Nestjs: Unable to connect mongo asynchronously

Question

I am unable to connect to mongodb asynchronously. Please let me know what am I doing wrong.

MongoConfig file:

import { MongooseModuleOptions } from '@nestjs/mongoose';

export default (): { mongoConfig: MongooseModuleOptions } => ({
  mongoConfig: {
    uri: process.env.DB_URI,
    connectionName: 'learn-nest',
    useCreateIndex: true,
    useUnifiedTopology: true,
    useFindAndModify: false,
    useNewUrlParser: true,
  },
});

Here is the code written inside of App Module

import { Module } from '@nestjs/common';
import { AppController } from './app.controller';
import { AppService } from './app.service';
import { MongooseModule } from '@nestjs/mongoose';
import { ConfigModule, ConfigService } from '@nestjs/config';

@Module({
  imports: [
    ConfigModule.forRoot({
      envFilePath: ['.env'],
      isGlobal: true,
      cache: true,
    }),
    MongooseModule.forRootAsync({
      useFactory: (configService: ConfigService): any => {
        configService.get('mongoConfig');
      },
      inject: [ConfigService],
    }),
  ],
  controllers: [AppController],
  providers: [AppService],
})
export class AppModule {}

This is the error that it throws:

"Cannot destructure property 'retryAttempts' of 'mongooseModuleOptions' as it is undefined"

I do not understand why it's throwing this error because, 'retryAttempts' is an optional property in MongooseModuleOptions interface.

MongooseModuleInterface

export interface MongooseModuleOptions extends ConnectOptions, Record<string, any> {
    uri?: string;
    retryAttempts?: number;
    retryDelay?: number;
    connectionName?: string;
    connectionFactory?: (connection: any, name: string) => any;
}

score 7 · Accepted Answer · answered May 24 '21 at 11:33

If your'e going for async MongoDB configuration, go for a separate config class. I'll explain how:

Make a new service for resolving MongoDB config.

mongodb.config.service.ts

import { Injectable } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import {
  MongooseModuleOptions,
  MongooseOptionsFactory,
} from '@nestjs/mongoose';

@Injectable()
export class MongodbConfigService implements MongooseOptionsFactory {

  constructor(private readonly configService: ConfigService) {}

  //You can retrun promise as well
  public createMongooseOptions(): MongooseModuleOptions {
    return {
      //MONGODB_URL is in .env file
      //MONGO_REPL_SET is in .env file
      //MONGO_AUTH_SOURCE is in .env file
      uri: this.configService.get<string>('MONGODB_URL'),
      useNewUrlParser: true,
      useFindAndModify: false,
      useCreateIndex: true,
      useUnifiedTopology: true,
      replicaSet: this.configService.get<string>('MONGO_REPL_SET'),
      authSource:  this.configService.get<string>('MONGO_AUTH_SOURCE'),
    };
  }
}

Mongoose module import :

//...
MongooseModule.forRootAsync({
      imports: [ConfigModule],
      useClass: MongodbConfigService,
    }),
//...

If you want to configure MongoDB as config namespace :

Make a file for holding the config: mongodb.config.ts

import { registerAs } from '@nestjs/config';

// @returns MongooseModuleOptions
export default registerAs('mongo_db', () => ({
      //MONGODB_URL is in .env file
      //MONGO_REPL_SET is in .env file
      //MONGO_AUTH_SOURCE is in .env file
      uri: process.env.MONGODB_URL,
      useNewUrlParser: true,
      useFindAndModify: false,
      useCreateIndex: true,
      useUnifiedTopology: true,
      replicaSet: process.env.MONGO_REPL_SET,
      authSource: process.env.MONGO_AUTH_SOURCE,
}));

Now in the Config Module import:

import mongoDbConfig from '<path>/mongodb.config';
//...
ConfigModule.forRoot({
      envFilePath: ['.env'],
      isGlobal: true,
      cache: true,
      load:[mongoDbConfig]
    }),
//...

Mongoose module import :

//...
MongooseModule.forRootAsync({
    useFactory:(configService:ConfigService)=>{
       return this.configService.get<MongooseModuleOptions>('mongo_db')
       },
    inject: [ConfigService],
    }),
//...

Both of the approaches should work.

BTW: Replica set and auth source was copied from my config. ignore it if you do not have replica setup.

Thank you so much for this great explanation. Now it's clear to me how it works. — Sachin Yadav, May 25 '21 at 09:20
Any idea how to configure autoEncryption? https://mongoosejs.com/docs/field-level-encryption.html — Forkmohit, Aug 18 '23 at 12:11

score 0 · Answer 2 · answered May 23 '21 at 18:21

Your useFactory doesn't return anything, so there's no options for the MongooseModule to make use of. It would be like doing something like this

function getConfig(configService) {
  config.get('CONFIG_KEY');
}

const config = getConfig(configServce);
console.log(config) // undefined

The factory function doesn't return a value, so it's undefined. You can add return configServicce.get('mongoConfig') and it should work as expected. Or you can make the anonymous arrow function return an object by using () => ({}). The () around the {} are very important for returning an object inline, otherwise JS thinks it's a function body.

Thank you for you attention, Jay. I tried returning mongoConfig, but it still throws the same error. — Sachin Yadav, May 24 '21 at 04:25

score 0 · Answer 3 · answered Apr 29 '22 at 21:29

MongooseModule.forRootAsync({
  imports: [ConfigModule],
  useFactory: async (configService: ConfigService) => ({
    uri: configService.get<string>('MONGODB_URI'),
  }),
  inject: [ConfigService],
});

Just correct Mongoose dynamic import code to this and replace your MONGO_URI key.

Nestjs: Unable to connect mongo asynchronously

3 Answers3

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