NestJs：从多个数据库中查询多个实体答案

【问题标题】：NestJs: Query multiple entities from multiple databaseNestJs：从多个数据库中查询多个实体
【发布时间】：2021-09-23 02:12:48
【问题描述】：

我有 mysql_server_1.database1.users

还有mysql_server_2.database3.users_revenue

如何查询用户的行
如何从 users_revenue 查询行

首先，我已经设置了连接：

const mysql1__database1 = TypeOrmModule.forRootAsync({
  imports: [ConfigModule],
  // @ts-ignore
  useFactory: (configService: ConfigService) => ({
    type: configService.get("DASHBOARD_DB_TYPE"),
    host: configService.get("DASHBOARD_DB_HOST"),
    port: configService.get("DASHBOARD_DB_PORT"),
    username: configService.get("DASHBOARD_DB_USER"),
    password: configService.get("DASHBOARD_DB_PASSWORD"),
    database: configService.get("DASHBOARD_DB_NAME"),
    entities: [__dirname + '/**/*.entity{.ts,.js}'],
    // entities: [User],
    autoLoadEntities: true,
    synchronize: true,
  }),
  inject: [ConfigService],
});

const mysql2__database3 = TypeOrmModule.forRootAsync({
  imports: [ConfigModule],
  // @ts-ignore
  useFactory: (configService: ConfigService) => ({
    name: 'mysql2__database3',
    type: configService.get("DASHBOARD2_DB_TYPE"),
    host: configService.get("DASHBOARD2_DB_HOST"),
    port: configService.get("DASHBOARD2_DB_PORT"),
    username: configService.get("DASHBOARD2_DB_USER"),
    password: configService.get("DASHBOARD2_DB_PASSWORD"),
    database: configService.get("DASHBOARD2_DB_NAME"),
    entities: [__dirname + '/**/*.entity{.ts,.js}'],
    // entities: [User],
    autoLoadEntities: true,
    synchronize: true,
  }),
  inject: [ConfigService],
});

@Module({
  imports: [
    mysql1__database1,
    mysql2__database3,
    StatsModule,
  ],
  controllers: [AppController],
  providers: [AppService, StatsService],
})
export class AppModule {}

user.service.ts

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

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

  async findAll(): Promise<User[]> {
    return await this.usersRepository.find();
  }
}

然后这段代码返回一个空数组，而不是我的数据库中存在这么多行；

const items = await this.userService.findAll();

--- 更新 --- 我看了一下 typeorm 源代码： https://github.com/nestjs/typeorm/blob/8af34889fa7bf14d7dc5541beef1d5c2b50c2609/lib/common/typeorm.decorators.ts#L13

然后https://docs.nestjs.com/techniques/database#multiple-databases

此时，您已经使用自己的连接注册了 User 和 Album 实体。使用此设置，您必须告诉 TypeOrmModule.forFeature() 方法和 @InjectRepository() 装饰器应该使用哪个连接。如果不传递任何连接名称，则使用默认连接。

所以我认为它应该有效？

@InjectRepository(User, 'mysql2_database3')

@Module({
  imports: [
    TypeOrmModule.forFeature([User], "mysql2_database3"),
  ],
  providers: [UserService],
  controllers: [StatsController],
})
export class StatsModule {}

还是报错：

请确保索引 [0] 处的参数 mysql2_database3Connection 在 TypeOrmModule 上下文中可用。

【问题讨论】：

标签： service entity nestjs typeorm

【解决方案1】：

感谢不和谐的@jmc29，他的指导帮助了

解决办法是：

const mysql2__database3 = TypeOrmModule.forRootAsync({
  imports: [ConfigModule],
  // @ts-ignore
  useFactory: (configService: ConfigService) => ({
    name: 'mysql2__database3',
    type: configService.get("DASHBOARD2_DB_TYPE"),
    host: configService.get("DASHBOARD2_DB_HOST"),
    port: configService.get("DASHBOARD2_DB_PORT"),
    username: configService.get("DASHBOARD2_DB_USER"),
    password: configService.get("DASHBOARD2_DB_PASSWORD"),
    database: configService.get("DASHBOARD2_DB_NAME"),
    entities: [__dirname + '/**/*.entity{.ts,.js}'],
    autoLoadEntities: true,
    synchronize: true,
  }),
  inject: [ConfigService],
});

再添加一行：

const mysql2__database3 = TypeOrmModule.forRootAsync({

  name: 'mysql2__database3', // -----> Add this line, it's is required

  imports: [ConfigModule],
  // @ts-ignore
  useFactory: (configService: ConfigService) => ({
    name: 'mysql2__database3',
    type: configService.get("DASHBOARD2_DB_TYPE"),
    host: configService.get("DASHBOARD2_DB_HOST"),
    port: configService.get("DASHBOARD2_DB_PORT"),
    username: configService.get("DASHBOARD2_DB_USER"),
    password: configService.get("DASHBOARD2_DB_PASSWORD"),
    database: configService.get("DASHBOARD2_DB_NAME"),
    entities: [__dirname + '/**/*.entity{.ts,.js}'],
    autoLoadEntities: true,
    synchronize: true,
  }),
  inject: [ConfigService],
});

【讨论】：