NestJS - Use multiple MongoDB connections per module - node.js

Question

Is there a way to connect multiple MongoDB connections per module?
app.module.ts
#Module({
imports: [
MongooseModule.forRoot('mongodb://localhost/masterDB'),
UserModule,
],
controllers: [AppController],
providers: [AppService],
})
export class AppModule { }
Similarly, can we define another connection in another module which is a child of app.module?
child.module.ts
#Module({
imports: [
MongooseModule.forRoot('mongodb://localhost/childDB'),
MongooseModule.forFeature([{ name: 'child', schema: ChildSchema }]),
],
controllers: [ChildController],
providers: [ChildService],
})
export class ChildModule { }
Or any other way to access different databases at once.
Thanks in advance!

Answer 1

[SOLVED March 2021]
Here you'll find the solution:
https://www.learmoreseekmore.com/2020/04/nestjs-multiple-mongodb-databases.html
import { Module } from '#nestjs/common';
import { MongooseModule } from '#nestjs/mongoose';
import { studentSchema } from './schemas/myworld/student.schema';
import { animalSchema } from './schemas/wildlife/animal.schema';
#Module({
imports: [
MongooseModule.forFeature([
{
name: 'Student',
schema: studentSchema,
collection: 'Student',
},
],'myWorldDb'),
MongooseModule.forFeature([
{
name: 'Animals',
schema: animalSchema,
collection: 'Animals'
}
],'wildLifeDb'),
MongooseModule.forRoot(
'mongodb+srv://<userName>:<password>#cluster0-igk.mongodb.net/MyWorld?retryWrites=true&w=majority',
{
connectionName: 'myWorldDb'
}
),
MongooseModule.forRoot(
'mongodb+srv://<username>:<password>#cluster0-igk.mongodb.net/WildLife?retryWrites=true&w=majority',
{
connectionName: 'wildLifeDb'
}
)
],
controllers: [],
providers: [],
})
export class AppModule {}

Answer 2

You have to do it manually you have to use a providers file:
mongoose.providers.ts
import * as mongoose from 'mongoose';
export const mongooseProviders = [
{
provide: 'MASTER_CONNECTION',
useFactory: (): Promise<typeof mongoose> =>
// This mongoose.connect never working for multples DB connection
// mongoose.connect('mongodb://localhost/masterDB'),
// Following is working fine and tested by me
mongoose.createConnection('mongodb://localhost/masterDB'),
},
{
provide: 'CHILD_CONNECTION',
useFactory: (): Promise<typeof mongoose> =>
// This mongoose.connect never working for multples DB connection
// mongoose.connect('mongodb://localhost/masterDB'),
// Following is working fine and tested by me
mongoose.createConnection('mongodb://localhost/ChildDB'),
},
];
mongoose.module.ts
import { Module } from '#nestjs/common';
import { mongooseProviders } from './mongoose.providers';
#Module({
providers: [...mongooseProviders],
exports: [...mongooseProviders],
})
export class MongooseModule {}
model.providers.ts
import { Connection } from 'mongoose';
import { ChildSchema } from './schemas/child/child.schema';
import { MasterSchema } from './schemas/master/master.schema';
export const modelProviders = [
{
provide: 'CHILD_MODEL',
useFactory: (connection: Connection) => connection.model('Child', ChildSchema),
inject: ['CHILD_CONNECTION'],
},
{
provide: 'MASTER_MODEL',
useFactory: (connection: Connection) => connection.model('Master', MasterSchema),
inject: ['MASTER_CONNECTION'],
},
];
And on the constructor instead of using #InjectModel you use #Inject:
#Injectable
export Class ModelService {
constructor(#Inject('MASTER_MODEL') private masterModel: Model<Master>) {}
...
Note: in the module you provide the service you should import the MongooseModule and put as provider modelProviders.

Answer 3

Post above from RalphJS really helped, but it only was using one connection for everything. Had to change 1 thing in model.providers.ts:
instead of mongoose.connect
you have to use mongoose.createConnection
model.providers.ts
import * as mongoose from 'mongoose';
export const mongooseProviders = [
{
provide: 'MASTER_CONNECTION',
useFactory: async (): Promise<unknown> =>
await mongoose.createConnection('mongodb://localhost/masterDB'),
},
{
provide: 'CHILD_CONNECTION',
useFactory: async (): Promise<unknown> =>
await mongoose.createConnection('mongodb://localhost/childDB'),
},
];
https://mongoosejs.com/docs/connections.html#multiple_connections