Installation

npm install @nestjs-steroids/async-contextyarn add @nestjs-steroids/async-contextpnpm install @nestjs-steroids/async-context

Usage

import{randomUUID}from'crypto'import{Injectable,NestInterceptor,ExecutionContext,CallHandler}from'@nestjs/common'import{AsyncContext}from'@nestjs-steroids/async-context'import{Observable}from'rxjs'@Injectable()exportclassAsyncContextInterceptorimplementsNestInterceptor{constructor(privatereadonlyac:AsyncContext<string,any>){}intercept(context:ExecutionContext,next:CallHandler):Observable<any>{this.ac.register()// Important to call .register or .registerCallback (good for middleware)this.ac.set('traceId',randomUUID())// Setting default value traceIdreturnnext.handle()}}

import{APP_INTERCEPTOR}from'@nestjs/core';import{Module}from'@nestjs/common';import{AsyncContextModule}from'@nestjs-steroids/async-context';import{AsyncContextInterceptor}from'./async-context.interceptor';@Module({imports:[AsyncContextModule.forRoot()],providers:[{provide:APP_INTERCEPTOR,useClass:AsyncContextInterceptor,},],})exportclassAppModule{}

import{Controller,Get,Logger}from'@nestjs/common'import{AppService}from'./app.service'import{AsyncContext}from'@nestjs-steroids/async-context'@Controller()exportclassAppController{constructor(privatereadonlyappService:AppService,privatereadonlyasyncContext:AsyncContext<string,string>,privatereadonlylogger:Logger){}  @Get()getHello():string{this.logger.log('AppController.getHello',this.asyncContext.get('traceId'))process.nextTick(()=>{this.logger.log('AppController.getHello -> nextTick',this.asyncContext.get('traceId'))setTimeout(()=>{this.logger.log('AppController.getHello -> nextTick -> setTimeout',this.asyncContext.get('traceId'))},0)})returnthis.appService.getHello()}}

Output example

[Nest] 141168  - 02/01/2022, 11:33:11 PM     LOG [NestFactory] Starting Nest application...[Nest] 141168  - 02/01/2022, 11:33:11 PM     LOG [InstanceLoader] AsyncContextModule dependencies initialized +47ms[Nest] 141168  - 02/01/2022, 11:33:11 PM     LOG [InstanceLoader] AppModule dependencies initialized +1ms[Nest] 141168  - 02/01/2022, 11:33:11 PM     LOG [RoutesResolver] AppController {/}: +12ms[Nest] 141168  - 02/01/2022, 11:33:11 PM     LOG [RouterExplorer] Mapped {/, GET} route +7ms[Nest] 141168  - 02/01/2022, 11:33:11 PM     LOG [NestApplication] Nest application successfully started +5ms[Nest] 141168  - 02/01/2022, 11:33:13 PM     LOG [7398d3ad-c246-4650-8dd0-f8f29238bdd7] AppController.getHello[Nest] 141168  - 02/01/2022, 11:33:13 PM     LOG [7398d3ad-c246-4650-8dd0-f8f29238bdd7] AppController.getHello -> nextTick[Nest] 141168  - 02/01/2022, 11:33:13 PM     LOG [7398d3ad-c246-4650-8dd0-f8f29238bdd7] AppController.getHello -> nextTick -> setTimeout

API

AsyncContext almost identical to nativeMap object

classAsyncContext{// Clear all values from storageclear():void;// Delete value by key from storagedelete(key:K):boolean;// Iterate over storageforEach(callbackfn:(value:V,key:K,map:Map<K,V>)=>void,thisArg?:any):void;// Get value from storage by keyget(key:K):V|undefined;// Check if key exists in storagehas(key:K):boolean;// Set value by key in storageset(key:K,value:V): this;// Get number of keys that stored in storagegetsize:number;// Register context, it's better to use this method inside the interceptorregister():void// Register context for a callback, it's better to use this inside the middlewareregisterCallback<R,TArgsextendsany[]>(callback:(...args:TArgs)=>R, ...args:TArgs):R// Unregister contextunregister():void}

AsyncContextModule

interfaceAsyncContextModuleOptions{// Should register this module as global, default: trueisGlobal?:boolean// In case if you need to provide custom value AsyncLocalStoragealsInstance?:AsyncLocalStorage<any>}classAsyncContextModule{staticforRoot(options?:AsyncContextModuleOptions):DynamicModule}

Migration guide from V1

License