Add support kotlin Flow as response type. Fixes springdoc#560

Author: bnasslahsen

springdoc-openapi-common/src/main/java/org/springdoc/core/SpringDocUtils.java

@@ -103,5 +103,15 @@ public SpringDocUtils removeAnnotationsToIgnore(Class<?>... classes) {
 		GenericParameterBuilder.removeAnnotationsToIgnore(classes);
 		return this;
 	}
+
+	public SpringDocUtils addFluxWrapperToIgnore(Class<?> cls) {
+		ConverterUtils.addFluxWrapperToIgnore(cls);
+		return this;
+	}
+
+	public SpringDocUtils removeFluxWrapperToIgnore(Class<?> cls) {
+		ConverterUtils.removeFluxWrapperToIgnore(cls);
+		return this;
+	}
 }
 

springdoc-openapi-common/src/main/java/org/springdoc/core/converters/ConverterUtils.java

@@ -33,6 +33,8 @@ public class ConverterUtils {
 
 	private static final List<Class<?>> RESPONSE_TYPES_TO_IGNORE = new ArrayList<>();
 
+	private static final List<Class<?>> FLUX_WRAPPERS_TO_IGNORE = new ArrayList<>();
+
 	static {
 		RESULT_WRAPPERS_TO_IGNORE.add(Callable.class);
 		RESULT_WRAPPERS_TO_IGNORE.add(ResponseEntity.class);
@@ -70,4 +72,18 @@ public static void removeResponseTypeToIgnore(Class<?> classes) {
 		if (RESPONSE_TYPES_TO_IGNORE.containsAll(classesToIgnore))
 			RESPONSE_TYPES_TO_IGNORE.removeAll(Arrays.asList(classes));
 	}
+
+	public static boolean isFluxTypeWrapper(Class<?> rawClass) {
+		return FLUX_WRAPPERS_TO_IGNORE.stream().anyMatch(clazz -> clazz.isAssignableFrom(rawClass));
+	}
+
+	public static void removeFluxWrapperToIgnore(Class<?> classes) {
+		List classesToIgnore = Arrays.asList(classes);
+		if (FLUX_WRAPPERS_TO_IGNORE.containsAll(classesToIgnore))
+			FLUX_WRAPPERS_TO_IGNORE.removeAll(Arrays.asList(classes));
+	}
+
+	public static void addFluxWrapperToIgnore(Class<?> cls) {
+		FLUX_WRAPPERS_TO_IGNORE.add(cls);
+	}
 }

springdoc-openapi-kotlin/src/main/java/org/springdoc/kotlin/SpringDocKotlinConfiguration.java

@@ -22,6 +22,7 @@
 import io.swagger.v3.core.util.Json;
 import kotlin.Deprecated;
 import kotlin.coroutines.Continuation;
+import kotlinx.coroutines.flow.Flow;
 
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.context.annotation.Bean;
@@ -37,7 +38,8 @@ public class SpringDocKotlinConfiguration {
 
 	static {
 		getConfig().addRequestWrapperToIgnore(Continuation.class)
-				.addDeprecatedType(Deprecated.class);
+				.addDeprecatedType(Deprecated.class)
+				.addFluxWrapperToIgnore(Flow.class);
 		Json.mapper().registerModule(new KotlinModule());
 	}
 

springdoc-openapi-kotlin/src/test/kotlin/test/org/springdoc/api/app5/HelloController.kt

@@ -0,0 +1,46 @@
+/*
+ *
+ *  * Copyright 2019-2020 the original author or authors.
+ *  *
+ *  * Licensed under the Apache License, Version 2.0 (the "License");
+ *  * you may not use this file except in compliance with the License.
+ *  * You may obtain a copy of the License at
+ *  *
+ *  *      https://www.apache.org/licenses/LICENSE-2.0
+ *  *
+ *  * Unless required by applicable law or agreed to in writing, software
+ *  * distributed under the License is distributed on an "AS IS" BASIS,
+ *  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  * See the License for the specific language governing permissions and
+ *  * limitations under the License.
+ *
+ */
+
+package test.org.springdoc.api.app5
+
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.flow
+import org.springframework.web.bind.annotation.GetMapping
+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RestController
+
+
+data class Person(
+		val name: String,
+		val nickname: String?
+)
+
+@RestController
+@RequestMapping("/test")
+class HelloController {
+
+	@GetMapping("/")
+	fun foo(): Flow<Int> = flow { // flow builder
+		for (i in 1..3) {
+			delay(100) // pretend we are doing something useful here
+			emit(i) // emit next value
+		}
+	}
+
+}

springdoc-openapi-kotlin/src/test/kotlin/test/org/springdoc/api/app5/SpringDocApp5Test.kt

