Running scripts

A seed script is just a .js or .ts file you execute directly — there is nothing special about it. It can call seed(), runSeeders(), or anything else; the name just means "the file responsible for seeding."

Running seed scripts

If you are using ReflectMetadataProvider, reflect-metadata must be the very first import in your seed script — before any entity is loaded. MikroORM's decorators rely on it being in place when the class is evaluated.

import 'reflect-metadata'
import { seed } from '@joakimbugge/mikroorm-seeder'
import { User } from './entities/User.js'

await seed(User).save({ em })

If you are using TsMorphMetadataProvider, no reflect-metadata import is needed.

TypeScript execution

With ReflectMetadataProvider:

# ESM
node --no-warnings --loader ts-node/esm src/seed.ts

# CommonJS
npx ts-node src/seed.ts

ts-node is the right tool here — the popular tsx uses esbuild internally which strips decorator metadata, causing MikroORM to fail.

With TsMorphMetadataProvider:

npx tsx src/seed.ts

Loading seeders from paths

loadSeeders resolves a mixed array of seeder constructors and glob patterns into a flat array of constructors — only classes decorated with @Seeder are collected:

import { loadSeeders, runSeeders } from '@joakimbugge/mikroorm-seeder'

const seeders = await loadSeeders(['dist/seeders/**/*.js'])
await runSeeders(seeders, { em })

Constructor entries are passed through as-is, so you can mix explicit references with glob patterns:

const seeders = await loadSeeders([UserSeeder, 'dist/seeders/Post*.js'])
await runSeeders(seeders, { em })

When running with ts-node or tsx, you can point directly at source files:

const seeders = await loadSeeders(['src/seeders/**/*.ts'])