feat(websockets): allow manual acknowledgement handling with @Ack() decorator

integration/websockets/e2e/gateway-ack.spec.ts

@@ -41,5 +41,38 @@ describe('WebSocketGateway (ack)', () => {
     );
   });
 
+  it('should handle manual ack for async operations when @Ack() is used (success case)', async () => {
+    app = await createNestApp(AckGateway);
+    await app.listen(3000);
+
+    ws = io('http://localhost:8080');
+    const payload = { shouldSucceed: true };
+
+    await new Promise<void>(resolve =>
+      ws.emit('manual-ack', payload, response => {
+        expect(response).to.eql({ status: 'success', data: payload });
+        resolve();
+      }),
+    );
+  });
+
+  it('should handle manual ack for async operations when @Ack() is used (error case)', async () => {
+    app = await createNestApp(AckGateway);
+    await app.listen(3000);
+
+    ws = io('http://localhost:8080');
+    const payload = { shouldSucceed: false };
+
+    await new Promise<void>(resolve =>
+      ws.emit('manual-ack', payload, response => {
+        expect(response).to.eql({
+          status: 'error',
+          message: 'Operation failed',
+        });
+        resolve();
+      }),
+    );
+  });
+
   afterEach(() => app.close());
 });

integration/websockets/src/ack.gateway.ts

@@ -1,9 +1,29 @@
-import { SubscribeMessage, WebSocketGateway } from '@nestjs/websockets';
+import {
+  Ack,
+  MessageBody,
+  SubscribeMessage,
+  WebSocketGateway,
+} from '@nestjs/websockets';
 
 @WebSocketGateway(8080)
 export class AckGateway {
   @SubscribeMessage('push')
   onPush() {
     return 'pong';
   }
+
+  @SubscribeMessage('manual-ack')
+  async handleManualAck(
+    @MessageBody() data: any,
+    @Ack() ack: (response: any) => void,
+  ) {
+    await new Promise(resolve => setTimeout(resolve, 20));
+
+    if (data.shouldSucceed) {
+      ack({ status: 'success', data });
+    } else {
+      ack({ status: 'error', message: 'Operation failed' });
+    }
+    return { status: 'ignored' };
+  }
 }

packages/common/enums/route-paramtypes.enum.ts

@@ -12,4 +12,5 @@ export enum RouteParamtypes {
   HOST = 10,
   IP = 11,
   RAW_BODY = 12,
+  ACK = 13,
 }

packages/common/interfaces/websockets/web-socket-adapter.interface.ts

@@ -6,6 +6,7 @@ import { Observable } from 'rxjs';
 export interface WsMessageHandler<T = string> {
   message: T;
   callback: (...args: any[]) => Observable<any> | Promise<any>;
+  isAckHandledManually: boolean;
 }
 
 /**

packages/platform-socket.io/adapters/io-adapter.ts

@@ -44,22 +44,24 @@ export class IoAdapter extends AbstractWsAdapter {
       first(),
     );
 
-    handlers.forEach(({ message, callback }) => {
+    handlers.forEach(({ message, callback, isAckHandledManually }) => {
       const source$ = fromEvent(socket, message).pipe(
         mergeMap((payload: any) => {
           const { data, ack } = this.mapPayload(payload);
           return transform(callback(data, ack)).pipe(
             filter((response: any) => !isNil(response)),
-            map((response: any) => [response, ack]),
+            map((response: any) => [response, ack, isAckHandledManually]),
           );
         }),
         takeUntil(disconnect$),
       );
-      source$.subscribe(([response, ack]) => {
+      source$.subscribe(([response, ack, isAckHandledManually]) => {
         if (response.event) {
           return socket.emit(response.event, response.data);
         }
-        isFunction(ack) && ack(response);
+        if (!isAckHandledManually && isFunction(ack)) {
+          ack(response);
+        }
       });
     });
   }

packages/websockets/context/ws-metadata-constants.ts

@@ -1,6 +1,7 @@
 import { WsParamtype } from '../enums/ws-paramtype.enum';
 
 export const DEFAULT_CALLBACK_METADATA = {
+  [`${WsParamtype.ACK}:2`]: { index: 2, data: undefined, pipes: [] },
   [`${WsParamtype.PAYLOAD}:1`]: { index: 1, data: undefined, pipes: [] },
   [`${WsParamtype.SOCKET}:0`]: { index: 0, data: undefined, pipes: [] },
 };

