express-mongo-db

Middleware that creates only one connection, that initialized before first request is recieved and shares it for all next incoming requests.

Usage

First - install middleware in project:

npm i express-mongo-db mongodb --save

Second - add middleware to express application:

var app = require('express')();
app.use(require('express-mongo-db')(require('mongodb')));

Now you got req.db object of Mongodb database in every request handler.

API

express-mongo-db(mongodb, [options])

Creates middleware with passed mongodb module instance (this is useful for promisification).

Options

You can pass options to constructor of middleware function like this: require('express-mongo-db')(options) where options is an object with fields described below.

Also you can modify defaults value in config property of middleware contructor like this:

var mongodb = require('express-mongo-db');
mongodb.config.readPreference = 'secondary';

var app = require('express')();
app.use(mongodb(require('mongodb')));

app.get('/', function(req, res) {
    req.db.find(/* ... */);
});

• hosts - servers or replicas array (default: [{host: '127.0.0.1', port: 27017}])
• db - name of database (default: test)
• options - object, that passed to
• name - user name for authentication
• pwd - password for authentication
• MongoClient.connect.
• And all options from connect-once, such as reconnectWait and heartbeat function.

Events

To know what's up in your life, we provide event-emitter to listen to. For example - this is how you know, that reconnecton happening:

var mongodb = require('express-mongo-db')(require('mongodb'), options);
mongodb.connection.on('reconnect', function(err) {
    console.log("Reconnecting to mongo (" + this.retries + " retries left). " + (err.stack ? err.stack : err));
});

Also you can subscribe on connection event:

var mongodb = require('express-mongo-db')(require('mongodb'), options);
mongodb.connection.when('available', function(err, db) {

});

express-mongo-db will start attempts to connect straight after require.