Type inference with generic custom repository

[krishnabrq]

I am following documentation to add a generic custom repository to my MikroORM configuration. It appears that the type inference is not working in this case. Below is a small repro for the issue I am facing -

import {
  defineConfig,
  defineEntity,
  EntityRepository,
  MikroORM,
  p,
  type InferEntity,
} from '@mikro-orm/postgresql';

class BaseRepository<Entity extends object> extends EntityRepository<Entity> {
  exists() {
    // implementation here
    return (Math.random() * 10) % 2;
  }
}

const User = defineEntity({
  name: 'User',
  tableName: 'users',
  properties: {
    id: p.uuid().primary(),
    email: p.string(),
  },
});

type User = InferEntity<typeof User>;

const config = defineConfig({
  dbName: 'repro',
  entities: [User],
  entityRepository: () => BaseRepository,
});

async function main() {
  const orm = await MikroORM.init(config);

  const repo = orm.em.getRepository(User);

  await repo.findAll();

  // Expected: global `entityRepository` should make this available.
  // Actual: TS error - Property 'exists' does not exist on type ...
  await repo.exists();
}

void main();

I am using -

"@mikro-orm/core": "^7.0.5"
"@mikro-orm/postgresql": "^7.0.5"
"typescript": "^6.0.2"

I will be very helpful if someone points out the correct way of doing it.

[B4nan]

ORM config is not relevant on type level, you need to specify the repository in your entity definition, that's what add the type level hint. For a generic base repository, it would make sense to define a base entity that does this. The section above the one you mentioned shows how.

edit: I'll adjust the docs about this

[krishnabrq]

Thanks @B4nan

[sueun-dev]

The global entityRepository in defineConfig is a runtime-only setting — it tells MikroORM which class to instantiate, but TypeScript doesn't use it for type inference. So getRepository(User) still returns EntityRepository<User> at the type level regardless of what's set there.

To get BaseRepository<User> back from getRepository, specify the repository directly in the entity definition:

const User = defineEntity({
  name: 'User',
  tableName: 'users',
  repository: () => BaseRepository, // add this
  properties: {
    id: p.uuid().primary(),
    email: p.string(),
  },
});

With that change, orm.em.getRepository(User) is typed as BaseRepository<User>, so repo.exists() resolves correctly.

You can still keep entityRepository: () => BaseRepository in defineConfig as a runtime fallback for entities that don't declare their own, but the type-level inference only kicks in when repository is declared on the entity itself.

For reference, if you're using the decorator-based entity style the equivalent looks like this:

@Entity({ repository: () => BaseRepository })
class User {
  [EntityRepositoryType]?: BaseRepository<User>; // manual type hint needed for decorators
  // ...
}

The defineEntity API skips the [EntityRepositoryType] symbol — declaring repository in the options is enough for the types to flow through.

[B4nan]

Fixed the docs via #7428