Having spent a significant amount of time researching how to set up MongoDb in an Express/NodeJs application, I believed I had a good understanding of how to implement it efficiently. I decided to initialize my mongodbConnection in the WWW file provided by Express, ensuring that only one connection is opened when the app starts.
WWW
!/usr/bin/env node
var debug = require('debug')('myapp');
var app = require('../app');
var mongoConnection = require('../mongo/mongoconnection.js');
mongoConnection.init(function(error){
// Start the application after the database connection is ready
app.set('port', process.env.PORT || 3000);
var server = app.listen(app.get('port'), function() {
debug('Express server listening on port ' + server.address().port);
});
});
The actual initialization of the database is worked out in my mongoConnection.js file where I export the database variable.
mongoconnection.js
var mongodb = require('mongodb');
var bson = mongodb.BSONPure;
var MongoClient = mongodb.MongoClient;
// Initialize connection once
module.exports.init = function(callback)
{
MongoClient.connect("mongodb://localhost:27017/capturemongo", function(err, database) {
if(err) throw err;
module.exports.db = database;
callback(err);
});
};
However, when trying to access the database variable from my mastermanager.js file, the db variable appears to be undefined.
mastermanager.js
var mongoConnection = require('./mongoconnection.js');
var db = mongoConnection.db;
module.exports.getCollection = function( callback){
db.collection('masters', function(err, collection){
if(!err){
callback(null, collection);
}
else{
console.log("getcolelction error " + err);
callback(err);
}
});
};
module.exports.findAll = function(callback) {
this.getCollection(function(error, collection) {
if( error ){
callback(error);
}
else {
collection.find().toArray(function(error, results) {
if( error ) {
callback(error);
console.log('finderror ' + error);
}
else{
console.log(results);
callback(null, results);
}
});
}
});
};
I am struggling to understand why the variable is undefined there. When adding console.log() statements in the init of mongoconnection, it clearly shows that the database variable is set!
Any assistance would be greatly appreciated!