Using Sequelize MySQL with NestJS

Sequelize is a popular Object-Relational Mapping (ORM) library for Node.js that provides a simple way to interact with relational databases such as MySQL. In this article, we will explore how to use Sequelize with MySQL in a NestJS application by providing an example code fragment of only the model code.

Prerequisites

Before we get started, make sure that you have the following installed on your system:

Node.js
NestJS CLI
MySQL server
Sequelize ORM

Setting up a NestJS application with Sequelize and MySQL

To begin, create a new NestJS application by running the following command:

$ nest new my-app

Next, navigate into the newly created project directory and install the necessary dependencies:

``` $ cd my-app $ npm install --save @nestjs/sequelize sequelize mysql2 ```

Now, let's create a new Sequelize configuration file in a new folder called "config" at the root of the project directory. Create a file named "database.config.ts" and add the following code:

import { Sequelize } from 'sequelize-typescript';

export const databaseConfig: Sequelize = new Sequelize({
dialect: 'mysql',
host: 'localhost',
port: 3306,
username: 'root',
password: 'password',
database: 'my_database',
define: {
timestamps: true,
},
});

This configuration file sets up a new instance of Sequelize and connects it to a MySQL database running on the local machine.

Creating a Sequelize model in NestJS

Now that we have our Sequelize instance set up, let's create a new model in NestJS. Create a new file in the "src" directory called "user.model.ts" and add the following code:

import { Table, Column, Model } from 'sequelize-typescript';

@Table({ tableName: 'users' })
export class User extends Model {

@Column({ primaryKey: true, autoIncrement: true })
id: number;

@Column({ allowNull: false })
name: string;

@Column({ allowNull: false })
email: string;

@Column({ allowNull: false })
password: string;
}

This model defines a new "User" table in the MySQL database with columns for "id", "name", "email", and "password". The "@Table" decorator sets the name of the table in the database, and the "@Column" decorator sets the properties of each column.

Using the Sequelize model in NestJS

Finally, let's use our new Sequelize model in a NestJS controller. Create a new file in the "src" directory called "user.controller.ts" and add the following code:

typescript

import { Controller, Get } from '@nestjs/common';
import { InjectModel } from '@nestjs/sequelize';
import { User } from './user.model';

@Controller('users')
export class UserController {
constructor(
@InjectModel(User)
private readonly userModel: typeof User,
) {}

@Get()
async findAll(): Promise<User[]> {
return this.userModel.findAll();
}
}

This controller uses the "@InjectModel" decorator to inject the "User" model into the class. The "findAll" method returns all users from the database using the "findAll" method provided by Sequelize.

Conclusion

In this article, we explored how to use Sequelize with MySQL in a NestJS application by providing an example code fragment of only the model code. We created a new Sequelize instance, defined a new Sequelize model, and used that model in a NestJS controller. By following this guide, you should now have a basic understanding of how to use Sequelize with MySQL in a NestJS application.

Using Sequelize MySQL with NestJS ​

Prerequisites ​

Setting up a NestJS application with Sequelize and MySQL ​

Creating a Sequelize model in NestJS ​