CODEWITHSUNDEEP
controlleroverridingnestjsdecorator
superdave
superdave

Reputation: 2298

Is it possible to override the return of a controller method using a NestJS decorator?

I'd like to create an @IgnoreDev decorator that overrides a method return on a NestJS controller when it detects that we're running code in a dev environment.

For example:

@Controller()
class SomeController {

  @IgnoreDev
  async processMessage(...) {
    return 'processed';
  }
}

The @IgnoreDev annotation would detect that process.env.NODE_ENV === 'development' and return ignored instead of processed;

Upvotes: 0

Views: 1233

Answers (1)

Afaq Javed
Afaq Javed

Reputation: 457

I would agree with Mical Levi. You can use Interceptors for overriding the response from the controller.

Create a new file with the name response.override.interceptor.ts Place the following code :

import { Injectable, NestInterceptor, ExecutionContext, CallHandler } from "@nestjs/common";
import { Observable } from "rxjs";
import { tap } from "rxjs/operators";

@Injectable()
export class OverrideResponseInterceptor implements NestInterceptor {
  intercept(context: ExecutionContext, next: CallHandler): Observable<any> {
    return next.handle().pipe(
      map((data) => {
        if (process.env.NODE_ENV === "development") return "ignored ";
        else return "processed";
      })
    );
  }
}

After creating the interceptor you just have to place the @UseInterceptors() decorator (imported from nestjs/common package ) over the controller and pass the recently created interceptor inside the decorator.

@Controller()
class SomeController {

  @UseInterceptors(OverrideResponseInterceptor)
  async processMessage(...) {
    return 'processed';
  }
}

And that's it You can also watch youtube video on interceptors where I gave the detailed Explanation of Interceptors https://youtu.be/v5zvWQagcO0

Extra Tip

Instead of using env variables as process.env.NODE_ENV I would recommend you to use @nestjs/config package which gives extra abstraction over the env variables. If you are interested you can watch the following video https://youtu.be/7OJE4wwZ0R0 You can also read the documentation on env variables at https://docs.nestjs.com/techniques/configuration

Upvotes: 2

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