multi-db-mongodb

This is a library module which adds multi tenancy capability to mongoose. By default mongoose models are attached to a single mongo db, in scenarios where each tenant(customer) has its own mongo db defined, the logic to switch between mongo dbs gets in middle of business logic. This library helps in abstracting away the multi tenant db switching logic from actual business logic code. This can be used with standalone nodejs scripts or frameworks like expressjs.

Credits

• Orignal Version of mt-mongoose developed by BabuSrithar M.

how it works?

1. It proposes a slight tweak in declaring the mongoose model, such that it gets created every time its called.
2. This library uses continuation-local-storage module to set the tenant db name in the beginning of the code execution.
3. When the model is getting created it attaches the model to the tenenat specific DB it gets from current session of continuation-local-storage.

Defining multi-db-mongodb model

Here is an example of how to create a multi-db-mongodb model

var mongoose = require('mongoose');
var multi_db_mongodb = require("multi-db-mongodb");
User = {
    schema: new mongoose.Schema({
            userid: String,
            firstName: String,
            lastName: String
        }
    ),
    name: "users",
    collectionName: "user" // Optional if collection name is not plural.
    isGlobal: false //attribute to tell if the model is in global DB across tenants or a tenant specific DB 
};
module.exports = function () {
    return multi_db_mongodb.getModel(User);
};

Using multi-db-mongodb model

The multi-db-mongodb model can be used exactly the same way as mongoose model itself. The only deference is an extra function call brackets '()' when initializing. example:

router.get('/index', function (req, res, next) {
    User().find(function (err, users) {
        if (err)
            res.send(err);
        res.json(users);
    });
});

Usage in Express APP(using a middleware)

Create a middleware like this and add it to your app, after mongoose.createConnection is called

   var express = require('express');
    var path = require('path');
    var cookieParser = require('cookie-parser');
    var bodyParser = require('body-parser');
    var methodOverride = require('method-override');
    
    //App initialization and setting default handlers
    var app = express();
    app.use(bodyParser.json());
    app.use(methodOverride());
    
    //Initialization of tenant specific default db and global db
    var mongoose = require('mongoose');
    var tenantDBUri = 'mongodb://localhost/test1'; //this should come from config
    defaultTenantDb = mongoose.createConnection(tenantDBUri);
    var globalDBUri = 'mongodb://localhost/global'; //this should come from config
    globalDb = mongoose.createConnection(globalDBUri);
    var multi_db_mongodb = require("multi-db-mongodb");
    multi_db_mongodb.setDefaultTenantDB(defaultTenantDb); //Set default tenant specific DB
    multi_db_mongodb.setGlobalDB(globalDb); //Set global db across tenants
    
    // Multi tenant middleware
    app.use(function (req, res, next) {
        req._tid = req.query.tid;//example of fetching tenant id from a query parameter, this can be from user object , session etc.
        multi_db_mongodb.setTenantId(req, res, next);
    });
    
    
    //App's routes
    app.get('/index', function (req, res, next) {
        User().find(function (err, users) {
            if (err)
                res.send(err);
            res.json(users);
        });
    });
    
    
    module.exports = app;
    app.listen(3001);

New Features

• Ability to Add DB with URI

var tenantId = "2479ojsdo749jwur";
var tenantDBUri = 'mongodb://localhost/test1'; //this should come from config
multi_db_mongodb.setMultiTenantviaURI(tenantId, tenantDBUri);

• Ability to Add DB After Connection

var tenantId = "2479ojsdo749jwur";
var tenantDBUri = 'mongodb://localhost/test1'; //this should come from config
var tenantDb = mongoose.createConnection(tenantDBUri);
multi_db_mongodb.setMultiTenantviaDB(tenantId, tenantDb);