}}Flow{{/reactive}}{{^reactive}}{{{returnContainer}}}{{/reactive}}<{{{returnType}}}>{{/isArray}}{{^returnContainer}}{{{returnType}}}{{/returnContainer}}
+{{#isMap}}Map<String, {{{returnType}}}>{{/isMap}}{{#isArray}}{{#reactive}}{{#useFlowForArrayReturnType}}Flow{{/useFlowForArrayReturnType}}{{^useFlowForArrayReturnType}}{{{returnContainer}}}{{/useFlowForArrayReturnType}}{{/reactive}}{{^reactive}}{{{returnContainer}}}{{/reactive}}<{{{returnType}}}>{{/isArray}}{{^returnContainer}}{{{returnType}}}{{/returnContainer}}

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

@@ -911,4 +911,230 @@ public void generateSerializableModel() throws Exception {
                 "private const val serialVersionUID: kotlin.Long = 1"
         );
     }
+
+    @Test
+    public void reactiveWithoutFlow() throws Exception {
+        File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
+        KotlinSpringServerCodegen codegen = new KotlinSpringServerCodegen();
+        codegen.setOutputDir(output.getAbsolutePath());
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.REACTIVE, true);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.USE_FLOW_FOR_ARRAY_RETURN_TYPE, false);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.USE_TAGS, true);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.SERVICE_IMPLEMENTATION, true);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.DELEGATE_PATTERN, true);
+
+        List<File> files = new DefaultGenerator()
+            .opts(
+                new ClientOptInput()
+                    .openAPI(TestUtils.parseSpec("src/test/resources/3_0/kotlin/issue16130-add-useFlowForArrayReturnType-param.yaml"))
+                    .config(codegen)
+            )
+            .generate();
+
+        Assertions.assertThat(files).contains(
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1Api.kt"),
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1ApiController.kt"),
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1ApiDelegate.kt"),
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1ApiService.kt")
+        );
+
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiController.kt"),
+                "Flow<kotlin.String>");
+
+        assertFileContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1Api.kt"),
+                "List<kotlin.String>");
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1Api.kt"),
+                "Flow<kotlin.String>");
+
+        assertFileContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiDelegate.kt"),
+                "List<kotlin.String>");
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiDelegate.kt"),
+                "Flow<kotlin.String>");
+
+        assertFileContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiService.kt"),
+                "List<kotlin.String>");
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiService.kt"),
+                "Flow<kotlin.String>");
+    }
+
+    @Test
+    public void reactiveWithFlow() throws Exception {
+        File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
+        KotlinSpringServerCodegen codegen = new KotlinSpringServerCodegen();
+        codegen.setOutputDir(output.getAbsolutePath());
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.REACTIVE, true);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.USE_FLOW_FOR_ARRAY_RETURN_TYPE, true);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.USE_TAGS, true);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.SERVICE_IMPLEMENTATION, true);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.DELEGATE_PATTERN, true);
+
+        List<File> files = new DefaultGenerator()
+            .opts(
+                new ClientOptInput()
+                    .openAPI(TestUtils.parseSpec("src/test/resources/3_0/kotlin/issue16130-add-useFlowForArrayReturnType-param.yaml"))
+                    .config(codegen)
+            )
+            .generate();
+
+        Assertions.assertThat(files).contains(
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1Api.kt"),
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1ApiController.kt"),
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1ApiDelegate.kt"),
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1ApiService.kt")
+        );
+
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiController.kt"),
+                "List<kotlin.String>");
+
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1Api.kt"),
+                "List<kotlin.String>");
+        assertFileContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1Api.kt"),
+                "Flow<kotlin.String>");
+
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiDelegate.kt"),
+                "List<kotlin.String>");
+        assertFileContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiDelegate.kt"),
+                "Flow<kotlin.String>");
+
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiService.kt"),
+                "List<kotlin.String>");
+        assertFileContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiService.kt"),
+                "Flow<kotlin.String>");
+    }
+
+    @Test
+    public void reactiveWithDefaultValueFlow() throws Exception {
+        File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
+        KotlinSpringServerCodegen codegen = new KotlinSpringServerCodegen();
+        codegen.setOutputDir(output.getAbsolutePath());
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.REACTIVE, true);
+        // should use default 'true' instead
+        // codegen.additionalProperties().put(KotlinSpringServerCodegen.USE_FLOW_FOR_ARRAY_RETURN_TYPE, true);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.USE_TAGS, true);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.SERVICE_IMPLEMENTATION, true);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.DELEGATE_PATTERN, true);
+
+        List<File> files = new DefaultGenerator()
+            .opts(
+                new ClientOptInput()
+                    .openAPI(TestUtils.parseSpec("src/test/resources/3_0/kotlin/issue16130-add-useFlowForArrayReturnType-param.yaml"))
