In this lesson, I am going to explain how you can build the Node.js app using the MongoDB and NPM package Mongoose
First, be sure you have MongoDB and Node.js installed
What is Mongoose?
It is an object modelling package. It is same as ORM (Object Relation Mapping) what you find in other languages for Relational Databases access
With Mongoose you can do CRUD operations and easily
First thing you have to do is, installing the Mongoose
In your terminal
$ npm install mongoose --save
After installing the Mongoose package, you can connect to the database using the following two lines in your index.js file
var mongoose = require('mongoose')
mongoose.connect('mongodb://localhost/test',{useMongoClient: true})
So now, we have connected to database
Lets create a model for our collection
Before creating the model, I am going to create a Schema using mongoose.Schema. This model maps with the document in collection
This is the Schema for the product. This Schema just defines the attributes in your document
var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/test',{useMongoClient: true});
var Schema = mongoose.Schema;
var productSchema = new Schema({
product_id:{type:String,required:true,unique:true},
product_name:{type:String,required:true},
unit_price:Number
})
The permitted SchemaTypes are
var Product = mongoose.model('Product', productSchema);
String
Number
Date
Buffer
Boolean
Mixed
ObjectId
Array
When your schema is ready you can create your model now
var Product = mongoose.model('Product', productSchema);
Now lets see how we create new product and save it
var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/test',{useMongoClient: true});
var Schema = mongoose.Schema;
var productSchema = new Schema({
product_id:{type:String,required:true,unique:true},
product_name:{type:String,required:true},
unit_price:Number
})
var Product = mongoose.model('Product', productSchema);
var prdocut= new Product({
product_id:1,
product_name:'Coca Cola',
unit_price:1.25
})
prdocut.save(function(err) {
if (err) throw err;
console.log('Product saved successfully!');
});
Code explanation
save() of the MongooseYou can get all products, only one product, product by id and you can specify the query to get set of products. We will see how we are going to achieve it
Find all products
Product.find({}, function(err, products) {
if (err) throw err;
console.log(products);
});
You will get following output in terminal
[ { _id: 599ac9c41f6e75af47e8140b,
product_id: '1',
product_name: 'Coca Cola',
unit_price: 1.25,
__v: 0 },
{ _id: 599ad83c9cd889afaf5fc800,
product_id: '2',
product_name: 'Fanta',
unit_price: 1.35,
__v: 0 },
{ _id: 599ad86506f67fafb26d74b8,
product_id: '3',
product_name: 'Sprite',
unit_price: 1.45,
__v: 0 } ]
Find one product
To find one product, you have to specify the product attribute so that Mongoose can locate it
var product={product_name:'Coca Cola'}
Product.find(product, function(err, product) {
if (err) throw err;
console.log(product);
});
Terminal Output
[ { _id: 599ac9c41f6e75af47e8140b,
product_id: '1',
product_name: 'Coca Cola',
unit_price: 1.25,
__v: 0 } ]
Find product by Id
Product.findById('599ad83c9cd889afaf5fc800', function(err, product) {
if (err) throw err;
console.log(product);
});
Find product by querying
You can find product by making query. MongoDB has good query syntax. You can refer it for more details
In this example I am going to find products which unit prices are greater than 1.25
Product.find({}).where('unit_price').gt(1.25).exec(function(err, products) {
if (err) throw err;
console.log(products);
});
Terminal Output
[ { _id: 599ad83c9cd889afaf5fc800,
product_id: '2',
product_name: 'Fanta',
unit_price: 1.35,
__v: 0 },
{ _id: 599ad86506f67fafb26d74b8,
product_id: '3',
product_name: 'Sprite',
unit_price: 1.45,
__v: 0 } ]
There are several ways to do update document with Mongoose
First you can get the object and then update the attributes and finally save it. You can use findById() or findOne() to get the product object.
Other method is using the findOneAndUpdate()
Third one is findByIdAndUpdate()
We will how these methods one by one
Find the product first, then update
var product={product_name:'Coca Cola'}
Product.findOne(product, function(err, product) {
if (err) throw err;
product.unit_price=2
product.save()
console.log(product);
});
You can use findById() to get the product
Product.findById('599ac9c41f6e75af47e8140b', function(err, product) {
if (err) throw err;
product.unit_price=2
product.save()
console.log(product);
});
Using findOneAndUpdate()
var query={product_name:'Coca Cola'}
var updated={unit_price:2.00}
Product.findOneAndUpdate(query,updated, function(err, product) {
if (err) throw err;
console.log("Update Done");
});
Using findByIdAndUpdate()
var updated={unit_price:2.00}
Product.findByIdAndUpdate('599ac9c41f6e75af47e8140b',updated, function(err, product) {
if (err) throw err;
console.log("Update Done");
});
Those are the several method of updating the document. You can use the correct one according your requirements
To delete the document first you have to find it. There are several methods to delete document. It is same like what you learned in update document
Find the product first, then delete
var product={product_name:'Coca Cola'}
Product.findOne(product, function(err, product) {
if (err) throw err;
product.delete()
console.log(product);
});
Using findOneAndRemove()
var product={product_name:'Coca Cola'}
Product.findOneAndRemove(product, function(err) {
if (err) throw err;
console.log("Product dleted");
});
Using findByIdAndRemove()
Product.findByIdAndRemove('599ac9c41f6e75af47e8140b', function(err) {
if (err) throw err;
console.log('Product deleted');
});
I hope that you have good understanding to work with Mongoose and Node.js to build your application now