What is Mongoose?
Mongoose is an “elegant mongodb object modeling for node.js“. If you have used MongoDB before and tried basic database operations, you might have noticed that MongoDB is “schema less”. When you are looking to implement a more structured database and want to leverage the power of MongoDB, Mongoose is one of the ODM (Object Data Mapping) solutions.
To quickly demonstrate, you run an insert command into a collection named users like
db.users.insert({ name : 'Arvind', gender : 'male'});
And right after that you can run
db.users.insert({ name : 'Arvind', gender : 'male', password : '!@#$'});
and MongoDB will never complain about the variation in the number of columns (key value pairs). This is very flexible. But when you want to keep your data more organized and structured, you would need to maintain that in your server code, writing validation, making sure nothing irrelevant is stored in a collection. And this is where Mongoose makes life easy.
“Mongoose provides a straight-forward, schema-based solution to modeling your application data and includes built-in type casting, validation, query building, business logic hooks and more, out of the box.”
Install Node js & MongoDB
To use Mongoose, we need to have Node js installed, you can find info here.
Start Developing
Let us first create a small playground, where we can have fun. Create a new folder named myMongooseApp. And open terminal/prompt here and run
npm init
This will help us in initializing a new node project. Fill it up as required. Next, we will install Mongoose as a dependency to our project. Run
npm install mongoose --save-dev
then start the MongoDB service by running
mongod
Next, create a new file named index.js at the root of the and then open it up in your favorite editor. And add the below code.
var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/myTestDB');
var db = mongoose.connection;
db.on('error', function (err) {
console.log('connection error', err);
});
db.once('open', function () {
console.log('connected.');
});
Here, we require the mongoose package to connect to the DB, and initialize the connection. The name of our Database is myTestDB.
Then run
node index.js
and you should see the connected message. You can also use a node package named nodemon for automatically restarting the node server on changes.
Now, our sandbox is ready to play!
Mongoose Schemas
Schemas are like skeletons. The bare bones of how your data collection will look like. If you are dealing with a collection of users, your schema would look something like this.
Name - String Age - Number Gender - String Date of Birth - Date