如何使用NestJS处理猫鼬错误 [英] How to handle mongoose error with nestjs

问题描述

我从 https://docs.nestjs.com/techniques/mongodb

问题是当出现猫鼬验证错误时(例如，我有一个带有必填字段的架构，但未提供):

The issue is when there is a mongoose validation error (e.g i have a schema with a required field and it isn't provided):

来自games.service.ts:

From games.service.ts:

  async create(createGameDto: CreateGameDto): Promise<IGame> {
    const createdGame = new this.gameModel(createGameDto);
    return await createdGame.save();
  }

save()函数返回一个Promise.

The save() function returns a Promise.

现在我在game.controller.ts

Now i have this in the game.controller.ts

  @Post()
  async create(@Body() createGameDto: CreateGameDto) {
    this.gamesService.create(createGameDto);
  }

处理错误然后返回具有不同http状态(可能是json文本)的响应的最佳方法是什么? 您通常会抛出一个HttpException，但是从哪里来?如果我在promise中使用.catch()处理错误，我将无法做到这一点.

What is the best way to handle an error and then return a response with a different http status and maybe a json text? You would usually throw a HttpException but from where? I can't do that if i handle the errors using .catch() in the promise.

(刚开始使用nestjs框架)

(Just started using the nestjs framework)

推荐答案

首先，您忘记在控制器内的create方法中添加return.这是一个常见的，非常令人误解的错误，我犯了上千遍，花了我几个小时来调试.

First, you forgot to add return in your create method inside the controller. This is a common, very misleading mistake I made a thousand of times and took me hours to debug.

要捕获异常:

您可以尝试使用@Catch捕获MongoError.

You could try to catch MongoError using @Catch.

对于我的项目，我正在执行以下操作:

For my projects I'm doing the following:

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

@Catch(MongoError)
export class MongoExceptionFilter implements ExceptionFilter {
  catch(exception: MongoError, host: ArgumentsHost) {
    switch (exception.code) {
      case 11000:
        // duplicate exception
        // do whatever you want here, for instance send error to client
    }
  }
}

然后您可以在控制器中像这样使用它(甚至可以将其用作全局/类范围的过滤器):

You can then just use it like this in your controller (or even use it as a global / class scoped filter):

import { MongoExceptionFilter } from '<path>/mongo-exception.filter';

@Get()
@UseFilters(MongoExceptionFilter)
async findAll(): Promise<User[]> {
  return this.userService.findAll();
}

(在findAll()调用中，重复的异常在这里没有意义，但您明白了.)

(Duplicate exception doesn't make sense here in a findAll() call, but you get the idea).

此外，我强烈建议您使用类验证器，如下所述: https://docs.nestjs. com/pipes

Further, I would strongly advise to use class validators, as described here: https://docs.nestjs.com/pipes

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