WsHandlerMetadata

Kind: Interface

Source: packages/websockets/context/ws-context-creator.ts

Part of: Websockets

WsHandlerMetadata describes the reflected metadata required to create and invoke a WebSocket handler. It captures the handler's argument count and parameter types, and provides a module-aware function for retrieving WebSocket parameter metadata.

Properties

Diagram

mermaid
graph LR
  A[WebSocket Gateway Handler] --> B[WsHandlerMetadata]
  B --> C[argsLength: number]
  B --> D[paramtypes: any[]]
  B --> E[getParamsMetadata(moduleKey)]
  E --> F[WsParamProperties[]]
  F --> G[WsContextCreator]

Usage

ts
import type { WsHandlerMetadata } from '@nestjs/websockets';

const handlerMetadata: WsHandlerMetadata = {
  argsLength: 2,
  paramtypes: [Object, Object],
  getParamsMetadata: (moduleKey) => {
    if (moduleKey !== 'chat-module') {
      return [];
    }

    return [
      {
        index: 0,
        data: undefined,
        pipes: [],
        factory: /* WebSocket parameter factory */,
      },
    ];
  },
};

// Pass metadata to the WebSocket context creation flow.
const paramsMetadata = handlerMetadata.getParamsMetadata('chat-module');

AI Coding Instructions

• Preserve argsLength so generated handler argument arrays match the original method signature.
• Keep paramtypes aligned with the reflected parameter types for the gateway handler method.
• Implement getParamsMetadata as module-aware; metadata may differ based on the resolved moduleKey.
• Return an empty WsParamProperties[] when no parameter decorators or metadata apply.
• Integrate this metadata with WsContextCreator when constructing pipes, extracting socket payloads, or resolving decorated parameters.

Relationships

• IMPORTS → CUSTOM_ROUTE_ARGS_METADATA
• IMPORTS → PARAMTYPES_METADATA
• IMPORTS → ContextType
• IMPORTS → Controller
• IMPORTS → PipeTransform
• IMPORTS → isEmpty
• IMPORTS → FORBIDDEN_MESSAGE
• IMPORTS → GuardsConsumer
• IMPORTS → GuardsContextCreator
• IMPORTS → ContextUtils
• IMPORTS → ParamProperties
• IMPORTS → ExecutionContextHost
• IMPORTS → HandlerMetadataStorage
• IMPORTS → ParamsMetadata
• IMPORTS → InterceptorsConsumer
• IMPORTS → InterceptorsContextCreator
• IMPORTS → PipesConsumer
• IMPORTS → PipesContextCreator