WsArgumentsHost

Kind: Interface

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

Part of: Common

Methods to obtain WebSocket data and client objects.

WsArgumentsHost provides typed access to the arguments associated with a WebSocket handler invocation. It exposes the incoming message payload, connected client instance, and event pattern after an ArgumentsHost or ExecutionContext has been switched to the WebSocket context.

Diagram

mermaid
graph LR
  A[WebSocket Event] --> B[ExecutionContext]
  B --> C[switchToWs()]
  C --> D[WsArgumentsHost]
  D --> E[getClient()]
  D --> F[getData()]
  D --> G[getPattern()]

Usage

ts
import {
  CallHandler,
  ExecutionContext,
  Injectable,
  NestInterceptor,
  WsArgumentsHost,
} from '@nestjs/common';
import { Observable } from 'rxjs';
import { Socket } from 'socket.io';

@Injectable()
export class WsLoggingInterceptor implements NestInterceptor {
  intercept(context: ExecutionContext, next: CallHandler): Observable<unknown> {
    const wsContext: WsArgumentsHost = context.switchToWs();

    const client = wsContext.getClient<Socket>();
    const data = wsContext.getData<{ message: string }>();
    const pattern = wsContext.getPattern();

    console.log({
      clientId: client.id,
      pattern,
      message: data.message,
    });

    return next.handle();
  }
}

AI Coding Instructions

• Obtain this interface through context.switchToWs() when working in guards, interceptors, filters, or pipes that support multiple transport types.
• Use generic type parameters with getData<T>() and getClient<T>() to avoid untyped message payloads and client objects.
• Do not assume the client is always a Socket.IO Socket; its type depends on the configured WebSocket adapter.
• Use getPattern() when logging, authorizing, or routing behavior based on the WebSocket event name.

Used by

1 reference from 1 file. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example.

Imported by (1)

• ExecutionContextHost — packages/core/helpers/execution-context-host.ts:10