+                    .config(codegen)
+            )
+            .generate();
+
+        Assertions.assertThat(files).contains(
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1Api.kt"),
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1ApiController.kt"),
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1ApiDelegate.kt"),
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1ApiService.kt")
+        );
+
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiController.kt"),
+                "List<kotlin.String>");
+
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1Api.kt"),
+                "List<kotlin.String>");
+        assertFileContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1Api.kt"),
+                "Flow<kotlin.String>");
+
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiDelegate.kt"),
+                "List<kotlin.String>");
+        assertFileContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiDelegate.kt"),
+                "Flow<kotlin.String>");
+
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiService.kt"),
+                "List<kotlin.String>");
+        assertFileContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiService.kt"),
+                "Flow<kotlin.String>");
+    }
+
+    @Test
+    public void nonReactiveWithoutFlow() throws Exception {
+        File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
+        KotlinSpringServerCodegen codegen = new KotlinSpringServerCodegen();
+        codegen.setOutputDir(output.getAbsolutePath());
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.REACTIVE, false);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.USE_FLOW_FOR_ARRAY_RETURN_TYPE, false);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.USE_TAGS, true);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.SERVICE_IMPLEMENTATION, true);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.DELEGATE_PATTERN, true);
+
+        List<File> files = new DefaultGenerator()
+            .opts(
+                new ClientOptInput()
+                    .openAPI(TestUtils.parseSpec("src/test/resources/3_0/kotlin/issue16130-add-useFlowForArrayReturnType-param.yaml"))
+                    .config(codegen)
+            )
+            .generate();
+
+        Assertions.assertThat(files).contains(
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1Api.kt"),
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1ApiController.kt"),
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1ApiDelegate.kt"),
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1ApiService.kt")
+        );
+
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiController.kt"),
+                "Flow<kotlin.String>");
+
+        assertFileContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1Api.kt"),
+                "List<kotlin.String>");
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1Api.kt"),
+                "Flow<kotlin.String>");
+
+        assertFileContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiDelegate.kt"),
+                "List<kotlin.String>");
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiDelegate.kt"),
+                "Flow<kotlin.String>");
+
+        assertFileContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiService.kt"),
+                "List<kotlin.String>");
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiService.kt"),
+                "Flow<kotlin.String>");
+    }
+
+    @Test
+    public void nonReactiveWithFlow() throws Exception {
+        File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
+        KotlinSpringServerCodegen codegen = new KotlinSpringServerCodegen();
+        codegen.setOutputDir(output.getAbsolutePath());
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.REACTIVE, false);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.USE_FLOW_FOR_ARRAY_RETURN_TYPE, true);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.USE_TAGS, true);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.SERVICE_IMPLEMENTATION, true);
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.DELEGATE_PATTERN, true);
+
+        List<File> files = new DefaultGenerator()
+            .opts(
+                new ClientOptInput()
+                    .openAPI(TestUtils.parseSpec("src/test/resources/3_0/kotlin/issue16130-add-useFlowForArrayReturnType-param.yaml"))
+                    .config(codegen)
+            )
+            .generate();
+
+        Assertions.assertThat(files).contains(
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1Api.kt"),
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1ApiController.kt"),
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1ApiDelegate.kt"),
+                new File(output, "src/main/kotlin/org/openapitools/api/TestV1ApiService.kt")
+        );
+
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiController.kt"),
+                "Flow<kotlin.String>");
+
+        assertFileContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1Api.kt"),
+                "List<kotlin.String>");
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1Api.kt"),
+                "Flow<kotlin.String>");
+
+        assertFileContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiDelegate.kt"),
+                "List<kotlin.String>");
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiDelegate.kt"),
+                "Flow<kotlin.String>");
+
+        assertFileContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiService.kt"),
+                "List<kotlin.String>");
+        assertFileNotContains(Paths.get(output + "/src/main/kotlin/org/openapitools/api/TestV1ApiService.kt"),
+                "Flow<kotlin.String>");
+    }
 }

modules/openapi-generator/src/test/resources/3_0/kotlin/issue16130-add-useFlowForArrayReturnType-param.yaml

@@ -0,0 +1,20 @@
+openapi: "3.0.1"
+info:
+  title: test
+  version: "1.0"
+
+paths:
+
+  /api/v1/test:
+    get:
+      tags: [Test v1]
+      operationId: test1
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  type: string