npm install @mikro-orm/migrations-mongodb

# Create a blank migration
npx mikro-orm migration:create --blank

# Run pending migrations
npx mikro-orm migration:up

# Revert the last migration
npx mikro-orm migration:down

import { MikroORM } from '@mikro-orm/mongodb';

const orm = await MikroORM.init({
  entities: [Author, Book],
  dbName: 'my-db',
  clientUrl: 'mongodb://localhost:27017',
  migrations: {
    path: './src/migrations',
  },
});

const migrator = orm.migrator;
await migrator.up();

import { Migration } from '@mikro-orm/migrations-mongodb';

export class Migration20250101 extends Migration {
  async up(): Promise<void> {
    const collection = this.getCollection('users');
    await collection.updateMany({}, { $set: { active: true } });
  }

  async down(): Promise<void> {
    const collection = this.getCollection('users');
    await collection.updateMany({}, { $unset: { active: '' } });
  }
}