Nestjs, typeorm中的entity中的互相引用问题

20230131-152600

使用nestjs时,用到typeorm,有互相引用关系的entity,老是报错,按照官方文档,最后总会报一个entity metadata not found的错误.

会出错的方式

试了好多次,发现需要这样写,假设有两个entity, 一个是UserEntity, 一个是CarEntity, 互相引用,按以下方法写,会报circular import errors

user.entity.ts

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import {
  Column,
  Entity,
  ManyToMany,
  PrimaryGeneratedColumn,
} from 'typeorm';
import { CarEntity } from './car.entity.ts'

@Entity({ name: 'users' })
export class UserEntity() {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  name: string;

  @ManyToMany(() => CarEntity, (car) => car.id)
  car: CarEntity
}

car.entity.ts

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import {
  Column,
  Entity,
  ManyToMany,
  PrimaryGeneratedColumn,
} from 'typeorm';
import { UserEntity } from './user.entity.ts'

@Entity({ name: 'users' })
export class CarEntity() {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  name: string;

  @ManyToMany(() => UserEntity, (user) => user.id)
  user: UserEntity
}

这种方式就会报找不到循环引用错误的错误: circular import errors,

全部按官方方式写,也会报错

user.entity.ts

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import {
  Column,
  Entity,
  ManyToMany,
  PrimaryGeneratedColumn,
} from 'typeorm';
import type { CarEntity } from './car.entity.ts'

@Entity({ name: 'users' })
export class UserEntity() {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  name: string;

  @ManyToMany('CarEntity', 'id')
  car: CarEntity
}

car.entity.ts

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import {
  Column,
  Entity,
  ManyToMany,
  PrimaryGeneratedColumn,
} from 'typeorm';
import type { UserEntity } from './user.entity.ts'

@Entity({ name: 'users' })
export class CarEntity() {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  name: string;

  @ManyToMany('UserEntity', 'id')
  user: UserEntity
}

这样的方式又会报entity metadata not found的错误.

正确的方式

正确的方式是,只需要一个文件按import type方式,另一个文件还是正常import

user.entity.ts

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import {
  Column,
  Entity,
  ManyToMany,
  PrimaryGeneratedColumn,
} from 'typeorm';
import { CarEntity } from './car.entity.ts'

@Entity({ name: 'users' })
export class UserEntity() {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  name: string;

  @ManyToMany(() => CarEntity, (car) => car.id)
  car: CarEntity
}

car.entity.ts

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import {
  Column,
  Entity,
  ManyToMany,
  PrimaryGeneratedColumn,
} from 'typeorm';
import type { UserEntity } from './user.entity.ts'

@Entity({ name: 'users' })
export class CarEntity() {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  name: string;

  @ManyToMany('UserEntity', 'id')
  user: UserEntity
}

这样就OK了.

tag: nestjs, typeorm, entity, metadata not found, circular import errors