In this blog we will see how to interact with mongodb through nodejs. We will use the mongoose library for this
I will be using this library http://mongoosejs.com/ to intract with mongodb. I assume that you already know the basics of mongodb and have installed it.
Basic Setup
In mongoose you need first create a schema for your table in your code and then create a model from the scheme. But i will just the fast and easy to do it.
Lets assume the name of our database is “blog” and table is “post”
var mongoose = require('mongoose');
var conn = mongoose.createConnection('mongodb://127.0.0.1/blog');
var post_schema = mongoose.Schema({}, {
strict: false,
collection: 'post'
});
var post = conn.model('post', post_schema);
Above we have create a basic model to run our queries on mongodb. The scheme is empty and we have set strict: false, so this allows us to skip the schema definition.
Basic CRUD Operations
Continuing from the above, lets Read and Insert Operation First
var mongoose = require('mongoose');
var conn = mongoose.createConnection('mongodb://127.0.0.1/blog');
var post_schema = mongoose.Schema({}, {
strict: false,
collection: 'post'
});
var post = conn.model('post', post_schema);
//Read from database, supports all mongo where conditions
post.find({
title: /Test/i
}, function (err, result) {
if (err) {
console.log(err);
process.exit();
}
if (!result || result.length == 0) {
var new_post = new post({
title: 'Test Title',
cat_id: 1,
date: new Date() + ""
});
new_post.save(function (err) {
//save done
if (err) {
console.log(err);
process.exit();
}
console.log('Post Saved')
});
} else {
for (var i = 0; i < result.length; i++) {
var row = result[i];
var id = row.get('_id');
var title = row.get('title');
var cat\_id = row.get('cat\_id');
console.log('Title: ' + title + 'in category: ' + cat\_id + ' with \_id: ' + id);
}
}
});
Now let us see how to Update
var mongoose = require('mongoose');
var conn = mongoose.createConnection('mongodb://127.0.0.1/blog');
var post_schema = mongoose.Schema({}, {
strict: false,
collection: 'post'
});
var post = conn.model('post', post_schema);
var objectID = new mongoose.Types.ObjectId('54549d4b2db33af6045d4ec1');
post.find({
"_id": objectID
}, function(err, docs) {
if (!err) {
if (docs.length > 0) {
var row = docs[0];
post.update({
'\_id': row.get('\_id')
}, {
$set: {
title: 'Updated Title'
}
}, function(err) {
if (!err) {
console.log('Update Done');
}
});
}
else {
console.log('Not Found');
}
}
});
In the above code I have also used “mongoose.Types.ObjectId” which is used for ‘_id’ in mongodb. You can see above how it can be used in find() and how to get('_id’) it.
To delete a row, we can simply use the remove() function just like save() and find().
Insert Multiple Rows Together And Callback when done
We will see a very common case, suppose we have an array of records. We need to insert all of them in mongodb and when done we need to continue. Since save row is an async operation, we will see how to go about it.
var mongoose = require('mongoose');
var conn = mongoose.createConnection('mongodb://127.0.0.1/blog');
var post_schema = mongoose.Schema({}, {
strict: false,
collection: 'post'
});
var post = conn.model('post', post_schema);
var records = [];
for (var i = 0; i < 10; i++) {
records.push({
title: 'Title Number ' + Math.random(1000),
'cat_id': 1
});
}
insertAndNotify(records, function(err) {
if (err) {
console.log(err);
process.exit();
}
console.log('all done!!');
process.exit();
//continue all insert is done
});
function insertAndNotify(records, callback) {
var inserted = 0;
for (var i = 0; i < records.length; i++) {
(function(row) {
//anonymouse function for scope
var new_post = new post({
title: row.title,
cat\_id: row.cat\_id * 1,
date: new Date() + ""
});
new_post.save(function(err, row) {
if (err) {
console.log(err);
}
else {
inserted++;
if (inserted == records.length) {
callback();
}
}
});
})(records[i]);
}
}
A Faster Mass Insert using async
In a previous blog post we have seen show to use async library. We will use that make a faster insert
function insertAndNotify(records, main_callback) {
async.eachLimit(records, 5, function(row, callback) {
var new_post = new post({
title: row.title,
cat\_id: row.cat\_id * 1,
date: new Date() + ""
});
new_post.save(function(err, row) {
if (err) {
console.log(err);
callback(err);
}
else {
callback();
}
});
}, function(err) {
main_callback(err);
});
}
In the above function, we are doing a parallel processing of 5 insert at a time hence will increase speed.
The same concept can be extended to remove and update as well.
We will see some of the advance operations which can be done using mongoose.
Load By ID
This is a very frequency use case where we need to find information based on ObjectID.
Below is the way to do it
Model.findOne({
\_id: mongoose.Types.ObjectId(model\_id)
}
Lean Models
When we do a find or findOne operation on collections, the result which we get a big mongoose object. Instead if you want to get bare bone json object here is the way to do it.
Model.find().lean().exec(function(err,result){
console.log(result); //json object
});
Sort, Skip, Limit
There are various standard operations we can perform
Model.find().sort({date:-1}).skip(5).limit(10).exec(function(err,result){
});
$or condition
Another frequently used operation is the $or condition. All ‘where’ condition in mongo are by default ‘$and’ operations, if we want ‘$or’ we need to do something like this
Model.find({
$or : [
{isd : '54853e4e905437385a8b4567'},
{store : '547ffe9c90543793128b4568'}
],
date : '2014-12-12'
})
So as per above where condition, isd & store are in $or , date is $and.