packages/websockets/decorators/ack.decorator.ts

@@ -0,0 +1,28 @@
+import { WsParamtype } from '../enums/ws-paramtype.enum';
+import { createPipesWsParamDecorator } from '../utils/param.utils';
+
+/**
+ * WebSockets `ack` parameter decorator.
+ * Extracts the `ack` callback function from the arguments of a ws event.
+ *
+ * This decorator signals to the framework that the `ack` callback will be
+ * handled manually within the method, preventing the framework from
+ * automatically sending an acknowledgement based on the return value.
+ *
+ * @example
+ * ```typescript
+ * @SubscribeMessage('events')
+ * onEvent(
+ *   @MessageBody() data: string,
+ *   @Ack() ack: (response: any) => void
+ * ) {
+ *   // Manually call the ack callback
+ *   ack({ status: 'ok' });
+ * }
+ * ```
+ *
+ * @publicApi
+ */
+export function Ack(): ParameterDecorator {
+  return createPipesWsParamDecorator(WsParamtype.ACK)();
+}

packages/websockets/decorators/index.ts

@@ -3,3 +3,4 @@ export * from './gateway-server.decorator';
 export * from './message-body.decorator';
 export * from './socket-gateway.decorator';
 export * from './subscribe-message.decorator';
+export * from './ack.decorator';

packages/websockets/enums/ws-paramtype.enum.ts

@@ -3,4 +3,5 @@ import { RouteParamtypes } from '@nestjs/common/enums/route-paramtypes.enum';
 export enum WsParamtype {
   SOCKET = RouteParamtypes.REQUEST,
   PAYLOAD = RouteParamtypes.BODY,
+  ACK = RouteParamtypes.ACK,
 }

packages/websockets/factories/ws-params-factory.ts

@@ -1,3 +1,4 @@
+import { isFunction } from '@nestjs/common/utils/shared.utils';
 import { WsParamtype } from '../enums/ws-paramtype.enum';
 
 export class WsParamsFactory {
@@ -14,6 +15,9 @@ export class WsParamsFactory {
         return args[0];
       case WsParamtype.PAYLOAD:
         return data ? args[1]?.[data] : args[1];
+      case WsParamtype.ACK: {
+        return args.find(arg => isFunction(arg));
+      }
       default:
         return null;
     }

packages/websockets/gateway-metadata-explorer.ts

@@ -5,16 +5,22 @@ import {
   GATEWAY_SERVER_METADATA,
   MESSAGE_MAPPING_METADATA,
   MESSAGE_METADATA,
+  PARAM_ARGS_METADATA,
 } from './constants';
 import { NestGateway } from './interfaces/nest-gateway.interface';
+import { ParamsMetadata } from '@nestjs/core/helpers/interfaces';
+import { WsParamtype } from './enums/ws-paramtype.enum';
+import { ContextUtils } from '@nestjs/core/helpers/context-utils';
 
 export interface MessageMappingProperties {
   message: any;
   methodName: string;
   callback: (...args: any[]) => Observable<any> | Promise<any>;
+  isAckHandledManually: boolean;
 }
 
 export class GatewayMetadataExplorer {
+  private readonly contextUtils = new ContextUtils();
   constructor(private readonly metadataScanner: MetadataScanner) {}
 
   public explore(instance: NestGateway): MessageMappingProperties[] {
@@ -38,13 +44,40 @@ export class GatewayMetadataExplorer {
       return null;
     }
     const message = Reflect.getMetadata(MESSAGE_METADATA, callback);
+    const isAckHandledManually = this.hasAckDecorator(
+      instancePrototype,
+      methodName,
+    );
+
     return {
       callback,
       message,
       methodName,
+      isAckHandledManually,
     };
   }
 
+  private hasAckDecorator(
+    instancePrototype: object,
+    methodName: string,
+  ): boolean {
+    const paramsMetadata: ParamsMetadata = Reflect.getMetadata(
+      PARAM_ARGS_METADATA,
+      instancePrototype.constructor,
+      methodName,
+    );
+
+    if (!paramsMetadata) {
+      return false;
+    }
+    const metadataKeys = Object.keys(paramsMetadata);
+    return metadataKeys.some(key => {
+      const type = this.contextUtils.mapParamType(key);
+
+      return (Number(type) as WsParamtype) === WsParamtype.ACK;
+    });
+  }
+
   public *scanForServerHooks(instance: NestGateway): IterableIterator<string> {
     for (const propertyKey in instance) {
       if (isFunction(propertyKey)) {

packages/websockets/test/decorators/ack.decorator.spec.ts

@@ -0,0 +1,28 @@
+import 'reflect-metadata';
+import { expect } from 'chai';
+import { PARAM_ARGS_METADATA } from '../../constants';
+import { Ack } from '../../decorators/ack.decorator';
+import { WsParamtype } from '../../enums/ws-paramtype.enum';
+
+class AckTest {
+  public test(@Ack() ack: Function) {}
+}
+
+describe('@Ack', () => {
+  it('should enhance class with expected request metadata', () => {
+    const argsMetadata = Reflect.getMetadata(
+      PARAM_ARGS_METADATA,
+      AckTest,
+      'test',
+    );
+
+    const expectedMetadata = {
+      [`${WsParamtype.ACK}:0`]: {
+        index: 0,
+        data: undefined,
+        pipes: [],
+      },
+    };
+    expect(argsMetadata).to.be.eql(expectedMetadata);
+  });
+});

