ArgumentsHost

Kind: Interface

Source: packages/common/interfaces/features/arguments-host.interface.ts

Part of: Common

Provides methods for retrieving the arguments being passed to a handler. Allows choosing the appropriate execution context (e.g., Http, RPC, or WebSockets) to retrieve the arguments from.

ArgumentsHost provides access to the arguments supplied when a framework handler is invoked. It lets guards, interceptors, filters, and other framework components inspect the current execution context and switch to the appropriate transport-specific host, such as HTTP, RPC, or WebSockets.

Diagram

mermaid
graph LR
  A[Handler invocation] --> B[ArgumentsHost]
  B --> C[getArgs / getArgByIndex]
  B --> D[switchToHttp]
  B --> E[switchToRpc]
  B --> F[switchToWs]
  D --> G[HTTP request, response, next]
  E --> H[RPC data and context]
  F --> I[WebSocket client and data]

Usage

ts
import {
  ArgumentsHost,
  Catch,
  ExceptionFilter,
  HttpException,
} from '@nestjs/common';

@Catch(HttpException)
export class HttpExceptionFilter implements ExceptionFilter {
  catch(exception: HttpException, host: ArgumentsHost) {
    const http = host.switchToHttp();
    const response = http.getResponse();
    const request = http.getRequest();

    response.status(exception.getStatus()).json({
      statusCode: exception.getStatus(),
      path: request.url,
      message: exception.message,
    });
  }
}

AI Coding Instructions

• Use switchToHttp(), switchToRpc(), or switchToWs() before reading transport-specific arguments.
• Prefer the typed host adapters over accessing raw values through getArgs() or getArgByIndex().
• Keep shared guards, interceptors, and filters transport-aware; not every ArgumentsHost represents an HTTP request.
• Use getType() when behavior must differ between HTTP, RPC, and WebSocket execution contexts.
• Avoid assuming argument positions are consistent across transports; use the relevant context adapter methods instead.

Used by

13 references from 13 files. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example.

Imported by (13)

• UnauthorizedFilter — integration/graphql-code-first/src/common/filters/unauthorized.filter.ts:4
• HttpExceptionFilter — integration/inspector/src/common/filters/http-exception.filter.ts:8
• RequestFilter — integration/websockets/src/request.filter.ts:4
• BaseExceptionFilter — packages/core/exceptions/base-exception-filter.ts:17
• ExceptionsHandler — packages/core/exceptions/exceptions-handler.ts:9
• ExternalExceptionFilter — packages/core/exceptions/external-exception-filter.ts:3
• ExternalExceptionsHandler — packages/core/exceptions/external-exceptions-handler.ts:8
• BaseRpcExceptionFilter — packages/microservices/exceptions/base-rpc-exception-filter.ts:15

…and 5 more.