I want to inject a mongo db model in NestJS Service. The model is present in the root module only.

import { Injectable } from '@nestjs/mon';
import { InjectModel } from '@nestjs/mongoose';
import { Model } from 'mongoose';
import { IFolderModel } from './interfaces/folder.interface';

@Injectable()
export class FolderService {
    constructor(@InjectModel('IFolder') private folderModel: Model<IFolderModel>) {

    }

    async create(folderInstance: IFolderModel): Promise<IFolderModel> {
       const folderModelToBeSaved = new this.folderModel(folderInstance);
       return await folderModelToBeSaved.save();
    }

    async findAll(): Promise<IFolderModel[]> {
       return await this.folderModel.find().exec();
    }
} 

I am getting following error while starting application using npm run start

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

Contents of AppModule

 let mongodb = env.mongodb;
 let url = `mongodb://${mongodb.user}:${mongodb.pwd}@${mongodb.host}:${mongodb.port}/${mongodb.dbName}`;

 @Module({
    imports: [MongooseModule.forRoot(url)],
    controllers: [AppController, FolderController],
    providers: [AppService, FolderService],
 })
 export class AppModule { }

I want to inject a mongo db model in NestJS Service. The model is present in the root module only.

import { Injectable } from '@nestjs/mon';
import { InjectModel } from '@nestjs/mongoose';
import { Model } from 'mongoose';
import { IFolderModel } from './interfaces/folder.interface';

@Injectable()
export class FolderService {
    constructor(@InjectModel('IFolder') private folderModel: Model<IFolderModel>) {

    }

    async create(folderInstance: IFolderModel): Promise<IFolderModel> {
       const folderModelToBeSaved = new this.folderModel(folderInstance);
       return await folderModelToBeSaved.save();
    }

    async findAll(): Promise<IFolderModel[]> {
       return await this.folderModel.find().exec();
    }
} 

I am getting following error while starting application using npm run start

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

Contents of AppModule

 let mongodb = env.mongodb;
 let url = `mongodb://${mongodb.user}:${mongodb.pwd}@${mongodb.host}:${mongodb.port}/${mongodb.dbName}`;

 @Module({
    imports: [MongooseModule.forRoot(url)],
    controllers: [AppController, FolderController],
    providers: [AppService, FolderService],
 })
 export class AppModule { }

• javascript
• node.js
• typescript
• mongoose
• nestjs

2 Answers 2

You have to additionally import your schemas with MongooseModule.forFeature. Usually, you would set up the database connection in the root module and then import the schemas in dedicated feature modules. This is why the imports are separate.

MongooseModule.forFeature([{ name: 'Folder', schema: FolderSchema }])

For further information, see the mongo docs.

This should be in the imports array of your module

@Module({
  imports: [
    MongooseModule.forFeature([{ name: 'FolderName', schema: FolderSchema }]),
  ],
})