Handling Migrations on NestJS with TypeORM

When facing challenges in managing migrations in NestJS with TypeORM, I realized that the existing documentation did not adequately address this area. Given my recent immersion in NestJS, I decided to share the solution I discovered while researching and resolving these issues.

One of the initial challenges arose when I realized that maintaining the "synchronize" property as true is not a recommended practice for production environments, as it could result in data loss. Consequently, I opted to implement migrations. However, initially, I didn't know how to separate the TypeORM configuration into an independent file and turn it into a data source for the TypeORM CLI to recognize.

PSDT: I'll assume that you're ready create a new nestjs project.

1. TypeORM Configuration in an Independent File

In the file src/db/typeorm.ts, I defined the data source options as follows:

// src/db/typeorm.ts
import { DataSource, DataSourceOptions } from 'typeorm';

export const dataSourceOptions: DataSourceOptions = {
  type: 'postgres',
  host: 'localhost',
  port: 5432,
  username: 'postgres',
  password: 'securepassword',
  database: 'db',
  synchronize: false,
  entities: ['dist/**/*.entity.js'],
  migrationsRun: false,
  migrations: ['dist/db/migrations/*.js'],
};

const AppDataSource = new DataSource(dataSourceOptions);

export default AppDataSource;

2. Integration into the AppModule

Subsequently, in the file app.module.ts, I imported the data source options and incorporated them into the module's configuration:

// app.module.ts
@Module({
  imports: [
    ConfigModule.forRoot(),
    TypeOrmModule.forRoot(dataSourceOptions),
  ],
  controllers: [],
  providers: [],
})
export class AppModule {
  constructor() {}
}

3. Configuration of Scripts in the package.json

Finally, to facilitate the execution of migrations, I added new scripts to the package.json file:

{
  "scripts": {
    "typeorm": "pnpm run build && npx typeorm -d dist/db/typeorm.js",
    "migration:run": "pnpm run typeorm migration:run -- -d dist/db/typeorm.js",
    "migration:generate": "pnpm run typeorm migration:generate",
    "migration:revert": "pnpm run typeorm -- -d ./src/db/typeorm.ts migration:revert"
  }
}

Following these steps, I managed to overcome the issues associated with migrations in NestJS with TypeORM, ensuring a more robust and secure management of the database, especially in production environments. I hope this guide proves helpful in your experience with NestJS and TypeORM.