nest-mongodb

Description

This is a MongoDB module for NestJS, making it easy to inject the MongoDB driver into your project. It's modeled after the official Mongoose module, allowing for asynchronous configuration and such.

Installation

In your existing NestJS-based project:

$ npm install nest-mongodb mongodb

Usage

Overall, it works very similarly to the Mongoose module described in the NestJS documentation, though without any notion of models. You may want to refer to those docs as well -- and maybe the dependency injection docs too if you're still trying to wrap your head around the NestJS implementation of it.

Simple example

In the simplest case, you can explicitly specify the database URI, name, and options you'd normally provide to your MongoClient using MongoModule.forRoot():

import { Module } from '@nestjs/common'
import { MongoModule } from 'nest-mongodb'

@Module({
    imports: [MongoModule.forRoot('mongodb://localhost', 'BestAppEver')]
})
export class CatsModule {}

To inject the Mongo Db object:

import * as mongo from 'mongodb'
import { Injectable } from '@nestjs/common'
import { InjectDb } from 'nest-mongodb'
import { Cat } from './interfaces/cat'

@Injectable()
export class CatsRepository {
    private readonly collection: mongo.Collection

    constructor(@InjectDb() private readonly db: mongo.Db) {
        this.collection = this.db.collection('cats')
    }

    async create(cat: Cat) {
        const result = await this.collection.insertOne(cat)

        if (result.insertedCount !== 1 || result.ops.length < 1) {
            throw new Error('Insert failed!')
        }

        return result.ops[0]
    }
}

To inject a collection object:

import { Module } from '@nestjs/common'
import { MongoModule } from 'nest-mongodb'
import { CatsController } from './cats.controller'
import { CatsService } from './cats.service'

@Module({
  imports: [MongoModule.forFeature(['cats'])],
  controllers: [CatsController],
  providers: [CatsService],
})
export class CatsModule {}

import * as mongo from 'mongodb'
import { Injectable } from '@nestjs/common'
import { InjectCollection } from 'nest-mongodb'
import { Cat } from './interfaces/cat'

@Injectable()
export class CatsRepository {
    constructor(@InjectCollection('cats') private readonly catsCollection: mongo.Collection) {}

    async create(cat: Cat) {
        const result = await this.catsCollection.insertOne(cat)

        if (result.insertedCount !== 1 || result.ops.length < 1) {
            throw new Error('Insert failed!')
        }

        return result.ops[0]
    }
}

Asynchronous configuration

If you want to pass in Mongo configuration options from a ConfigService or other provider, you'll need to perform the Mongo module configuration asynchronously, using MongoModule.forRootAsync(). There are several different ways of doing this.

Use a factory function

The first is to specify a factory function that populates the options:

import { Module } from '@nestjs/common'
import { MongoModule } from 'nest-mongodb'
import { ConfigService } from '../config/config.service'

@Module({
    imports: [MongoModule.forRootAsync({
        imports: [ConfigModule],
        useFactory: (config: ConfigService) => {
            uri: config.mongoUri,
            dbName: config.mongoDatabase
        },
        inject: [ConfigService]
    })]
})
export class CatsModule {}

Use a class

Alternatively, you can write a class that implements the MongoOptionsFactory interface and use that to create the options:

import { Module } from '@nestjs/common'
import { MongoModule, MongoOptionsFactory, MongoModuleOptions } from 'nest-mongodb'

@Injectable()
export class MongoConfigService implements MongoOptionsFactory {
    private readonly uri = 'mongodb://localhost'
    private readonly dbName = 'BestAppEver'

    createMongoOptions(): MongoModuleOptions {
        return {
            uri: this.uri,
            dbName: this.dbName
        }
    }
}

@Module({
    imports: [MongoModule.forRootAsync({
        useClass: MongoConfigService
    })]
})
export class CatsModule {}

Just be aware that the useClass option will instantiate your class inside the MongoModule, which may not be what you want.

Use existing

If you wish to instead import your MongoConfigService class from a different module, the useExisting option will allow you to do that.

import { Module } from '@nestjs/common'
import { MongoModule } from 'nest-mongodb'
import { ConfigModule, ConfigService } from '../config/config.service'

@Module({
    imports: [MongoModule.forRootAsync({
        imports: [ConfigModule]
        useExisting: ConfigService
    })]
})
export class CatsModule {}

In this example, we're assuming that ConfigService implements the MongoOptionsFactory interface and can be found in the ConfigModule.