mongojs not doing CRUD operations - node.js

Question

var connection_string = 'localdb'; //local db by default
var mongojs = require('mongojs');
var collections = ['projects', 'homeAnimationData'];
var db = mongojs(connection_string, collections);
db.homeAnimationData.save({image: '/imagea', width: '200px'}, function(err, saved) {
if( err || !saved ) console.log('not saved');
else console.log('Saved');
});
db.homeAnimationData.find({}).limit(10).forEach(function(err, doc) {
if (err) throw err;
if (doc) {
console.dir(doc);
}
});
None of the consoles are working in nodejs app and I'm not getting any error?

Answer 1

I supect that you are actually calling db.close() but not telling us about it in your question. That, and the case of not seeing the output when you go to .find() data is primarily a problem of the fact that the methods here are 'asynchronous`, and you need to "wait" for the callback execution that you want.
Also the .forEach() method here should be used "sparingly", as it is almost never what you really want in production code. Here is the same thing that works fine with a little async flow control help from the "async" library:
var localdb = 'localdb',
async = require('async'),
mongojs = require('mongojs'),
collections = ['projects','homeAnimationData'],
db = mongojs(localdb,collections);
async.series(
[
function(callback) {
db.homeAnimationData.remove({},callback);
},
function(callback) {
var data = { "image": "/imagea", "width": "200px" };
db.homeAnimationData.save(data,function(err,saved) {
if (err) callback(err);
console.log('Saved');
callback();
});
},
function(callback) {
db.homeAnimationData.find({}).limit(10).toArray(function(err,docs) {
if (err) callback(err);
console.dir(docs);
callback();
});
}
],
function(err) {
if (err) throw err;
db.close();
}
);
Or alternately to calling the .toArray() method, you can use the "stream" interface, which is natively provided:
var localdb = 'localdb',
async = require('async'),
mongojs = require('mongojs'),
collections = ['projects','homeAnimationData'],
db = mongojs(localdb,collections);
async.series(
[
function(callback) {
db.homeAnimationData.remove({},callback);
},
function(callback) {
var data = { "image": "/imagea", "width": "200px" };
db.homeAnimationData.save(data,function(err,saved) {
if (err) callback(err);
console.log('Saved');
callback();
});
},
function(callback) {
var cursor = db.homeAnimationData.find({}).limit(10);
cursor.on('data',function(data) {
cursor.pause();
console.dir(data);
cursor.resume();
});
cursor.on('err',callback);
cursor.on('end',callback);
}
],
function(err) {
if (err) throw err;
db.close();
}
);
In the latter case, this gives you a lot better handling for larger results. The mongojs documtation itself provides and example of .pipe() for a JSONStream.
But everything works fine, you just have to remember this is "async" programming, and logically wait for execution to complete before moving on to some like "reading" the written data back, or indeed closing the database connection.