Project Setup - পাইথন বাংলা টিউটোরিয়াল

Step 1: Project Setup

Initialize the ProjectFirst, create a new directory for your project and initialize it with npm:

mkdir express-backend-boilerplate
cd express-backend-boilerplate
npm init -y

Install Dependencies

Install the necessary dependencies for the project:

npm install express reflect-metadata
npm install --save-dev nodemon
npm install typeorm -D

// For Mysql
npm install mysql2 

// for sqlite
npm install sqlite3

express: The web framework for building the API.
typeorm: ORM for interacting with the database.
mysql2: MySQL driver.
reflect-metadata: Used by TypeORM for decorators.
nodemon: Automatically restarts the server when file changes are detected.

Setup Scripts in package.json

Update the scripts section in your package.json to include a start script with nodemon:

"scripts": {
  "start": "nodemon src/index.js"
}

Create the Project Structure

Organize the project with the following directory structure:

express-backend-boilerplate/
├── src/
│   ├── config/
│   │   └── ormconfig.js       // Database configuration
│   ├── index.js               // Entry point
│   ├── modules/
│   │   └── student/           // Student module
│   │       ├── controllers/
│   │       ├── entities/
│   │       ├── routes/
│   │       ├── services/
│   │       └── studentModule.js // Student module initialization
├── .env                       // Environment variables
└── package.json

Step 2: Configure the Database

Create ormconfig.jsIn the src/config/ directory, create a ormconfig.js file to define the database configuration:

module.exports = {
    type: 'mysql',
    host: 'localhost',
    port: 3306,
    username: 'root',
    password: 'your_password',
    database: 'your_database_name',
    entities: ['src/modules/**/entities/*.js'], // Ensure this path is correct for your entity files
    migrations: ['src/migrations/*.js'], // Ensure this path is correct for your migration files
    cli: {
      migrationsDir: 'src/migrations', // Directory where new migrations will be generated
    },
    synchronize: false, // Turn off synchronization when using migrations
    logging: true, // Enable logging for debugging (optional)
};

for sqlite3

module.exports = {
  type: 'sqlite',
  database: 'database.sqlite', // SQLite database file
  entities: ['src/modules/**/*.js'], // Auto-load entities from modules
  migrations: ['src/migrations/*.js'], // Specify the migrations directory
  cli: {
    migrationsDir: 'src/migrations', // Directory where new migrations will be generated
  },
  synchronize: false, // Turn off synchronization when using migrations
  logging: true, // Enable logging for debugging (optional)
};

synchronize: true will automatically sync your database schema with your entities. Set this to false in production.

Setup .env File

Create a .env file in the root of the project for environment variables:

touch .env

Add your database credentials:

DB_HOST=localhost
DB_PORT=3306
DB_USERNAME=root
DB_PASSWORD=password
DB_NAME=express_backend_boilerplate

Step 3: Initialize the Application

Setup index.jsCreate the entry point index.js in the src/ directory:

require('dotenv').config(); // Load environment variables
require('reflect-metadata'); // Required by TypeORM for decorators

const express = require('express');
const { DataSource } = require('typeorm');
const ormConfig = require('./config/ormconfig');

// Initialize TypeORM DataSource
const AppDataSource = new DataSource(ormConfig);

const initializeApp = async () => {
  // Initialize DataSource
  await AppDataSource.initialize();
  console.log('Database connected successfully!');

  // Initialize Express app
  const app = express();

  // Configure middlewares
  app.use(express.json());


  // Start the server
  const PORT = process.env.PORT || 3000;
  app.listen(PORT, () => {
    console.log(`Server running on port ${PORT}`);
  });
};

initializeApp().catch((error) => {
  console.error('Error initializing app:', error);
});

// Export the AppDataSource for TypeORM CLI usage
module.exports = {
  AppDataSource,
};

AppDataSource: This is the TypeORM DataSource instance, initialized with our ormconfig.js.

studentModule.routes: Here, we’re going to import the routes from our Student module and mount them on the /api/students path.

Generate the Migration

Now that your AppDataSource is exported, you can run the migration generation command again:

npx typeorm migration:generate src/migrations/database-initial -d src/index.js -o

Apply the Migration

If the migration is generated successfully, apply it using:

npx typeorm migration:run -d src/index.js

Run the Project

Now that the libraries are installed, you can proceed to run your project with:

npm start

ExpressJs