@Dedupe

Proxy-based decorator (same mechanism as @WithLock): works on any @Injectable method.

import { Injectable } from '@nestjs/common';
import { Dedupe } from '@nestjs-redisx/dedup';
import { StripeEvent } from './types';

@Injectable()
export class WebhookService {
  // Providers redeliver: each event id is handled once per 5 minutes,
  // fleet-wide. Duplicate deliveries resolve to undefined without running
  // the body. A THROWN first attempt releases the marker, so the provider's
  // retry is not locked out for the rest of the window.
  @Dedupe({ key: 'stripe:{0}', window: 300_000 })
  async handleStripeEvent(eventId: string, event: StripeEvent): Promise<void> {
    // ...apply the event exactly once per window...
  }
}

Options

Option	Type	Description
key	string | (...args) => string	Dedup key; {n} interpolates the n-th argument
window	number?	Window in ms (default: plugin defaultWindow)

Semantics

• The first call (per key, across all instances) runs the body and returns its result; repeats within the window resolve undefined without running it.
• A thrown body releases this caller's marker - the retry is not locked out for the rest of the window.
• Store unavailability follows the plugin errorPolicy.

Composing with @Cron

Both orders are safe - the wrapper carries over metadata stamped by decorators below it, so @Dedupe() above @Cron() does not unregister the job.

Without the Plugin

If DedupPlugin is not registered, the method executes without deduplication and logs a warning - fail-open: a possible duplicate is recoverable, a silently skipped business method is not.

Return Type Caveat

Callers of a deduplicated method must accept undefined (the duplicate outcome). If every caller needs the value, deduplicate at the event boundary (the webhook controller) rather than deep in the call chain.