[document] mongodb ”Multiple databases“ do not work

[GongT]

Is there an existing issue for this?

• [X] I have searched the existing issues

Current behavior

Nest can't resolve dependencies of the AppService (?). Please make sure that the argument testModel at index [0] is available in the AppModule context.

Minimum reproduction code

https://github.com/GongT/issues/tree/nest-mongodb-multiple

Steps to reproduce

1. run a mongodb (I use docker: docker run -it --rm --name mongodb -p 27017:27017 mongo)
2. npm install
3. npm run start

Expected behavior

It should work

Package

• [ ] I don't know. Or some 3rd-party package
• [ ] @nestjs/common
• [ ] @nestjs/core
• [ ] @nestjs/microservices
• [ ] @nestjs/platform-express
• [ ] @nestjs/platform-fastify
• [ ] @nestjs/platform-socket.io
• [ ] @nestjs/platform-ws
• [ ] @nestjs/testing
• [ ] @nestjs/websockets
• [X] Other (see below)

Other package

No response

NestJS version

8.4.7

Packages versions

[System Information]
OS Version     : Linux 5.18
NodeJS Version : v18.3.0
PNPM Version    : 7.2.1 

[Nest CLI]
Nest CLI Version : 8.2.8 

[Nest Platform Information]
platform-express version : 8.4.7
schematics version       : 8.0.11
mongoose version         : 9.1.1
testing version          : 8.4.7
common version           : 8.4.7
core version             : 8.4.7
cli version              : 8.2.8

Node.js version

18.3.0

In which operating systems have you tested?

• [ ] macOS
• [ ] Windows
• [X] Linux

Other

I'm following the document (here)

https://github.com/GongT/issues/blob/nest-mongodb-multiple/src/app.module.ts#L7-L20

[GongT]

I think this is a bug, not only in document. see this

[Tony133]

Hi @GongT, to do the multi-connection you have to do this:

@Module({
  imports: [
    MongooseModule.forRoot('mongodb://localhost:27017/test1', {
      connectionName: 'mongodb1',
    }),
    MongooseModule.forRoot('mongodb://localhost:27018/test2', {
      connectionName: 'mongodb2',
    }),
  ],
  controllers: [AppController],
  providers: [AppService],
})
export class AppModule {}

However, for this type of question use the discord support channel.

The NestJS Core team uses GitHub to track bug reports, feature requests, and regressions.

[GongT]

please see my repo, this is a BUG, not a question.

I followed document step by step, and got an error.

After digging into source code, I found this may not because missing step in document, but a bug in nest's code.

[Tony133]

Hi @GongT, i saw your repo, there are implementation errors. I write you the solution below with the files to modify to use the multi-connection with mongoose:

app.module.ts:

import { Module } from '@nestjs/common';
import { AppController } from './app.controller';
import { AppService } from './app.service';
import { MongooseModule } from '@nestjs/mongoose';
import { test1Schema, test2Schema } from './app.model';

@Module({
  imports: [
    MongooseModule.forRoot('mongodb://localhost:27017/test1', {
      connectionName: 'mongodb1',
    }),
    MongooseModule.forRoot('mongodb://localhost:27018/test2', {
      connectionName: 'mongodb2',
    }),
    MongooseModule.forFeature(
      [{ name: 'collection1', schema: test1Schema }],
      'mongodb1',
    ),
    MongooseModule.forFeature(
      [{ name: 'collection2', schema: test2Schema }],
      'mongodb2',
    ),
  ],
  controllers: [AppController],
  providers: [AppService],
})
export class AppModule {}

app.service.ts:

import { Injectable } from '@nestjs/common';
import { InjectModel } from '@nestjs/mongoose';
import { Model } from 'mongoose';
import { DBTest, DBTest2 } from './app.model';

@Injectable()
export class AppService {
  constructor(
    @InjectModel('collection1', 'mongodb1')
    private mongodb1: Model<DBTest>,
    @InjectModel('collection2', 'mongodb2')
    private mongodb2: Model<DBTest2>,
  ) {}

  async getData1() {
    return await this.mongodb1.find().exec();
  }

  async getData2() {
    return await this.mongodb2.find().exec();
  }

  getHello(): string {
    return 'Hello World!';
  }
}

app.model.ts:

import { Prop, Schema, SchemaFactory } from '@nestjs/mongoose';

@Schema({ collection: 'collection1', timestamps: true })
export class DBTest {
  @Prop({ required: true })
  field: string;
}

export const test1Schema = SchemaFactory.createForClass(DBTest);

@Schema({ collection: 'collection2', timestamps: true })
export class DBTest2 {
  @Prop({ required: true })
  field: string;
}

export const test2Schema = SchemaFactory.createForClass(DBTest2);

app.controller.ts:

import { Controller, Get } from '@nestjs/common';
import { AppService } from './app.service';

@Controller()
export class AppController {
  constructor(private readonly appService: AppService) {}

  @Get()
  getHello(): string {
    return this.appService.getHello();
  }

  @Get('data1')
  getData() {
    return this.appService.getData1();
  }

  @Get('data2')
  getData2() {
    return this.appService.getData2();
  }
}

if you need it I also write the docker-compose.

P.s.: In the app.model the collections are better separated into two files, at least I usually do it like this, the choice is yours.

[GongT]

Great reply, thanks!

It's missing document about second argument of InjectModel.

Only one line mention this: here. I can't understand it without your reply above.

[Tony133]

Let's say something can be improved in the documentation or in an example, however if you want to contribute to the documentation feel free to do so and opensource!

[Tony133]

This issue we can close, it has been corrected through this PR: https://github.com/nestjs/docs.nestjs.com/pull/2434