How to extend TypeORM repository in NestJS 9 (TypeORM 3.+)

Question

Previously, TypeORM repository could be extended and injected directly into services, e.g.:

import { User } from './entities/user.entity';
import { EntityRepository, Repository } from 'typeorm';

@EntityRepository(User)
export class UsersRepo extends Repository<User> {
  // my custom repo methods
}

import { Injectable } from '@nestjs/common'
import { UsersRepo } from './users.repo';

@Injectable()
export class UsersService {
  constructor(private readonly usersRepo: UsersRepo) {}
}

But since version 3.0.0 TypeORM does not support repository extending via inheritance.

How to achieve such behavior in NestJS 9 (which depends on TypeORM 3.+)? The only solution I came up with is to add custom methods to the service layer. But I would like to keep all ORM-related methods (query, aggregations, etc.) in the repository layer.

Answer 1

Let me tell you straight away: I have no idea whether this is a recommended solution, I don't know if the authors of TypeORM actually considered such approach at all. But what I just did a minute ago is this:

@Injectable()
export class UserRepository extends Repository<UserEntity> {


  constructor(
    @InjectRepository(UserEntity)
    repository: Repository<UserEntity>
  ) {
    super(repository.target, repository.manager, repository.queryRunner);
  }
}

And the best part: it worked :D

I use: "@nestjs/typeorm": "^9.0.0" just so you know.

I will keep checking if it doesn't break anything, but for now, seems like a good workaround.

Answer 2

Hope helpful for you:

---

import { DataSource, Repository } from 'typeorm';
import { EntityTarget } from 'typeorm/common/EntityTarget';

export class GenericRepository<T> extends Repository<T> {
  constructor(target: EntityTarget<T>, dataSource: DataSource) {
    super(target, dataSource.createEntityManager());
  }

  async someCommonMethod() {
    return {};
  }
}

---

import { DataSource } from 'typeorm';
import { User } from '../../entities/User';
import { Injectable } from '@nestjs/common';
import { GenericRepository } from '../common/generic.repository';

@Injectable()
export class UserRepository extends GenericRepository<User> {
  constructor(private dataSource: DataSource) {
    super(User, dataSource.createEntityManager());
  }
}

---

import { Injectable } from '@nestjs/common';
import { User } from '../../entities/User';
import { InjectRepository } from '@nestjs/typeorm';
import { UsersRepository } from './users.repository';


@Injectable()
export class UsersService {
  constructor(
    @InjectRepository(User)
    private readonly usersRepository: UsersRepository,
  ) {}
}