Mongoose est un Object Document Mapping Library, l'equivalent de sequelize pour mysql.

https://mongoosejs.com/

npm i --save mongoose

const mongoose = require("mongoose")

mongoose.connect("mongodb+srv://6ssou:[email protected]/
shop?retryWrites=true&w=majority")
.then(() => {
	app.listen(3000);
}).catch(err => {
	console.log(err)
}) 

CREATE SCHEMA

// models/product.js
const mongoose = require("mongoose");
const Schema = mongoose.Schema;
const productSchema = new Schema({
  title: {
    type: String,
    required: true
  },
  price: {
    type: Number,
    required: true
  },
  description: {
    type: String,
    required: true
  },
  imageUrl: {
    type: String,
    required: true
  },
	userId: {
    type: Schema.Types.ObjectId,
    ref: 'User'
  }
})

// to connect the model to a name
// mongoose will take this name, turn it into lowerCase then plural 
// this will be the collection name !
module.exports = mongoose.model('Product', productSchema);

SAVE DATA :

exports.postAddProduct = (req, res, next) => {
  const title = req.body.title;
  const imageUrl = req.body.imageUrl;
  const price = req.body.price;
  const description = req.body.description;
// here we pass an object with key: value pairs
 const product = new Product({
    title: title,
    price: price,
    description: description,
    imageUrl: imageUrl,
    userId: req.user
  })
  product
  // save is provided by mongoose!
  .save()
    .then(() => {
      res.redirect('/admin/products');
    })
    .catch(err => {
      console.log(err);
    });
};

RETRIEVE DATA

exports.getProducts = (req, res, next) => {
// we use find here wich is provided by mongoose
  Product.find()
    .then(products => {
      console.log(products)
      res.render('shop/product-list', {
        prods: products,
        pageTitle: 'All Products',
        path: '/products'
      });
    })
    .catch(err => {
      console.log(err);
    });
};

FIND BY ID

C'est la même méthode qu'avec mongodb classique :

Product.findById(prodId).then( .. .. )

EDIT BY ID :

exports.postEditProduct = (req, res, next) => {
  const prodId = req.body.productId;
  const updatedTitle = req.body.title;
  const updatedPrice = req.body.price;
  const updatedImageUrl = req.body.imageUrl;
  const updatedDesc = req.body.description;
// when we call save on a existing product, it updates it
  Product.findById(prodId).then(product => {
    product.title = updatedTitle,
    product.pricen = updatedPrice,
    product.description = updatedDesc,
    product.imageUrl = updatedImageUrl
// product.save is created by mongoose
    return product.save()
  }).then(() => {
    res.redirect('/admin/products');
  })
  .catch(err => console.log(err));
};

DELETE BY ID :

exports.postDeleteProduct = (req, res, next) => {
  const prodId = req.body.productId;
		// Product.findByIdAndRemove(prodId)
    Product.deleteOne({_id: mongodb.ObjectId(prodId)}).then(result => {
      res.redirect("/admin/products")
    })
    .catch(err => console.log(err));
};

CREATE A USER MODEL

const mongoose = require("mongoose");
const Schema = mongoose.Schema;

const userSchema = new Schema({
  name: {
    type: String,
    required: true
  },
  email: {
    type: String,
    required: true
  },
  cart: {
      items: [{
          productId: {
              type: Schema.Types.ObjectId,
							ref: 'Product',
              required: true
          },
          quantity: {
              type: Number,
              required: true
          }
      }]
  }
});
module.exports = mongoose.model("User", userSchema)

//app.js       
// Get user 
app.use((req, res, next) => {
  User.findById("5ed0dff41f49081c9c3d7872")
    .then(user => {
      req.user = user
      console.log(req.user)
      next();
    })
    .catch(err => console.log(err));
});

db().then(result => {
  User.findOne().then(user => {
    if(!user) {
      const user = new User({
        name: 'Satoshi',
        email: '[email protected]',
        cart: {
          items: []
        }
      });
      user.save();
    }
  })
  app.listen(3000)