Wanne lifecycle hooks ne NestJS ke ba?

Question

Accepted Answer

NestJS ke ba **lifecycle hooks** — ayyuka da kake aiwatawa don gudnar da code a takaita na musamman a cikin hayafin aikace-aikacen ko mai ba da sabis (kyakkyawa da rufe). Suna da muhimmanci ga shirya (haɗa zuwa albarkatawa) da sai azala (rufe haɗi sosai).

## Gidaje masu mahimmanci

```ts
@Injectable()
export class DatabaseService
  implements OnModuleInit, OnApplicationShutdown {

async onModuleInit() {
    // runs once the host MODULE's dependencies are resolved → do INITIALIZATION
    await this.connect();         // e.g. open a database connection
  }

async onApplicationShutdown(signal: string) {
    // runs when the app is shutting down → do CLEANUP
    await this.disconnect();      // close connections, flush, release resources
  }
}
```

## Jere-jeren hayafin lopin

```text
INITIALIZATION (startup):
  onModuleInit()          → after the module's providers are initialized
  onApplicationBootstrap()→ after ALL modules are initialized (whole app ready)

SHUTDOWN (graceful termination):
  onModuleDestroy()         → cleanup as modules are destroyed
  beforeApplicationShutdown() → before shutdown completes
  onApplicationShutdown(signal) → final shutdown (signal = SIGTERM, etc.)
```

## Wani amfani na gida: sabis na Prisma wanda ke haɗa/ɗan haɗi

```ts
@Injectable()
export class PrismaService extends PrismaClient
  implements OnModuleInit, OnModuleDestroy {

async onModuleInit() {
    await this.$connect();        // connect on startup
  }
  async onModuleDestroy() {
    await this.$disconnect();      // disconnect on shutdown — clean release
  }
}
```

Ganin daidai wannan ne na albarkatawa don albarkatawa da ke bukatar shirya sannu-sannu/sai — haɗa a cikin `onModuleInit`, saki a cikin `onModuleDestroy`.

## Kunna hook-ukan kashe

```ts
// shutdown hooks must be enabled explicitly
const app = await NestFactory.create(AppModule);
app.enableShutdownHooks();        // ❗ required for onApplicationShutdown etc. to fire
```

Hook-ukan kashe ba su guduna ba in ba kun kira `enableShutdownHooks()` ba — sai dadi, sannan azala ba ta guduna ba.

## Me yasa rashin lalata ba ya muhimma

```text
When the app receives SIGTERM (deploy, scale-down, container stop):
  ✗ Without shutdown hooks → connections left open, in-flight work dropped
  ✓ With shutdown hooks → close DB/Redis/queues cleanly, finish work → zero-downtime
```

## Me yasa ya muhimma

Lifecycle hooks suna da mahimmanci don kula da albarkatawa daidai a cikin aikace-aikace NestJS — suna ba da takaita masu dace don yin **kyakkyawa** (bubugar haɗi na jinsi/Redis, jita bayanan, rajista tare da sabis) da, da mahimmanci, **rashin lalata sannu-sannu** a kashe (rufe haɗi, fushi buffers, gama aikin kan jiya).
"];a sanin su shine mahimmanci don amintacciyar masana'antu: **hook-ukan kyakkyawa** (`onModuleInit`, `onApplicationBootstrap`) suna tiyata shirya yana faruwa a lokaci daidai da jiya sa'a haɗi sun shirya, da **hook-ukan kashe** (`onModuleDestroy`, `onApplicationShutdown`) suna kunna **rashin lalata sannu-sannu** — wanda shine mahimmanci a sabon jajjerewa (kwannonin/masu gudanar suna aika SIGTERM akai-akai a lokacin jajjerewa da ƙaryewar awo, da ba tare da sai azala da kyau ba za ku saki haɗi da faɗar bubugan da ke aiki, karwace masana'antu mara saurin kashe).

Gidaje-gidajin daidai na haɗa a cikin `onModuleInit` da ɗan haɗi a cikin `onModuleDestroy` (misali don sabis-sabis na Prisma/jinsi) shine ilimi na kowane rana NestJS, da sanin takaita-taka na bukatar kira `enableShutdownHooks()` (ko hook-ukan kashe a tsinke ba su guduna ba) shine takaita daidai, saukin-saukin samar da kashegari.

Likita lifecycle hooks shine bangare na gina tabba, kasua-karaya NestJS sabis da ke gudanar da albarkatawa da jajjerewa daidai.