“TypeError：无法使用graphql和mongodb读取未定义的属性'原型'”nestjs答案

【问题标题】："TypeError: Cannot read property 'prototype' of undefined" nestjs with graphql and mongodb“TypeError：无法使用graphql和mongodb读取未定义的属性'原型'”nestjs
【发布时间】：2022-02-04 23:03:13
【问题描述】：

我遇到了这个错误，我不确定如何解决它。当我尝试运行 getLesson() 函数时出现错误，我只是想通过公共 ID 获取课程。

错误和代码如下所示

{ “错误”：[ { "message": "无法读取未定义的属性 'prototype'", “地点”：[ { “线”：2， “列”：3 } ], “小路”： [ “课” ], “扩展”：{ “代码”：“INTERNAL_SERVER_ERROR”， “例外”： { “堆栈跟踪”： [ “TypeError：无法读取未定义的属性‘原型’”， "在 FindCursor.cursor.toArray (C:\Users\LENOVO\Projects\practice\graphql-mongodb\src\entity-manager\MongoEntityManager.ts:704:37)"， "在 MongoEntityManager。(C:\Users\LENOVO\Projects\practice\graphql-mongodb\src\entity-manager\MongoEntityManager.ts:189:46)", " 在步骤 (C:\Users\LENOVO\Projects\practice\graphql-mongodb\node_modules\tslib\tslib.js:143:27)", " 在 Object.next (C:\Users\LENOVO\Projects\practice\graphql-mongodb\node_modules\tslib\tslib.js:124:57)", " 完成时 (C:\Users\LENOVO\Projects\practice\graphql-mongodb\node_modules\tslib\tslib.js:114:62)", “在 processTicksAndRejections (internal/process/task_queues.js:95:5)” ] } } } ], “数据”：空 }

lesson.service.ts

import { Injectable } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Lesson } from './lesson.entity';
import { Repository } from 'typeorm';
import { v4 as uuid } from 'uuid';

@Injectable()
export class LessonService {
  constructor(
    @InjectRepository(Lesson)
    private lessonRepository: Repository<Lesson>,
  ) {}

  async getLesson(id: string): Promise<Lesson> {
    return this.lessonRepository.findOne({ id });
  }
}

lesson.resolver.ts

import { Resolver, Query, Mutation, Args } from '@nestjs/graphql';
import { LessonService } from './lesson.service';
import { LessonType } from './lesson.type';

@Resolver((of) => LessonType)
export class LessonResolver {
  constructor(private lessonService: LessonService) {}

  //queries are used to retrieve data and mutations are user to create or modify data
  @Query((returns) => LessonType)
  lesson(@Args('id') id: string) {
    return this.lessonService.getLesson(id);
  } }

课程类型.ts

import { ObjectType, Field, ID } from '@nestjs/graphql';

@ObjectType('Lesson')
export class LessonType {
  @Field((type) => ID)
  id: string;

  @Field()
  name: string;

  @Field()
  startDate: string;

  @Field()
  endDate: string;
}

lesson.entity.ts

import { Entity, PrimaryColumn, Column, ObjectIdColumn } from 'typeorm';

@Entity()
export class Lesson {
  @ObjectIdColumn()
  _id: string;

  @PrimaryColumn()
  id: string;

  @Column()
  name: string;

  @Column()
  startDate: string;

  @Column()
  endDate: string;
}

【问题讨论】：

标签： node.js typescript mongodb graphql nestjs

【解决方案1】：

mongodb v4有问题需要降级到v3

yarn add mongodb@3
npm install mongodb@3

我使用的是 3.7.1 版本，它运行良好

这里：TypeORM error with MongoDB: .find() does not work, error: TypeError: Cannot read property 'prototype' of undefined

【讨论】：