RedisContext

Kind: Class

Source: packages/microservices/ctx-host/redis.context.ts

Part of: Microservices

RedisContext provides Redis-specific metadata to microservice message handlers. It wraps the incoming Redis message context and exposes the channel name through getChannel(), allowing handlers to identify the source channel.

Extends: BaseRpcContext

Methods

Diagram

mermaid
graph LR
  Redis[Redis Pub/Sub Channel] --> Server[Redis Transport Server]
  Server --> Context[RedisContext]
  Context --> Handler[Message Handler]
  Handler --> Channel[getChannel()]

Usage

ts
import { Controller } from '@nestjs/common';
import { Ctx, MessagePattern, RedisContext } from '@nestjs/microservices';

@Controller()
export class NotificationsController {
  @MessagePattern('notifications.*')
  handleNotification(
    payload: { message: string },
    @Ctx() context: RedisContext,
  ) {
    const channel = context.getChannel();

    console.log(`Received "${payload.message}" from ${channel}`);

    return { received: true, channel };
  }
}

AI Coding Instructions

• Use RedisContext only in handlers executed through the Redis microservice transport.
• Retrieve the originating Redis channel with context.getChannel() rather than relying on a hard-coded channel name.
• Inject the context with @Ctx() alongside payload parameters in @MessagePattern() handlers.
• Treat the channel value as transport metadata; keep business logic independent of Redis-specific context where possible.

How it works

RedisContext is an exported RPC context class for Redis message handling. It extends BaseRpcContext with a one-element argument tuple whose item is a string. redis.context.ts:3-10

• Construction: new RedisContext(args) accepts the [string] tuple and passes that same tuple to the base-class constructor, which stores it as protected, read-only args. redis.context.ts:3-10 base-rpc.context.ts:4-5
• getChannel() returns the tuple’s first item (args[0]); the class documentation identifies this value as the channel name. redis.context.ts:13-18
• Inherited accessors: getArgs() returns the stored tuple, and getArgByIndex(index) returns the item at the requested index. base-rpc.context.ts:7-20
• Server construction: ServerRedis creates this context as new RedisContext([pattern]) while handling an incoming message. Without wildcard mode, it passes the received channel as pattern; with wildcard mode, it passes the callback’s pattern argument. server-redis.ts:126-142 The resulting context is passed to event handling, request handlers, and processing hooks. server-redis.ts:144-172
• Validation, errors, and side effects: Neither the constructor nor getChannel() performs runtime validation, throws an error, or mutates external state in the visible code; they store and read the argument tuple. redis.context.ts:8-18 base-rpc.context.ts:4-5