getting-started

name	getting-started
description	Use when scanning NestJS providers with DiscoveryService-backed utilities.

@wisemen/nestjs-provider-explorer - Getting Started

Use ProviderExplorerModule when a NestJS package needs to discover all registered class-based providers, then inject ProviderExplorer and filter its providers list with your own decorators or metadata predicates.

Register The Module

Import ProviderExplorerModule anywhere you need provider discovery. The module wraps Nest's DiscoveryModule internally.

import { Module } from '@nestjs/common'
import { ProviderExplorerModule } from '@wisemen/nestjs-provider-explorer'
import { DecoratedProviderRegistry } from './decorated-provider.registry.js'

@Module({
  imports: [ProviderExplorerModule],
  providers: [DecoratedProviderRegistry],
  exports: [DecoratedProviderRegistry]
})
export class DecoratedProviderRegistryModule {}

Explore Registered Providers

Inject ProviderExplorer into a singleton service and iterate over providers during bootstrap or lazy initialization.

import { Injectable, OnApplicationBootstrap } from '@nestjs/common'
import { ProviderExplorer } from '@wisemen/nestjs-provider-explorer'

@Injectable()
export class DecoratedProviderRegistry implements OnApplicationBootstrap {
  constructor (
    private providerExplorer: ProviderExplorer
  ) {}

  onApplicationBootstrap (): void {
    for (const provider of this.providerExplorer.providers) {
      console.info(provider.providerClass.name)
    }
  }
}

The explorer only returns providers that have a class metatype and prototype, which avoids factory-only and value-only registrations.

Filter By Decorator Metadata

The intended pattern is to pair the explorer with custom decorators or metadata guards, then register only the matching providers.

import { Injectable } from '@nestjs/common'
import { ProviderExplorer } from '@wisemen/nestjs-provider-explorer'
import { getQueueName, isQueueHandler } from './queue-handler.decorator.js'

@Injectable()
export class QueueHandlerRegistry {
  constructor (
    private providerExplorer: ProviderExplorer
  ) {}

  build (): Map<string, object> {
    const handlers = new Map<string, object>()

    for (const provider of this.providerExplorer.providers) {
      if (!isQueueHandler(provider.providerClass)) {
        continue
      }

      handlers.set(
        getQueueName(provider.providerClass),
        provider.providerInstance
      )
    }

    return handlers
  }
}

Handle Scoped Providers

Each discovered item includes:

• providerClass: the class metatype
• providerInstance: the instantiated object
• instanceWrapper: Nest's InstanceWrapper

Use providerInstance for singleton providers. When you must support transient or request-scoped providers, inspect instanceWrapper and resolve via ModuleRef instead of caching the instance directly.