feat(core): add EntityRepositoryType symbol (#698)

This allows to pass the type of your custom repository in the entity definition,
which will be then used in `em.getRepository(Entity)`.

```typescript
@entity({ customRepository: () => AuthorRepository })
export class Author {

  [EntityRepositoryType]?: AuthorRepository;

}

const repo = em.getRepository(Author); // repo has type AuthorRepository
```

Related: #696

packages/core/src/EntityManager.ts

@@ -5,7 +5,7 @@ import { Configuration, QueryHelper, RequestContext, Utils, ValidationError } fr
 import { EntityAssigner, EntityFactory, EntityLoader, EntityRepository, EntityValidator, IdentifiedReference, LoadStrategy, Reference, ReferenceType, wrap } from './entity';
 import { LockMode, UnitOfWork } from './unit-of-work';
 import { CountOptions, DeleteOptions, EntityManagerType, FindOneOptions, FindOneOrFailOptions, FindOptions, IDatabaseDriver, UpdateOptions } from './drivers';
-import { AnyEntity, Dictionary, EntityData, EntityMetadata, EntityName, FilterDef, FilterQuery, Loaded, Primary, Populate, PopulateMap, PopulateOptions, New } from './typings';
+import { AnyEntity, Dictionary, EntityData, EntityMetadata, EntityName, FilterDef, FilterQuery, Loaded, Primary, Populate, PopulateMap, PopulateOptions, New, GetRepository } from './typings';
 import { QueryOrderMap } from './enums';
 import { MetadataStorage } from './metadata';
 import { Transaction } from './connections';
@@ -50,7 +50,7 @@ export class EntityManager<D extends IDatabaseDriver = IDatabaseDriver> {
   /**
    * Gets repository for given entity. You can pass either string name or entity class reference.
    */
-  getRepository<T extends AnyEntity<T>, U extends EntityRepository<T> = EntityRepository<T>>(entityName: EntityName<T>): U {
+  getRepository<T extends AnyEntity<T>, U extends EntityRepository<T> = EntityRepository<T>>(entityName: EntityName<T>): GetRepository<T, U> {
     entityName = Utils.className(entityName);
 
     if (!this.repositoryMap[entityName]) {
@@ -59,7 +59,7 @@ export class EntityManager<D extends IDatabaseDriver = IDatabaseDriver> {
       this.repositoryMap[entityName] = new RepositoryClass(this, entityName);
     }
 
-    return this.repositoryMap[entityName] as unknown as U;
+    return this.repositoryMap[entityName] as unknown as GetRepository<T, U>;
   }
 
   /**

packages/core/src/index.ts

@@ -2,6 +2,7 @@
 export {
   Constructor, Dictionary, PrimaryKeyType, Primary, IPrimaryKey, FilterQuery, IWrappedEntity, EntityName, EntityData,
   AnyEntity, EntityProperty, EntityMetadata, QBFilterQuery, PopulateOptions, Populate, Loaded, New, LoadedReference, LoadedCollection,
+  GetRepository, EntityRepositoryType,
 } from './typings';
 export * from './enums';
 export * from './exceptions';

packages/core/src/typings.ts

@@ -25,6 +25,7 @@ export type DeepPartialEntity<T> = {
         : DeepPartialEntity<T[P]> | PartialEntity<T[P]> | Primary<T[P]> | OperatorMap<T[P]> | StringProp<T[P]>)
 };
 
+export const EntityRepositoryType = Symbol('EntityRepositoryType');
 export const PrimaryKeyType = Symbol('PrimaryKeyType');
 export type Primary<T> = T extends { [PrimaryKeyType]: infer PK }
   ? PK : T extends { _id: infer PK }
@@ -101,12 +102,13 @@ export interface IWrappedEntityInternal<T, PK extends keyof T, P = keyof T> exte
   __serializedPrimaryKey: string & keyof T;
 }
 
-export type AnyEntity<T = any> = { [K in keyof T]?: T[K] } & { [PrimaryKeyType]?: unknown };
+export type AnyEntity<T = any> = { [K in keyof T]?: T[K] } & { [PrimaryKeyType]?: unknown; [EntityRepositoryType]?: unknown };
 // eslint-disable-next-line @typescript-eslint/ban-types
 export type EntityClass<T extends AnyEntity<T>> = Function & { prototype: T };
 export type EntityClassGroup<T extends AnyEntity<T>> = { entity: EntityClass<T>; schema: EntityMetadata<T> | EntitySchema<T> };
 export type EntityName<T extends AnyEntity<T>> = string | EntityClass<T> | EntitySchema<T, any>;
 export type EntityData<T extends AnyEntity<T>, P extends Populate<T> = keyof T> = { [K in keyof T]?: T[K] | Primary<T[K]> | EntityData<T[K]> | CollectionItem<T[K]>[] } & Dictionary;
+export type GetRepository<T extends AnyEntity<T>, U> = T[typeof EntityRepositoryType] extends EntityRepository<any> | undefined ? NonNullable<T[typeof EntityRepositoryType]> : U;
 
 export interface EntityProperty<T extends AnyEntity<T> = any> {
   name: string & keyof T;

packages/knex/src/SqlEntityManager.ts

@@ -1,5 +1,5 @@
 import Knex, { QueryBuilder as KnexQueryBuilder, Raw } from 'knex';
-import { AnyEntity, EntityData, EntityManager, EntityName, EntityRepository, QueryResult, Utils } from '@mikro-orm/core';
+import { AnyEntity, EntityData, EntityManager, EntityName, EntityRepository, GetRepository, QueryResult, Utils } from '@mikro-orm/core';
 import { AbstractSqlDriver } from './AbstractSqlDriver';
 import { QueryBuilder } from './query';
 import { SqlEntityRepository } from './SqlEntityRepository';
@@ -25,7 +25,7 @@ export class SqlEntityManager<D extends AbstractSqlDriver = AbstractSqlDriver> e
     return this.getDriver().execute(queryOrKnex, params, method, this.getTransactionContext());
   }
 
