使用Mongoskin和MongoHQ和Node.js部署到Heroku时遇到问题

Question

I'm currently building a node/express.js app that uses mongoskin. I recently deployed my app to Heroku and having tons of headache with incorporating mongohq to work with my app.

This is the app.js file which I run with node app.js

var express = require("express");
var app = express();
decks = require('./routes/decks');
app.get('/decks', decks.findAll);

My package.json:

{
    "name": "blah blah",
    "description": "Why are there so my blah blah",
    "version": "0.0.1",
    "private": true,
    "dependencies": {
        "express": "3.x",
        "mongodb": "1.1.8",
        "socket.io": "0.9.10"
    },
    "engines": {
        "node": "0.8.4",
        "npm": "1.1.49"
    }
}

After reading the guide on Heroku, I attempt to restructure decks.js and using mongoskin like so.

var mongo = require('mongoskin'); 
var mongoUri = process.env.MONGOHQ_URL;
var db = mongo.db(mongoUri);

exports.findById = function(req, res) {
     var id = req.params.id;
     console.log('Retrieving deck: ' + id);
     db.collection('decks', function(err, collection) {
         collection.findOne({'_id':new BSON.ObjectID(id)}, function(err, item) {
             res.send(item);
         });
     });
 };

However I've been getting the error:

 Please ensure that you set the default write concern for the database by setting    =
=   one of the options                                                                 =
=                                                                                      =
=     w: (value of > -1 or the string 'majority'), where < 1 means                     =
=        no write acknowlegement                                                       =
=     journal: true/false, wait for flush to journal before acknowlegement             =
=     fsync: true/false, wait for flush to file system before acknowlegement           =
=                                                                                      =
=  For backward compatibility safe is still supported and                              =
=   allows values of [true | false | {j:true} | {w:n, wtimeout:n} | {fsync:true}]      =
=   the default value is false which means the driver receives does not                =
=   return the information of the success/error of the insert/update/remove            =
=                                                                                      =
=   ex: new Db(new Server('localhost', 27017), {safe:false})                           =
=                                                                                      =
=   http://www.mongodb.org/display/DOCS/getLastError+Command                           =
=                                                                                      =
=  The default of no acknowlegement will change in the very near future                =
=                                                                                      =
=  This message will disappear when the default safe is set on the driver Db           =
========================================================================================

I've read tons of tutorials but I just cant' get my database working!! Please any help you be appreciated.

Answer 1

Your Db object is using a deprecated setting: "safe".

If you set the "w" option with the write concern you want, that error should go away.

Here's a link to the docs for instantiating that Db object.

http://mongodb.github.io/node-mongodb-native/api-generated/db.html

...

Oh, and you might try updating your uri variable to process.env.MONGOHQ_URL :P

Answer 2

what supershabam said was right

modify this line:

var db = mongo.db(mongoUri);

to this:

var db = mongo.db(mongoUri, {w:1});

this will give you write acknowledgements when performing operations on the database, and make the error go away

for more information on write concerns, check this link out