packages/websockets/test/gateway-metadata-explorer.spec.ts

@@ -4,11 +4,13 @@ import { MetadataScanner } from '../../core/metadata-scanner';
 import { WebSocketServer } from '../decorators/gateway-server.decorator';
 import { WebSocketGateway } from '../decorators/socket-gateway.decorator';
 import { SubscribeMessage } from '../decorators/subscribe-message.decorator';
+import { Ack } from '../decorators/ack.decorator';
 import { GatewayMetadataExplorer } from '../gateway-metadata-explorer';
 
 describe('GatewayMetadataExplorer', () => {
   const message = 'test';
   const secMessage = 'test2';
+  const ackMessage = 'ack-test';
 
   @WebSocketGateway()
   class Test {
@@ -28,6 +30,9 @@ describe('GatewayMetadataExplorer', () => {
     @SubscribeMessage(secMessage)
     public testSec() {}
 
+    @SubscribeMessage(ackMessage)
+    public testWithAck(@Ack() ack: Function) {}
+
     public noMessage() {}
   }
   let instance: GatewayMetadataExplorer;
@@ -61,9 +66,22 @@ describe('GatewayMetadataExplorer', () => {
     });
     it(`should return message mapping properties when "isMessageMapping" metadata is not undefined`, () => {
       const metadata = instance.exploreMethodMetadata(test, 'test')!;
-      expect(metadata).to.have.keys(['callback', 'message', 'methodName']);
+      expect(metadata).to.have.keys([
+        'callback',
+        'message',
+        'methodName',
+        'isAckHandledManually',
+      ]);
       expect(metadata.message).to.eql(message);
     });
+    it('should set "isAckHandledManually" property to true when @Ack decorator is used', () => {
+      const metadata = instance.exploreMethodMetadata(test, 'testWithAck')!;
+      expect(metadata.isAckHandledManually).to.be.true;
+    });
+    it('should set "isAckHandledManually" property to false when @Ack decorator is not used', () => {
+      const metadata = instance.exploreMethodMetadata(test, 'test')!;
+      expect(metadata.isAckHandledManually).to.be.false;
+    });
   });
   describe('scanForServerHooks', () => {
     it(`should return properties with @Client decorator`, () => {

packages/websockets/test/web-sockets-controller.spec.ts

@@ -135,6 +135,7 @@ describe('WebSocketsController', () => {
           message: 'message',
           methodName: 'methodName',
           callback: handlerCallback,
+          isAckHandledManually: false,
         },
       ];
       server = { server: 'test' };
@@ -173,6 +174,7 @@ describe('WebSocketsController', () => {
           message: 'message',
           methodName: 'methodName',
           callback: messageHandlerCallback,
+          isAckHandledManually: false,
         },
       ]);
     });
@@ -188,11 +190,13 @@ describe('WebSocketsController', () => {
           methodName: 'findOne',
           message: 'find',
           callback: null!,
+          isAckHandledManually: false,
         },
         {
           methodName: 'create',
           message: 'insert',
           callback: null!,
+          isAckHandledManually: false,
         },
       ];
       const insertEntrypointDefinitionSpy = sinon.spy(
@@ -423,14 +427,40 @@ describe('WebSocketsController', () => {
       client = { on: onSpy, off: onSpy };
 
       handlers = [
-        { message: 'test', callback: { bind: () => 'testCallback' } },
-        { message: 'test2', callback: { bind: () => 'testCallback2' } },
+        {
+          message: 'test',
+          callback: { bind: () => 'testCallback' },
+          isAckHandledManually: true,
+        },
+        {
+          message: 'test2',
+          callback: { bind: () => 'testCallback2' },
+          isAckHandledManually: false,
+        },
       ];
     });
     it('should bind each handler to client', () => {
       instance.subscribeMessages(handlers, client, gateway);
       expect(onSpy.calledTwice).to.be.true;
     });
+    it('should pass "isAckHandledManually" flag to the adapter', () => {
+      const adapter = config.getIoAdapter();
+      const bindMessageHandlersSpy = sinon.spy(adapter, 'bindMessageHandlers');
+
+      instance.subscribeMessages(handlers, client, gateway);
+
+      const handlersPassedToAdapter = bindMessageHandlersSpy.firstCall.args[1];
+
+      expect(handlersPassedToAdapter[0].message).to.equal(handlers[0].message);
+      expect(handlersPassedToAdapter[0].isAckHandledManually).to.equal(
+        handlers[0].isAckHandledManually,
+      );
+
+      expect(handlersPassedToAdapter[1].message).to.equal(handlers[1].message);
+      expect(handlersPassedToAdapter[1].isAckHandledManually).to.equal(
+        handlers[1].isAckHandledManually,
+      );
+    });
   });
   describe('pickResult', () => {
     describe('when deferredResult contains value which', () => {