-  getRepository<T extends AnyEntity<T>, U extends EntityRepository<T> = SqlEntityRepository<T>>(entityName: EntityName<T>): U {
+  getRepository<T extends AnyEntity<T>, U extends EntityRepository<T> = SqlEntityRepository<T>>(entityName: EntityName<T>): GetRepository<T, U> {
     return super.getRepository<T, U>(entityName);
   }
 

packages/mongodb/src/MongoEntityManager.ts

@@ -1,4 +1,4 @@
-import { AnyEntity, EntityManager, EntityName, EntityRepository, Utils } from '@mikro-orm/core';
+import { AnyEntity, EntityManager, EntityName, EntityRepository, GetRepository, Utils } from '@mikro-orm/core';
 import { MongoDriver } from './MongoDriver';
 import { MongoEntityRepository } from './MongoEntityRepository';
 import { Collection } from 'mongodb';
@@ -20,7 +20,7 @@ export class MongoEntityManager<D extends MongoDriver = MongoDriver> extends Ent
     return this.getConnection().getCollection(entityName);
   }
 
-  getRepository<T extends AnyEntity<T>, U extends EntityRepository<T> = MongoEntityRepository<T>>(entityName: EntityName<T>): U {
+  getRepository<T extends AnyEntity<T>, U extends EntityRepository<T> = MongoEntityRepository<T>>(entityName: EntityName<T>): GetRepository<T, U> {
     return super.getRepository<T, U>(entityName);
   }
 

tests/EntityManager.mongo.test.ts

@@ -160,7 +160,7 @@ describe('EntityManagerMongo', () => {
   });
 
   test('should provide custom repository', async () => {
-    const repo = orm.em.getRepository(Author) as AuthorRepository;
+    const repo = orm.em.getRepository(Author);
     expect(repo).toBeInstanceOf(AuthorRepository);
     expect(repo.magic).toBeInstanceOf(Function);
     expect(repo.magic('test')).toBe('111 test 222');
@@ -256,7 +256,7 @@ describe('EntityManagerMongo', () => {
   });
 
   test('findOne should work with options parameter', async () => {
-    const repo = orm.em.getRepository(Author) as AuthorRepository;
+    const repo = orm.em.getRepository(Author);
     const author = new Author('name 1', 'email1');
     const author2 = new Author('name 2', 'email2');
     await repo.persistAndFlush([author, author2]);
@@ -282,7 +282,7 @@ describe('EntityManagerMongo', () => {
   });
 
   test('should convert entity to PK when trying to search by entity', async () => {
-    const repo = orm.em.getRepository(Author) as AuthorRepository;
+    const repo = orm.em.getRepository(Author);
     const author = new Author('name', 'email');
     author.favouriteAuthor = author;
     await repo.persistAndFlush(author);
@@ -296,7 +296,7 @@ describe('EntityManagerMongo', () => {
     const author = new Author('name', 'email');
     const author2 = new Author('name2', 'email2');
     const author3 = new Author('name3', 'email3');
-    const repo = orm.em.getRepository(Author) as AuthorRepository;
+    const repo = orm.em.getRepository(Author);
     repo.persist(author);
     repo.persist(author2);
     await repo.removeAndFlush(author);
@@ -309,7 +309,7 @@ describe('EntityManagerMongo', () => {
 
   test('removing persisted entity will remove it from persist stack first', async () => {
     const author = new Author('name', 'email');
-    const repo = orm.em.getRepository(Author) as AuthorRepository;
+    const repo = orm.em.getRepository(Author);
     await repo.persistAndFlush(author);
     expect(orm.em.getUnitOfWork().getById<Author>(Author.name, author.id)).toBeDefined();
     author.name = 'new name';
@@ -321,7 +321,7 @@ describe('EntityManagerMongo', () => {
 
   test('removing persisted entity via PK', async () => {
     const author = new Author('name', 'email');
-    const repo = orm.em.getRepository(Author) as AuthorRepository;
+    const repo = orm.em.getRepository(Author);
     await repo.persistAndFlush(author);
     orm.em.clear();
 

tests/entities/Author.ts

@@ -1,6 +1,6 @@
 import {
   AfterCreate, AfterDelete, AfterUpdate, BeforeCreate, BeforeDelete, BeforeUpdate, DateType, Collection,
-  Cascade, Entity, ManyToMany, ManyToOne, OneToMany, Property, Index, Unique, EntityAssigner,
+  Cascade, Entity, ManyToMany, ManyToOne, OneToMany, Property, Index, Unique, EntityAssigner, EntityRepositoryType,
 } from '@mikro-orm/core';
 
 import { Book } from './Book';
@@ -11,6 +11,8 @@ import { BaseEntity } from './BaseEntity';
 @Index({ name: 'custom_idx_1', properties: ['name', 'email'] })
 export class Author extends BaseEntity<Author> {
 
+  [EntityRepositoryType]: AuthorRepository;
+
   static beforeDestroyCalled = 0;
   static afterDestroyCalled = 0;