How to Perform Multiple Inner Joins in Sequelize Postgresql - node.js

Question

Am newbie to RDBMS and Sequelize as well wanted to explore more in those now am struck up with JOINS. I don't know how to perform JOINS via SEQUELIZE. I have 3 tables USERS,ORDERS,PRODUCTS ORDERS table contains USERS,PRODUCTS primary key as its foreign key. Am attaching my model code below
User Model
const Sequelize = require('sequelize');
const sequelize = require('../config');
let Users = sequelize.define('users', {
id : {
type: Sequelize.INTEGER,
primaryKey: true,
autoIncrement: true
},
username: {
type: Sequelize.STRING,
},
password: {
type: Sequelize.STRING
}
});
module.exports = Users;
Products Model
const Sequelize = require('sequelize');
const sequelize = require('../config');
let products=sequelize.define('products', {
id : {
type: Sequelize.INTEGER,
primaryKey: true,
autoIncrement: true
},
category : {
type: Sequelize.STRING,
allowNull: false
},
name : {
type: Sequelize.STRING,
allowNull: false
},
price: {
type: Sequelize.INTEGER,
allowNull: false
}
});
module.exports= products;
Orders Model
const Sequelize = require('sequelize');
const sequelize = require('../config');
let users=require('./user');
let products=require('./product');
let orders=sequelize.define('orders', {
id: {
type: Sequelize.INTEGER,
primaryKey: true,
autoIncrement: true
},
user_id: {
type: Sequelize.INTEGER,
references: {
model: 'users',
key: 'id'
}
},
product_id: {
type: Sequelize.INTEGER,
references: {
model: 'products',
key: 'id'
}
},
price: {
type: Sequelize.INTEGER,
allowNull: false
}
});
module.exports= orders;
I want this following raw query to be performed via SEQUELIZE
SELECT * FROM ((orders INNER JOIN users ON users.id=orders.user_id) INNER JOIN products ON products.id=orders.product_id);
I have looked at the documentation but i couldn't figure out how to do it. ANy help is appreciated. Thanks

Answer 1

First thing you need to do is set up your Associations.
So lets break this up in to parts. We know that your ORDERS table contains the id for a USER and a PRODUCT. So this is how you would set up your associations for these tables.
I am assuming that a user has many orders. We make the associations in both directions.
User.hasMany(Orders, {foreignKey: 'user_id'});
Order.belongsTo(User, {foreignKey: 'user_id'});
You have the model correctly defined it seems.
Now in order to do a join, after setting up the associations, we want to set up a query to do joins for tables. Now keep in mind this would be done in your controller.
// Make sure you import your models up here to use below
export function getRequestsByWeek(req, res) {
return order.findAll({
include: [
{model: users, attributes: []}, // nothing in attributes here in order to not import columns from users
{model: products} // nothing in attributes here in order to not import columns from products
],
attributes: ['id'], //in quotes specify what columns you want, otherwise you will pull them all
// Otherwise remove attributes above this line to import everything.
})
.then(respondWithResult(res))
.catch(handleError(res));
}

Answer 2

let users=require('./user');
let products=require('./product');
export function getOrders(req, res) {
return order.findAndCountAll({
include: [
{model: users, required: true}, // true for INNER JOIN
{model: products, required: false} // false for LEFT OUTER JOIN
],
them all
})
}