NestJs - 使用自定义过滤器和 @Catch(MongoError) 捕获 MongoDB 错误 [英] NestJs - Catching MongoDB errors with a custom filter and @Catch(MongoError)

问题描述

我正在使用 NestJS 通过 MongoDB 创建自定义 API.我有以下设置:

I'm using NestJS to create a custom API with MongoDB. I've got the following setup:

  // users.controller.ts

  @Post('sign-up')
  @UseFilters(MongoExceptionFilter)
  async signUp(@Body() createUserDto: CreateUserDto): Promise<any> {
    return await this.userService.signUp(createUserDto).catch(error => {
      throw new BadRequestException(error);
    });
  }

  // user.service.ts

  async signUp(createUserDto: CreateUserDto): Promise<User> {
  const createUser = new this.userModel(createUserDto);
    return await createUser.save();
  }

  // mongo-exception.filter.ts

  import { ArgumentsHost,Catch, ConflictException, ExceptionFilter } from '@nestjs/common';
  import { MongoError } from 'mongodb';

  @Catch(MongoError)
  export class MongoExceptionFilter implements ExceptionFilter {
    catch(exception: MongoError, host: ArgumentsHost) {
      console.log('>>>>>>>>>>>>>>>>>>>> exception: ', exception);
    }
  }

  // package.json
  "dependencies": {
    "@nestjs/common": "^5.4.0",
    "@nestjs/core": "^5.4.0",
    "@nestjs/jwt": "^0.2.1",
    "@nestjs/mongoose": "^5.2.2",
    "@nestjs/passport": "^5.1.0",
    "@nestjs/typeorm": "^5.2.2",
    "fancy-log": "^1.3.3",
    "mongoose": "^5.4.7",
    "nestjs-config": "^1.3.0",
    "passport": "^0.4.0",
    "passport-http-bearer": "^1.0.1",
    "passport-jwt": "^4.0.0",
    "reflect-metadata": "^0.1.12",
    "rimraf": "^2.6.2",
    "rxjs": "^6.2.2",
    "typeorm": "^0.2.12",
    "typescript": "^3.0.1",
    "util": "^0.11.1"
  },

现在，每当我对/sign-up 路由进行 POST 调用时，应该在 user.service.ts 中调用 save().这一切都有效.接下来，当我再次发布/sign-up 路由时，它应该会触发 MongoDB 错误，因为具有相同电子邮件地址的用户已经存在(电子邮件地址是唯一的，因此是重复的键).当我在 .catch(err => ...); 中记录错误时，我看到错误被抛出，但问题是自定义 MongoExceptionFilter.我不会触发 MongoError.当我将 @Catch() 留空时，它会触发但无法处理异常.

Now whenever I do a POST call to the /sign-up route, save() should be called in the user.service.ts. This all works. Next when I POST the /sign-up route another time it should trigger a MongoDB error since the user with the same email address is already (email address is unique and thus duplicate keys). I see the error is thrown when I just log the error in the .catch(err => ...);, but the problem is the custom MongoExceptionFilter. I won't trigger on the MongoError. When I leave the @Catch() blank it does trigger but can't process the exception.

我做错了什么?由于我看到了这篇帖子并将其用作基础，我可以'似乎让它发挥作用.是 Mongoose 还是 NestJS 的更新，为什么这不再起作用了?

What am I doing wrong? Since I saw this post and used this as a foundation I can't seem to get it to work. Is it an update of Mongoose or NestJS why this isn't working anymore?

推荐答案

这是因为你把所有的错误都转换成BadRequestExceptions，这样你的MongoExceptionFilter 就不用负责了；它检查 instanceof MongoError，它为 BadRequestException 返回 false:

This is because you convert all errors to BadRequestExceptions so that your MongoExceptionFilter will not be responsible; it checks instanceof MongoError which returns false for a BadRequestException:

return await this.userService.signUp(createUserDto).catch(error => {
      throw new BadRequestException(error);
    });

这发生在异常过滤器运行之前；他们总是最后运行.

This happens before the exception filters are run; they always run last.

从控制器中删除 .catch().如果您真的想将所有其他异常转换为 BadRequestExceptions (400)，那么您可以编写第二个异常过滤器，处理所有未被 MongoExceptionFilter 处理的异常:

Remove .catch() from your controller. If you really want to transform all other exceptions to BadRequestExceptions (400), then you can write a second exception filter, that processes all exceptions not handled by the MongoExceptionFilter:

@Catch()
export class BadRequestFilter implements ExceptionFilter {
  catch(exception: Error, host: ArgumentsHost) {
    const response = host.switchToHttp().getResponse();
    response.status(400).json({message: exception.message});
  }
}

和

@Catch(MongoError)
export class MongoFilter implements ExceptionFilter {
  catch(exception: MongoError, host: ArgumentsHost) {
    const response = host.switchToHttp().getResponse();
    if (exception.code === 11000) {
      response.status(400).json({ message: 'User already exists.' });
    } else {
      response.status(500).json({ message: 'Internal error.' });
    }
  }
}

然后将两者都添加到您的控制器中(顺序很重要！):

Then add both to your controller (order is important!):

@UseFilters(BadRequestFilter, MongoFilter)
async signUp(@Body() createUserDto: CreateUserDto): Promise<any> {

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