AliIybar: Created page with "Category:Node.js Category:ORM Category:Database == Installation == npm install --save sequelize drivers for databases: npm install --save pg pg-hstore #Postgre..."

2021-11-25T12:28:42Z

Created page with "Category:Node.js Category:ORM Category:Database == Installation == npm install --save sequelize drivers for databases: npm install --save pg pg-hstore #Postgre..."

New page

[[Category:Node.js]]
[[Category:ORM]]
[[Category:Database]]

== Installation ==
npm install --save sequelize
drivers for databases:
npm install --save pg pg-hstore #Postgres
npm install --save mysql2
npm install --save mariadb
npm install --save sqlite3
npm install --save tedious #Microsoft SQL Server

== Establish Database Connection ==
in '''./util/database.js'''
<pre>
const Sequelize = require("sequelize");

const sequelize = new Sequelize("your_db_name", "your_username", "your_password", {
dialect: "mysql",
host: "localhost", //Optional
});
module.exports = sequelize;
</pre>
== Define Models ==
in '''./models/customer.js'''
<pre>
const Sequelize = require("sequelize");
const sequelize = require("../util/database");

const Customer = sequelize.define("customer", {
id: {
type: Sequelize.INTEGER,
autoIncrement: true,
allowNull: false,
primaryKey: true,
},
name: {
type: Sequelize.STRING,
allowNull: false,
},
email: {
type: Sequelize.STRING,
allowNull: false,
},
});

module.exports = Customer;
</pre>
in '''./models/order.js'''
<pre>
const Sequelize = require("sequelize");

const sequelize = require("../util/database");

const Order = sequelize.define("order", {
id: {
type: Sequelize.INTEGER,
autoIncrement: true,
allowNull: false,
primaryKey: true,
},
total: {
type: Sequelize.INTEGER,
allowNull: false,
},
});

module.exports = Order;
</pre>
== Create DB Tables from Sequelize Models ==
<pre>
const sequelize = require("./util/database");

const Customer = require("./models/customer");
const Order = require("./models/order");

sequelize
.sync()
// .sync({force: true})
.catch((err) => {
console.log(err);
});
</pre>
== Relations ==
<pre>
const sequelize = require("./util/database");

const Customer = require("./models/customer");
const Order = require("./models/order");

Customer.hasMany(Order);

sequelize
.sync()
.catch((err) => {
console.log(err);
});
</pre>
* The HasOne association
* The BelongsTo association
* The HasMany association
* The BelongsToMany association
=== onDelete and onUpdate ===
For example, to configure the ON DELETE and ON UPDATE behaviors, you can do:
<pre>
Foo.hasOne(Bar, {
onDelete: 'RESTRICT',
onUpdate: 'RESTRICT'
});
Bar.belongsTo(Foo);
</pre>

=== Many To Many ===
<pre>
const Movie = sequelize.define('Movie', { name: DataTypes.STRING });
const Actor = sequelize.define('Actor', { name: DataTypes.STRING });
Movie.belongsToMany(Actor, { through: 'ActorMovies' });
Actor.belongsToMany(Movie, { through: 'ActorMovies' });
</pre>
=== Lazy Loading example ===
<pre>
const awesomeCaptain = await Captain.findOne({
where: {
name: "Jack Sparrow"
}
});
// Do stuff with the fetched captain
console.log('Name:', awesomeCaptain.name);
console.log('Skill Level:', awesomeCaptain.skillLevel);
// Now we want information about his ship!
const hisShip = await awesomeCaptain.getShip();
// Do stuff with the ship
console.log('Ship Name:', hisShip.name);
console.log('Amount of Sails:', hisShip.amountOfSails);
</pre>
=== Eager Loading Example ===
<pre>
const awesomeCaptain = await Captain.findOne({
where: {
name: "Jack Sparrow"
},
include: Ship
});
// Now the ship comes with it
console.log('Name:', awesomeCaptain.name);
console.log('Skill Level:', awesomeCaptain.skillLevel);
console.log('Ship Name:', awesomeCaptain.ship.name);
console.log('Amount of Sails:', awesomeCaptain.ship.amountOfSails);
</pre>
== Writing Queries ==
In the following code snippet, we perform the following actions:

# Insert a new customer
# Insert a new order for this customer using the customerId foreign key.
# Select all the orders for the current customer.
<pre>
const sequelize = require("./util/database");

const Customer = require("./models/customer");
const Order = require("./models/order");

Customer.hasMany(Order);

let customerId = null;
sequelize
.sync()
.then((result) => {
return Customer.create({name: "Chandler Bing", email: "cb@gmail.com"})
console.log(result);
})
.then(customer => {
customerId = customer.id;
console.log("First Customer Created: ",customer);
return customer.createOrder({total: 45});
})
.then(order => {
console.log("Order is : ",order);
return Order.findAll({ where: customerId});
})
.then(orders => {
console.log("All the Orders are : ",orders);
})
.catch((err) => {
console.log(err);
});
</pre>

Sequelize - Revision history

AliIybar: Created page with "Category:Node.js Category:ORM Category:Database == Installation == npm install --save sequelize drivers for databases: npm install --save pg pg-hstore #Postgre..."