# GrpcService

**Kind:** Constant

**Source:** [`packages/microservices/decorators/grpc-service.decorator.ts`](https://github.com/nestjs/nest/blob/master/packages/microservices/decorators/grpc-service.decorator.ts#L7)

**Part of:** [Microservices](subsystem-packages-microservices)

Defines the GrpcService. The service can inject dependencies through constructor.
Those dependencies have to belong to the same module.

`GrpcService` marks a class as a gRPC service that can be registered and exposed by the microservices layer. The decorated service may receive constructor-injected dependencies, provided those dependencies are registered within the same module.

## Definition

```ts
Controller
```

## Value

```ts
Controller
```

## Diagram

```mermaid
graph LR
  M[Application Module] --> S[@GrpcService class]
  M --> D[Module-scoped Dependency]
  D -->|constructor injection| S
  S --> G[gRPC Server]
  G --> C[gRPC Clients]
```

## Usage

```ts
import { GrpcService } from '@your-package/microservices';

class UserRepository {
  async findById(id: string) {
    return { id, name: 'Ada Lovelace' };
  }
}

@GrpcService()
export class UserGrpcService {
  constructor(private readonly userRepository: UserRepository) {}

  async getUser(request: { id: string }) {
    return this.userRepository.findById(request.id);
  }
}
```

## AI Coding Instructions

- Decorate classes that implement gRPC-facing behavior with `@GrpcService()`.
- Keep constructor dependencies registered in the same module as the gRPC service.
- Prefer injecting domain services or repositories rather than placing business logic directly in transport handlers.
- Do not inject providers from unrelated modules unless they are explicitly made available through the module configuration.
- Ensure gRPC method names and request/response shapes remain aligned with the associated `.proto` contract.

## Relationships

- IMPORTS → `Controller`