Custom TypeORM Repositories
Create custom repositories to encapsulate complex database queries and improve code organization and reusability.
Custom TypeORM Repositories is a free NestJS Enterprise Backend APIs lesson on CoddyKit — lesson 1 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the NestJS Enterprise Backend APIs learning path, one of 3 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Beyond Basic CRUD
TypeORM's default Repository offers basic operations like save, find, and delete. These are great for simple tasks.
However, real-world applications often need more complex queries or domain-specific data retrieval logic.
Encapsulating Complex Queries
Without custom repositories, complex database queries might end up directly in your service layer. This can make services bloated and harder to maintain.
- Cleaner Services: Services focus on business logic, not database specifics.
- Reusability: Complex queries can be reused across different parts of your application.
- Testability: Easier to test database interactions in isolation.
Creating a Custom Repository
To create a custom repository, you define a class that extends TypeORM's Repository<Entity>. You must also decorate it with @EntityRepository(Entity) to link it to a specific entity.
import { Entity, PrimaryGeneratedColumn, Column } from 'typeorm';
@Entity()
export class User {
@PrimaryGeneratedColumn()
id: number;
@Column()
name: string;
@Column({ unique: true })
email: string;
@Column({ default: true })
isActive: boolean;
}
// src/user/user.repository.ts
import { EntityRepository, Repository } from 'typeorm';
import { User } from './user.entity';
@EntityRepository(User)
export class UserRepository extends Repository<User> {
// Custom methods will go here
}Injecting the Custom Repository
Once defined, you can inject your custom repository into NestJS services or controllers using the @InjectRepository() decorator.
Remember to pass your custom repository class as an argument to @InjectRepository().
import { Injectable } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { UserRepository } from './user.repository';
import { User } from './user.entity';
@Injectable()
export class UserService {
constructor(
@InjectRepository(UserRepository)
private userRepository: UserRepository,
) {}
async findAllActive(): Promise<User[]> {
// This method will be defined in the custom repo
return this.userRepository.findActiveUsers();
}
}Adding a Custom Method
Inside your custom repository, you can add methods that encapsulate specific query logic. These methods can use the default Repository methods or TypeORM's Query Builder.
Let's add methods to find all active users and find a user by email.
// src/user/user.repository.ts (updated)
import { EntityRepository, Repository } from 'typeorm';
import { User } from './user.entity';
@EntityRepository(User)
export class UserRepository extends Repository<User> {
async findActiveUsers(): Promise<User[]> {
return this.find({ isActive: true });
}
async findByEmail(email: string): Promise<User | undefined> {
return this.findOne({ email });
}
}Custom Repo Workflow
Here's the typical flow: you define your Entity, then your Custom Repository extending Repository<Entity>, and finally inject it into your Service.
// 1. user.entity.ts
import { Entity, PrimaryGeneratedColumn, Column } from 'typeorm';
@Entity() export class User {
@PrimaryGeneratedColumn() id: number;
@Column() name: string;
@Column({ unique: true }) email: string;
@Column({ default: true }) isActive: boolean;
}
// 2. user.repository.ts
import { EntityRepository, Repository } from 'typeorm';
import { User } from './user.entity';
@EntityRepository(User)
export class UserRepository extends Repository<User> {
async findActiveUsers(): Promise<User[]> {
return this.find({ isActive: true });
}
}
// 3. user.service.ts
import { Injectable } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { UserRepository } from './user.repository';
import { User } from './user.entity';
@Injectable()
export class UserService {
constructor(
@InjectRepository(UserRepository)
private userRepository: UserRepository,
) {}
async getAllActive(): Promise<User[]> {
return this.userRepository.findActiveUsers();
}
}Module Configuration
For NestJS to properly manage the TypeORM repositories, your module needs to import TypeOrmModule.forFeature() with your entities. The @EntityRepository decorator handles the TypeORM-side registration, allowing injection.
// src/user/user.module.ts
import { Module } from '@nestjs/common';
import { TypeOrmModule } from '@nestjs/typeorm';
import { User } from './user.entity';
import { UserService } from './user.service';
import { UserController } from './user.controller';
@Module({
imports: [
TypeOrmModule.forFeature([User]) // Only entities here
],
providers: [UserService, UserController],
exports: [UserService] // Export service if used elsewhere
})
export class UserModule {}Leveraging Query Builder
For more complex queries, custom repositories often use TypeORM's powerful Query Builder. This allows you to construct dynamic queries with joins, conditions, and more.
Let's add a method to find users who are active and have a specific name pattern.
// src/user/user.repository.ts (extended)
import { EntityRepository, Repository } from 'typeorm';
import { User } from './user.entity';
import { MoreThan } from 'typeorm'; // Example for complex query
@EntityRepository(User)
export class UserRepository extends Repository<User> {
async findActiveUsers(): Promise<User[]> {
return this.find({ isActive: true });
}
async findByNamePattern(pattern: string): Promise<User[]> {
return this.createQueryBuilder('user')
.where('user.name LIKE :pattern', { pattern: `%${pattern}%` })
.andWhere('user.isActive = :isActive', { isActive: true })
.getMany();
}
}Check Your Understanding
Consider the following custom repository and service:
// product.repository.ts
import { EntityRepository, Repository, MoreThan } from 'typeorm';
import { Product } from './product.entity'; // Assume Product entity exists
@EntityRepository(Product)
export class ProductRepository extends Repository<Product> {
async findAvailableProducts(): Promise<Product[]> {
return this.find({ where: { stock: MoreThan(0), isActive: true } });
}
}
// product.service.ts
import { Injectable } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { ProductRepository } from './product.repository';
import { Product } from './product.entity'; // Assume Product entity exists
@Injectable()
export class ProductService {
constructor(
@InjectRepository(ProductRepository)
private productRepo: ProductRepository,
) {}
async getProducts(): Promise<Product[]> {
return this.productRepo.findAvailableProducts();
}
}Custom Repositories Summary
In this lesson, we explored custom TypeORM repositories. We learned that they are a powerful pattern to:
- Encapsulate complex, reusable database query logic.
- Keep your NestJS services clean and focused on business rules.
- Improve code organization, reusability, and testability.
By extending TypeORM's Repository and using @EntityRepository, you can define domain-specific methods that make your data access layer much more robust.
Frequently asked questions
Is the “Custom TypeORM Repositories” lesson free?
Yes — the full text of “Custom TypeORM Repositories” is free to read here on the web, and the NestJS Enterprise Backend APIs course includes 3 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the NestJS Enterprise Backend APIs course, upgrade to CoddyKit PRO.
What will I learn in “Custom TypeORM Repositories”?
Create custom repositories to encapsulate complex database queries and improve code organization and reusability. You practise NestJS Enterprise Backend APIs with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start NestJS Enterprise Backend APIs?
No prior experience is required. NestJS Enterprise Backend APIs on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 3, so you can start here or from the beginning and move at your own pace.
How long does the “Custom TypeORM Repositories” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this NestJS Enterprise Backend APIs lesson?
Yes. Every NestJS Enterprise Backend APIs lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Custom TypeORM Repositories
- Transactions and Migrations
- Database Seeding and Testing