RpcExceptionFilter

Kind: Interface

Source: packages/common/interfaces/exceptions/rpc-exception-filter.interface.ts

Part of: Common

Interface describing implementation of an RPC exception filter.

RpcExceptionFilter defines the contract for handling exceptions thrown during RPC and microservice message processing. Implementations receive the thrown exception and execution context, then return an RxJS Observable representing the error response sent through the configured transport.

Diagram

mermaid
graph LR
  A[RPC Request] --> B[Message Handler]
  B -->|Throws exception| C[RpcExceptionFilter]
  C --> D[catch exception, host]
  D --> E[Observable Error Response]
  E --> F[RPC Client / Transport]

Usage

ts
import { ArgumentsHost, Catch, RpcExceptionFilter } from '@nestjs/common';
import { RpcException } from '@nestjs/microservices';
import { Observable, throwError } from 'rxjs';

@Catch(RpcException)
export class RpcErrorFilter
  implements RpcExceptionFilter<RpcException>
{
  catch(exception: RpcException, host: ArgumentsHost): Observable<never> {
    const rpcContext = host.switchToRpc();
    const request = rpcContext.getData();

    console.error('RPC request failed:', request, exception.getError());

    return throwError(() => exception.getError());
  }
}

AI Coding Instructions

• Implement catch(exception, host) and always return an RxJS Observable; use throwError when propagating an RPC error.
• Use host.switchToRpc() to access RPC-specific data, context, or transport arguments instead of HTTP request/response APIs.
• Prefer throwing or handling RpcException instances in microservice handlers so transport-compatible error payloads are preserved.
• Register custom filters through @UseFilters() or as global microservice exception filters, depending on the required scope.
• Avoid returning plain objects or promises directly from catch; the interface expects an observable response.

Used by

2 references from 2 files. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example.

Imported by (2)

• BaseRpcExceptionFilter — packages/microservices/exceptions/base-rpc-exception-filter.ts:15
• ExceptionFilter — sample/03-microservices/src/common/filters/rpc-exception.filter.ts:5