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Reputation: 11

extend and implements with super constructor in nest js reposetory interface

I am trying to understand the nest js running project. there is a folder for the repository and in that folder like

db |-- entities (all the tables) |-- interfaces |-- repositories |- base (base repo)

now in the interfaces fonder we have

  extends BaseInterfaceRepository<ClientsEntity>

in the repositories folder, we have

  extends BaseAbstractRepository<ClientsEntity>
  implements ClientsRepositoryInterface
{
  constructor(
    @InjectRepository(ClientsEntity)
    private readonly clientsRepository: Repository<ClientsEntity>,
  ) {
    super(clientsRepository);
  }

I need to understand the flow and structure of the code. especially this part

  extends BaseAbstractRepository<ClientsEntity>
  implements ClientsRepositoryInterface

Upvotes: -1

Views: 23

Answers (1)

RAVI RAJPUT
RAVI RAJPUT

Reputation: 52

BaseAbstractRepository is a generic base class that likely contains common repository logic such as CRUD operations.

ClientsEntity: A generic parameter specifying that this repository will deal with the ClientsEntity.

This documentation can help learn more on generics in typescript

ClientsRepositoryInterface: An interface that defines the contract for this repository, ensuring it implements specific methods required for handling ClientsEntity

This pattern is used in a repository pattern implementation to manage data access for a specific entity, in your case it is the ClientsEntity. It provides an abstraction layer to keeping the business logic separate from data access logic.

Example:

BaseAbstractRepository (Base class)

export abstract class BaseAbstractRepository<T> {
  constructor(protected readonly entity: EntityTarget<T>) {}

  // Generic methods for CRUD operations
  findAll: () => Promise<T[]>;
  findById: (id: number) => Promise<T | undefined>;
  save: (data: T) => Promise<T>;
}

ClientsRepositoryInterface (Interface)

export interface ClientsRepositoryInterface {
  // Entity-specific methods
  findByEmail: (email: string) => Promise<ClientsEntity | undefined>;
  findByName: (name: string) => Promise<ClientsEntity[]>;
}

ClientsEntity (Model for data flow across application)

@Entity('clients')
export class ClientsEntity {
  @PrimaryGeneratedColumn()
  id: number;

  @Column()
  name: string;

  @Column()
  email: string;
}

Benefits of This Pattern

  1. Reusability: Common logic is centralized in the base class.
  2. Flexibility: You can extend or override base methods for specific entities.
  3. Type Safety: Interfaces and generics ensure proper usage and reduce runtime errors.

Upvotes: -1

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