Mongoose and multiple database in single node.js project

According to the fine manual, createConnection() can be used to connect to multiple databases.

However, you need to create separate models for each connection/database:

var conn      = mongoose.createConnection('mongodb://localhost/testA');
var conn2     = mongoose.createConnection('mongodb://localhost/testB');

// stored in 'testA' database
var ModelA    = conn.model('Model', new mongoose.Schema({
  title : { type : String, default : 'model in testA database' }
}));

// stored in 'testB' database
var ModelB    = conn2.model('Model', new mongoose.Schema({
  title : { type : String, default : 'model in testB database' }
}));

I'm pretty sure that you can share the schema between them, but you have to check to make sure.

Pretty late but this might help someone. The current answers assumes you are using the same file for your connections and models.

In real life, there is a high chance that you are splitting your models into different files. You can use something like this in your main file:

mongoose.connect('mongodb://localhost/default');

const db = mongoose.connection;

db.on('error', console.error.bind(console, 'connection error:'));
db.once('open', () => {
  console.log('connected');
});

which is just how it is described in the docs. And then in your model files, do something like the following:

import mongoose, { Schema } from 'mongoose';

const userInfoSchema = new Schema({
  createdAt: {
    type: Date,
    required: true,
    default: new Date(),
  },
  // ...other fields
});

const myDB = mongoose.connection.useDb('myDB');

const UserInfo = myDB.model('userInfo', userInfoSchema);

export default UserInfo;

Where myDB is your database name.