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

Question

我正在尝试在 NestJS 中向我的 WebSocketGateway 添加一些验证。代码如下：

// MessageDTO

import { IsNotEmpty, MinLength } from 'class-validator';

export class MessageDTO {
  @IsNotEmpty()
  username: string;

  @IsNotEmpty()
  @MinLength(10)
  text: string;
}

// Gateway

import { ValidationPipe, UsePipes } from '@nestjs/common';
import { MessageBody, SubscribeMessage, WebSocketGateway, WsResponse } from '@nestjs/websockets';
import { MessageService } from './message/message.service';
import { MessageDTO } from './message/message.dto';
import { Message } from './message/message.entity';

@WebSocketGateway()
export class AppGateway {
  constructor(private readonly messageService: MessageService) {}

  @UsePipes(new ValidationPipe())
  @SubscribeMessage('message')
  async handleMessage(@MessageBody() dto: MessageDTO): Promise<WsResponse<Message>> {
    const message = await this.messageService.saveMessage(dto);
    return { event: 'message', data: message };
  }
}

现在，当我尝试发送不符合验证规则的消息时，它会出错，但客户端始终会收到{ status: 'error', message: 'Internal server error'}。此外，Nest 将错误记录到控制台（我认为这不应该发生......？）：

thing_api | Error: Bad Request Exception
thing_api |     at ValidationPipe.exceptionFactory (/usr/src/app/node_modules/@nestjs/common/pipes/validation.pipe.js:78:20)
thing_api |     at ValidationPipe.transform (/usr/src/app/node_modules/@nestjs/common/pipes/validation.pipe.js:50:24)
thing_api |     at processTicksAndRejections (internal/process/task_queues.js:89:5)
thing_api |     at async resolveParamValue (/usr/src/app/node_modules/@nestjs/websockets/context/ws-context-creator.js:104:31)
thing_api |     at async Promise.all (index 0)
thing_api |     at async pipesFn (/usr/src/app/node_modules/@nestjs/websockets/context/ws-context-creator.js:106:13)
thing_api |     at async /usr/src/app/node_modules/@nestjs/websockets/context/ws-context-creator.js:41:17
thing_api |     at async AppGateway.<anonymous> (/usr/src/app/node_modules/@nestjs/websockets/context/ws-proxy.js:11:32)
thing_api |     at async WebSocketsController.pickResult (/usr/src/app/node_modules/@nestjs/websockets/web-sockets-controller.js:85:24)

但是，如果我在常规控制器中使用相同的 DTO 和验证管道，它就像一个魅力 - 使用格式错误的有效负载我会收到格式正确的错误消息。有人能指出我做错了什么吗？

Answer 1

BadRequestException 是HttpException 的子类。 Nest 的默认 exception handler for websockets 检查捕获的异常是否为 instanceof WsException，如果不是则返回未知异常。

要解决这个问题，您可以实现一个过滤器，捕获 BadRequestException 并将其转换为适当的 WsException，然后让 Nest 的异常过滤器从那里处理异常。

@Catch(BadRequestException)
export class BadRequestTransformationFilter extends BaseWsExceptionFilter {
  catch(exception: BadRequestException, host: ArgumentHost) {
    const properException = new WsException(exception.getResponse());
    super.catch(properException, host);
  }
}

Answer 2

我已经创建了我的 SocketValidation 管道

import { PipeTransform, Injectable, ArgumentMetadata, ValidationPipe } from '@nestjs/common';
import { validate } from 'class-validator';
import { plainToClass } from 'class-transformer';
import { WsException } from '@nestjs/websockets';

@Injectable()
export class SocketValidationPipe  implements PipeTransform<any> {

  constructor() {
    // super(options)
  }

  async transform(value: any, { metatype }: ArgumentMetadata) {
    if (!metatype || !this.toValidate(metatype)) {
      return value;
    }
    const object = plainToClass(metatype, JSON.parse(value));
    const errors = await validate(object);
    if (errors.length > 0) {
      throw new WsException('Wrong message!');//new BadRequestException('Validation failed');
    }
    return value;
  }

  private toValidate(metatype: Function): boolean {
    const types: Function[] = [String, Boolean, Number, Array, Object];
    return !types.includes(metatype);
  }
}

Answer 3

你可以重写the default websocket filter，捕获http异常和websocket异常。

import { ArgumentsHost, Catch, HttpException } from '@nestjs/common';
import { WsException } from '@nestjs/websockets';
import { Socket } from 'socket.io';

@Catch(WsException, HttpException)
export class WsExceptionFilter {
  public catch(exception: HttpException, host: ArgumentsHost) {
    const client = host.switchToWs().getClient();
    this.handleError(client, exception);
  }

  public handleError(client: Socket, exception: HttpException | WsException) {
    if (exception instanceof HttpException) {
      // handle http exception
    } else {
      // handle websocket exception
    }
  }
}

然后在你的网关中使用它

@UseFilters(WsExceptionFilter)
@WebSocketGateway()
export class WorkspacesGateway {}

Answer 4

ValidationPipe 获得了exceptionFactory 选项，因此您可以将自定义工厂传递给它，例如：

@UsePipes(new ValidationPipe({
    exceptionFactory(validationErrors = []) {
        if (this.isDetailedOutputDisabled) {
            return new WsException('Bad request');
        }
        const errors = this.flattenValidationErrors(validationErrors);

        return new WsException(errors);
    }
}))

或者扩展内置的ValidationPipe

import {Injectable, ValidationPipe} from '@nestjs/common';
import {WsException} from "@nestjs/websockets";

@Injectable()
export class WSValidationPipe extends ValidationPipe{

  createExceptionFactory() {
    return (validationErrors = []) => {
      if (this.isDetailedOutputDisabled) {
        return new WsException('Bad request');
      }
      const errors = this.flattenValidationErrors(validationErrors);

      return new WsException(errors);
    };
  }

}