NestJS - WebsocketGateway 中的 ValidationPipe 返回内部服务器错误

使用NestJS的WebsocketGateway时，经常会遇到处理输入数据验证的情况。为了确保接收到的数据符合预期的格式和规则，我们可以使用ValidationPipe进行数据验证。然而，有时候当验证失败时，ValidationPipe会返回一个内部服务器错误，而不是返回具体的验证错误信息。本文将介绍如何解决这个问题，并提供相应的案例代码。

typescript
import { WebSocketGateway, WebSocketServer, OnGatewayConnection, OnGatewayDisconnect } from '@nestjs/websockets';
import { Server } from 'socket.io';
import { ValidationPipe } from '@nestjs/common';
@WebSocketGateway()
export class MyGateway implements OnGatewayConnection, OnGatewayDisconnect {
  constructor() {
    this.server = io(server);
    this.server.use(new ValidationPipe());
  }
  
  // ...
}

typescript
@WebSocketGateway()
export class MyGateway implements OnGatewayConnection, OnGatewayDisconnect {
  // ...
  
  @SubscribeMessage('message')
  onMessage(client: Socket, message: any) {
    // 使用ValidationPipe验证接收到的消息
    const validatedMessage = ValidationPipe.transform(message, {
      metatype: MessageDto, // 验证规则定义在MessageDto类中
    });
    // 处理验证后的消息
    // ...
  }
}

typescript
import { ExceptionFilter, Catch, ArgumentsHost } from '@nestjs/common';
import { ValidationError } from 'class-validator';
import { Socket } from 'socket.io';
@Catch(ValidationError)
export class ValidationExceptionFilter implements ExceptionFilter {
  catch(exception: ValidationError, host: ArgumentsHost) {
    const client = host.switchToWs().getClient();
    const errors = exception.map((error) => Object.values(error.constraints));
    client.emit('validationError', errors);
  }
}

typescript
import { ValidationExceptionFilter } from './validation-exception.filter';
async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  
  // 注册全局过滤器
  app.useGlobalFilters(new ValidationExceptionFilter());
  
  // ...
  
  await app.listen(3000);
}
bootstrap();