I'm using node-mongodb-native driver with mongodb to write a website.
I have a question about how to open mongodb connection once, then use it in collection name users in user.js
and collection name posts in comment.js
I want to open db connection in db.js
then to insert / save data for users and posts collection
Currently code,my db.js
var Db = require('mongodb').Db,
Connection = require('mongodb').Connection,
Server = require('mongodb').Server;
module.exports = new Db(
'blog',
new Server('localhost', Connection.DEFAULT_PORT, {auto_reconnect: true})
);
I used db.js
in user.js
as follow
var mongodb = require('./db');
function User(user){
this.name = user.name;
this.password = user.password;
this.email = user.email;
};
module.exports = User;
User.prototype.save = function(callback) {//save user information
//document to save in db
var user = {
name: this.name,
password: this.password,
email: this.email
};
mongodb.close();
//open mongodb database
mongodb.open(function(err, db){
if(err){
return callback(err);
}
//read users collection
db.collection('users', function(err, collection){
if(err){
mongodb.close();
return callback(err);
}
//insert data into users collections
collection.insert(user,{safe: true}, function(err, user){
mongodb.close();
callback(err, user);//success return inserted user information
});
});
});
};
and comment.js
var mongodb = require('./db');
function Comment(name, day, title, comment) {
this.name = name;
this.day = day;
this.title = title;
this.comment = comment;
}
module.exports = Comment;
Comment.prototype.save = function(callback) {
var name = this.name,
day = this.day,
title = this.title,
comment = this.comment;
mongodb.open(function (err, db) {
if (err) {
return callback(err);
}
db.collection('posts', function (err, collection) {
if (err) {
mongodb.close();
return callback(err);
}
//depend on name time and title add comment
collection.findAndModify({"name":name,"time.day":day,"title":title}
, [ ['time',-1] ]
, {$push:{"comments":comment}}
, {new: true}
, function (err,comment) {
mongodb.close();
callback(null);
});
});
});
};
You can connect once, and then reuse it as many times as you want:
var mongodb = require('mongodb');
var events = require('events');
var event = new events.EventEmitter();
var access = new mongodb.Server(host, port, { });
var client = null;
new mongodb.Db('YOUR DATABASE', access, { safe: true, auto_reconnect: true }).open(function (err, c) {
if (!err) {
client = c;
console.log('database connected');
event.emit('connect');
} else {
console.log('database connection error', err);
event.emit('error');
}
});
exports.get = function(fn) {
if(client) {
fn(client);
} else {
event.on('connect', function() {
fn(client);
});
}
};
And then reuse it:
var db = require('./db');
var items;
db.get(function(client) {
items = new mongodb.Collection(client, 'collection');
});
// then anywhere in your code
db.get(function() {
// items.find({ ...
});
Accepted answer is 3 year old and it wont work with latest node-mongodb-native driver. I have modified @moka answer and added some delay and retry logic.
var MongoClient = require('mongodb').MongoClient;
var events = require('events');
var event = new events.EventEmitter();
var database = null;
var retries = 0;
var delay = 300;
setTimeout(connect,delay);
// Use connect method to connect to the server
function connect(){
MongoClient.connect(process.env.MONGODB_URL, function(err, db) {
if(!err){
console.log("Connected successfully to server");
database = db;
event.emit('dbconnect');
} else {
if(retries < 4){
console.log('Retrying to connect db %s', retries++);
setTimeout(connect,delay);
} else {
console.log('Unable to connect db');
}
}
});
}
exports.get = function(fn) {
if(database !== null) {
fn(database);
} else {
event.on('dbconnect', function() {
fn(database);
});
}
};
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