How to set up typeorm .env file?

The .env file is a custom environment file used by TypeORM to configure database connection options. In TypeORM, the default configuration files are ormconfig.json, ormconfig.js, ormconfig.yml, etc., but you can specify different files or set the configuration directly in environment variables.

If you want to use the .env file to configure TypeORM, you should first install the dotenv library to load environment variables from the .env file. Here are the steps to do it:

1. Install the dotenv library:

shell
npm install dotenv

1. Create the .env file:

Create a .env file in the root directory of your project and set your database connection options in it. For example:

shell
# .env
TYPEORM_CONNECTION=postgres
TYPEORM_HOST=localhost
TYPEORM_USERNAME=myuser
TYPEORM_PASSWORD=mypassword
TYPEORM_DATABASE=mydatabase
TYPEORM_PORT=5432
TYPEORM_SYNCHRONIZE=true
TYPEORM_LOGGING=true
TYPEORM_ENTITIES=src/entity/*.ts

1. Load the .env file at the application entry point:

In your application's entry point, such as index.ts or app.ts, load the .env file using the dotenv library.

typescript
import 'dotenv/config';
// Other application imports and code...

1. Configure TypeORM:

Use environment variables to configure TypeORM. If you are using TypeScript, create a data source instance with these variables, as shown below:

typescript
import { DataSource } from 'typeorm';

const AppDataSource = new DataSource({
    type: process.env.TYPEORM_CONNECTION as any,
    host: process.env.TYPEORM_HOST,
    port: parseInt(process.env.TYPEORM_PORT),
    username: process.env.TYPEORM_USERNAME,
    password: process.env.TYPEORM_PASSWORD,
    database: process.env.TYPEORM_DATABASE,
    synchronize: process.env.TYPEORM_SYNCHRONIZE === 'true',
    logging: process.env.TYPEORM_LOGGING === 'true',
    entities: [process.env.TYPEORM_ENTITIES],
});

export default AppDataSource;

1. Start your application:

When you launch your application, TypeORM will use the settings from the .env file to connect to the database.

Example:

Suppose you have a simple Node.js application using TypeORM to connect to a PostgreSQL database. Here is the .env file:

shell
# .env
TYPEORM_CONNECTION=postgres
TYPEORM_HOST=localhost
TYPEORM_USERNAME=postgres
TYPEORM_PASSWORD=postgres123
TYPEORM_DATABASE=test_db
TYPEORM_PORT=5432
TYPEORM_SYNCHRONIZE=true
TYPEORM_LOGGING=false
TYPEORM_ENTITIES=dist/entity/**/*.js

In index.ts:

typescript
import 'dotenv/config';
import { DataSource } from 'typeorm';
import AppDataSource from './data-source';

AppDataSource.initialize()
    .then(() => {
        // Logic after successful database initialization...
        console.log('Data Source has been initialized!');
    })
    .catch((error) => {
        console.error('Error during Data Source initialization:', error);
    });

This approach allows you to flexibly configure your database connection using environment variables and easily switch configurations across different environments (development, testing, production, etc.).