@@ -0,0 +1,31 @@
+/*
+ *
+ *  * Copyright 2019-2020 the original author or authors.
+ *  *
+ *  * Licensed under the Apache License, Version 2.0 (the "License");
+ *  * you may not use this file except in compliance with the License.
+ *  * You may obtain a copy of the License at
+ *  *
+ *  *      https://www.apache.org/licenses/LICENSE-2.0
+ *  *
+ *  * Unless required by applicable law or agreed to in writing, software
+ *  * distributed under the License is distributed on an "AS IS" BASIS,
+ *  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  * See the License for the specific language governing permissions and
+ *  * limitations under the License.
+ *
+ */
+
+package test.org.springdoc.api.app5
+
+import org.springframework.boot.autoconfigure.SpringBootApplication
+import org.springframework.context.annotation.ComponentScan
+import test.org.springdoc.api.AbstractKotlinSpringDocTest
+
+@ComponentScan(basePackages = ["org.springdoc", "test.org.springdoc.api.app5"])
+class SpringDocApp5Test : AbstractKotlinSpringDocTest() {
+
+	@SpringBootApplication
+	open class DemoApplication
+
+}

springdoc-openapi-kotlin/src/test/resources/results/app5.json

@@ -11,29 +11,23 @@
     }
   ],
   "paths": {
-    "/test": {
+    "/test/": {
       "get": {
         "tags": [
           "hello-controller"
         ],
-        "operationId": "index",
-        "parameters": [
-          {
-            "name": "s",
-            "in": "query",
-            "required": true,
-            "schema": {
-              "$ref": "#/components/schemas/Person"
-            }
-          }
-        ],
+        "operationId": "foo",
         "responses": {
           "200": {
             "description": "default response",
             "content": {
               "*/*": {
                 "schema": {
-                  "$ref": "#/components/schemas/Person"
+                  "type": "array",
+                  "items": {
+                    "type": "integer",
+                    "format": "int32"
+                  }
                 }
               }
             }
@@ -42,22 +36,5 @@
       }
     }
   },
-  "components": {
-    "schemas": {
-      "Person": {
-        "required": [
-          "name"
-        ],
-        "type": "object",
-        "properties": {
-          "name": {
-            "type": "string"
-          },
-          "nickname": {
-            "type": "string"
-          }
-        }
-      }
-    }
-  }
-}
+  "components": {}
+}

springdoc-openapi-webflux-core/src/main/java/org/springdoc/webflux/core/converters/WebFluxSupportConverter.java

@@ -32,21 +32,23 @@
 import reactor.core.publisher.Mono;
 
 import static org.springdoc.core.SpringDocUtils.getConfig;
+import static org.springdoc.core.converters.ConverterUtils.isFluxTypeWrapper;
 import static org.springdoc.core.converters.ConverterUtils.isResponseTypeWrapper;
 
 
 public class WebFluxSupportConverter implements ModelConverter {
 
 	static {
-		getConfig().addResponseWrapperToIgnore(Mono.class);
+		getConfig().addResponseWrapperToIgnore(Mono.class)
+				.addFluxWrapperToIgnore(Flux.class);
 	}
 
 	@Override
 	public Schema resolve(AnnotatedType type, ModelConverterContext context, Iterator<ModelConverter> chain) {
 		JavaType javaType = Json.mapper().constructType(type.getType());
 		if (javaType != null) {
 			Class<?> cls = javaType.getRawClass();
-			if (Flux.class.isAssignableFrom(cls)) {
+			if (isFluxTypeWrapper(cls)) {
 				JavaType innerType = javaType.getBindings().getBoundType(0);
 				if (innerType == null)
 					return new StringSchema();