# GrpcMethod

**Kind:** Function

**Source:** [`packages/microservices/decorators/message-pattern.decorator.ts`](https://github.com/nestjs/nest/blob/master/packages/microservices/decorators/message-pattern.decorator.ts#L104)

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

`GrpcMethod()` marks a controller method as a handler for a gRPC service RPC. It stores the service and method metadata used by the microservice transport to route incoming gRPC requests to the decorated method.

## Signature

```ts
function GrpcMethod(service: string | undefined, method: string): MethodDecorator
```

## Parameters

| Name | Type |
|---|---|
| `service` | `string | undefined` |
| `method` | `string` |

**Returns:** `MethodDecorator`

## Diagram

```mermaid
graph LR
  Client[gRPC Client] --> Server[gRPC Microservice Server]
  Server --> Service[Proto Service and RPC]
  Service --> Decorator["@GrpcMethod('UsersService', 'FindOne')"]
  Decorator --> Handler[Controller Handler Method]
  Handler --> Response[gRPC Response]
```

## Usage

```ts
import { Controller } from '@nestjs/common';
import { GrpcMethod } from '@nestjs/microservices';

interface FindUserRequest {
  id: string;
}

interface User {
  id: string;
  name: string;
}

@Controller()
export class UsersController {
  @GrpcMethod('UsersService', 'FindOne')
  findOne(request: FindUserRequest): User {
    return {
      id: request.id,
      name: 'Ada Lovelace',
    };
  }
}
```

## AI Coding Instructions

- Match the `service` and RPC method names with the definitions in the loaded `.proto` file.
- Decorate methods in a controller that is registered with the gRPC microservice module.
- Keep handler request and response shapes compatible with the generated protobuf contract.
- Use the explicit method argument when the TypeScript method name differs from the proto RPC name.
- Do not use this decorator for HTTP routes; use it only for handlers served by a gRPC transport.