Mongoose and Multiple Database in Single Node.Js Project

Mongoose and multiple database in single node.js project

One thing you can do is, you might have subfolders for each projects. So, install mongoose in that subfolders and require() mongoose from own folders in each sub applications. Not from the project root or from global. So one sub project, one mongoose installation and one mongoose instance.

-app_root/
--foo_app/
---db_access.js
---foo_db_connect.js
---node_modules/
----mongoose/
--bar_app/
---db_access.js
---bar_db_connect.js
---node_modules/
----mongoose/

In foo_db_connect.js

var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/foo_db');
module.exports = exports = mongoose;

In bar_db_connect.js

var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/bar_db');
module.exports = exports = mongoose;

In db_access.js files

var mongoose = require("./foo_db_connect.js"); // bar_db_connect.js for bar app

Now, you can access multiple databases with mongoose.

Connect multiple mongo db database in node js using mongoose

i believe you are connecting to mongoDB from main entrypoint as index.js or server.js , where you are initiating router. like this
`

    const mongoose = require('mongoose')
    // mongoose
    mongoose.connect("mongoDB url");
    const connection = mongoose.connection;
    connection.on('open',()=>{
        console.log(" database connected")
    })
    connection.on('error',()=>{
        console.log("error in connecting to database")
    })
    app.use(morgan('dev'));
    app.use(bodyParser.urlencoded({extended: false}));
    app.use(bodyParser.json());
    //middlewares`

in same way you can also connect to different databases directly schemas. like in my use case , i wanted to store users in defferent database and posts in another DB .
the in my app.js , i will connect to main DB as normal connection (above) and for user schema , i will connect to my user DB . like this

    const mongoose = require('mongoose');
    const connection = mongoose.createConnection("mongo url ");
    const userSchema = mongoose.Schema({
       name: String,
       date_of_birth: Date
      })
    module.exports = mongoose.model('User', userSchema);

you can also use mongoose.connect() instead of mongoose.createConnection()

hope this helped you.

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