nestjs-request-context

A NestJS module that stores any type of data in the request-scope and makes it accessible from any layer, such as singleton service layers or even repository layers.

Since AsyncLocalStorage is used internally, the required Node.js version is >=14.15.2 that includes significant fixes.

Installation

yarn add '@medibloc/nestjs-request-context'

Usage

There are several ways to enable the request context.

Using middleware in the module

Extend RequestContext to include any data you want.

import { RequestContext } from '@medibloc/nestjs-request-context';

export class MyRequestContext extends RequestContext {
  actor: string;
}

Import RequestContextModule to your AppModule with specifying the context class that you defined above. It automatically registers a middleware that initialize a context for each request (for all route path *).

import { RequestContextModule } from '@medibloc/nestjs-request-context';
import { MyRequestContext } from './my-context.model';

@Module({
  imports: [
    RequestContextModule.forRoot({
      contextClass: MyRequestContext,
      isGlobal: true,
    })
  ]
})
export class AppModule {}

If isGlobal is true, you will not need to import RequestContextModule in other modules once it's been loaded in the root module.

Now, you can access the request context from any Controller/Resolver/Service/Repository layers.

import { RequestContext } from '@medibloc/nestjs-request-context';
import { MyRequestContext } from './my-context.model';

@Controller('')
export class MyController {
  @Get()
  test(): string {
    const ctx: MyRequestContext = RequestContext.get();
    ctx.actor = 'Jack';
    
    return this.myService.test();
  }
}

@Injectable()
export class MyService {
  test(): string {
    const ctx: MyRequestContext = RequestContext.get();
    console.log(`current actor: ${ctx.actor}`);
    
    return ctx.actor;
  }
}

Using functional middleware

If you prefer to use the functional middleware rather than import the module RequestContextModule, you can use the requestContextMiddleware function by passing the context class that you want. In this case, you don't need to import the RequestContextModule to the AppModule.

import { requestContextMiddleware } from '@medibloc/nestjs-request-context';
import { MyRequestContext } from './my-context.model';

const app = await NestFactory(AppModule);
...
app.use(requestContextMiddleware(MyRequestContext));

await app.listen(3000);

Later steps are the same as in the section above.

For GraphQL Subscriptions

If you use GraphQL Subscriptions, the request context middleware will not be executed automatically, because NestJS middlewares are not for Websocket connections.

If you want to initialize the request context for each Websocket connection, please set the onConnect option like below. In this case, you don't need to import the RequestContextModule to the AppModule or use the requestContextMiddleware function.

@Module({
  GraphQLModule.forRoot({
    installSubscriptionHandlers: true,
    subscriptions: {
      onConnect: () => RequestContext.start(PaletteRequestContext),
    },
  }), 
})
export class AppModule{}