@Subscribe Decorator

@Subscribe marks a provider method as a message handler. Handlers are discovered and subscribed automatically on application startup (via DiscoveryModule, imported by the plugin).

Usage

import { Injectable } from '@nestjs/common';
import { Subscribe, IPubSubMessage } from '@nestjs-redisx/pubsub';
import { UserCreatedEvent, NotificationGateway } from './types';

@Injectable()
export class UserEventsHandler {
  constructor(private readonly gateway: NotificationGateway) {}

  // Auto-subscribed on startup via discovery.
  @Subscribe('user.created')
  onUserCreated(message: IPubSubMessage<UserCreatedEvent>): void {
    this.gateway.broadcast('user:new', message.data);
  }

  // Redis glob patterns: *, ?, [..]
  @Subscribe({ pattern: 'order.*' })
  onAnyOrderEvent(message: IPubSubMessage): void {
    // message.pattern === 'order.*', message.channel === concrete channel
    this.gateway.broadcast(message.channel, message.data);
  }
}

Forms

Form	Meaning
@Subscribe('user.created')	Exact channel subscription
@Subscribe({ channel: 'user.created' })	Same, options form
@Subscribe({ pattern: 'user.*' })	PSUBSCRIBE with a Redis glob (*, ?, [..])

Passing both channel and pattern (or neither) throws at decoration time.

The message argument

Handlers receive an IPubSubMessage<T>:

interface IPubSubMessage<T = unknown> {
  channel: string; // logical channel (channelPrefix stripped)
  pattern?: string; // matching pattern (pattern subscriptions only)
  data: T; // JSON-parsed payload (raw string if not JSON)
  raw: string; // payload exactly as received
}

Behaviour

• Handler errors (sync throws and async rejections) are caught and logged — one failing handler never breaks the others or the subscriber connection.
• Multiple decorated methods on any providers may target the same channel; they share one underlying Redis subscription.
• Handlers are bound to their provider instance (this works).