Nest.js学习之路(17)-TypeORM(4)设定一对多/

关于TypeORM设定一对多/多对一参考官网教学

假设新增用户entitiy，使得一个平台有多个使用者，代码如下:

import {Entity, PrimaryGeneratedColumn, Column, ManyToOne, RelationId} from 'typeorm';
import { Platform } from './Platform';

@Entity()
export class User {
    @PrimaryGeneratedColumn()
    id: number;

    @Column()
    name: string;

    @Column()
    age: number;

    @ManyToOne( type => Platform, platform => platform.users, {
        onDelete: 'NO ACTION',
    })
    plat: Platform;

    @RelationId((user: User) => user.plat)
    platId: number;
}

在platform entity上，新增users属性并设定@OneToMany()

import {Column, Entity, PrimaryGeneratedColumn, OneToMany} from 'typeorm';
import { User } from './User';

@Entity() // 指定table name
export class Platform {
    // 每新增一个的時候id+1
    @PrimaryGeneratedColumn()
    id: number;

    // @Column为对应的数据库列，或是传入Column Options物件
    @Column()
    platformname: string;

    // 传入Column Options物件设定mapping的列位属性
    @Column({
      type: 'varchar',
      length: 50,
      default: '123',
    })
    title: string;

    @Column()
     url: string;

    @Column({
        default: true, // 给预设值
    })
    isActive: boolean;

    @OneToMany( type => User, user => user.plat ) // type指定User， 第二個参数是function预设传入第一个参数的type，这边需要设定inverse屬性，user entity里的dep屬性，这个属性不会存到数据库
    users: [];
}

在feature文件夹下新建user文件夹，然后在user文件夹下分别新建user.controller.ts,user.module.ts,user.service.ts,userDTO.ts四个文件,

userDTO.ts文件代码如下：

import { IsString, MaxLength, IsNumber } from 'class-validator';

export class UserDTO {
    @IsString()
    @MaxLength(100)
    name: string;

    @IsNumber()
    age: number;
}

user.service.ts文件内容如下：

import { Injectable } from '@nestjs/common';
import { User } from 'shared/entity/User';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import { UserDTO } from './userDTO';

@Injectable()
export class UserService {
    constructor(
        @InjectRepository(User)
        private readonly userRepo: Repository<User>,
    ) {}

    async addUser(userDTO: UserDTO) {
        const user = new UserDTO();
        user.name = userDTO.name;
        user.age = userDTO.age;
        return await this.userRepo.save(user);
    }

    async getUserById(id) {
        return await this.userRepo.findOne(id);
    }
}

对应的user.controller.ts代码如下：

import { Controller, Post, Body } from '@nestjs/common';
import { UserService } from './user.service';
import { UserDTO } from './userDTO';

@Controller('user')
export class UserController {
    constructor(
        private readonly userService: UserService,
    ) {}

    @Post()
    addUser(@Body() userDTO: UserDTO) {
        return this.userService.addUser(userDTO);
    }
}

最后在user.module.ts写入如下代码:

import { Module } from '@nestjs/common';
import { TypeOrmModule } from '@nestjs/typeorm';
import { User } from 'shared/entity/User';
import { UserService } from './user.service';
import { UserController } from './user.controller';

@Module({
  imports: [TypeOrmModule.forFeature([User])],
  providers: [UserService],
  controllers: [UserController],
})
export class UserModule {}

然后我们用postman来新增一个用户

2018111308.png

加入platId于userDTO，新增User时指定所属平台

export class UserDTO {
    
    ...
    @IsNumber()
    platId: number;
}

在user.service.ts，修改新增与修改逻辑，

import { Injectable } from '@nestjs/common';
import { User } from 'shared/entity/User';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import { UserDTO } from './userDTO';
import { Platform } from 'shared/entity/Platform';
import { PlatformService } from 'feature/platform/platform.service';

@Injectable()
export class UserService {
    constructor(
        @InjectRepository(User)
        private readonly userRepo: Repository<User>,
        private platformService: PlatformService,
    ) {}

    async addUser(userDTO: UserDTO) {
        const user = new UserDTO();
        user.name = userDTO.name;
        user.age = userDTO.age;
        // user.platId  = data.platId; 不能只指定id，必须传入platform对象save的时候才会储存关联资料
        user.plat = await this.platformService.getPlatformById(userDTO.platId);
        return await this.userRepo.save(user);
    }

    async getUsers(): Promise<User[]>{
        return await this.userRepo.find({relations: ['plat']}); // relations指定载入关联属性，是阵列，可能有多个导出属性
    }

    async getUserById(id) {
        return await this.userRepo.findOne(id, {relations: ['plat']});
        // relations指定载入关联属性，是阵列，可能有多个导览属性
        // return await this.userRepo.findOneOrFail(id); // 以id搜寻，没找到会丢出例外
    }

    async updateUser(id, data: UserDTO){
        const user = new User();
        user.name = data.name;
        user.age = data.age;
        user.plat = await this.platformService.getPlatformById(data.platId);
        return await this.userRepo.update(id, user); // 用data里的值更新到数据库
    }
}

使用postman测试

2018111401.png

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