Convert failing Observable into a good one

Question

I have a call to an HTTP service that return an observable (it's part of a third party library so I cannot change its inner code) and it is throwing an error on the subscribe for a use case that I would like to handle in the happy path.

I have something like this:

My service class:

class MyService {
  getEntities(): Observable<any> {
    return this.http.get('<the url'>)
      .pipe(
        catchError(err => {
          // Handle the errors and returns a string corresponding to each message.
          // Here I show an example with the status code 403
          if (err.status === 403) {
            return throwError('My error message for 403');
          }

          // This is what I want to do.
          if (err.status === 409) {
            // Somehow, make this to trigger the goodResponse in the consumer class.
          }
        })
      );
  }
}

My consumer:

class MyComponent {
  private myService: MyService;

  constructor() {
    this.myService = new MyService();
  }

  callTheAPI() {
    this.myService.getEntities()
      .subscribe(goodResponse => {
        // Handle good response
      }, error => {
        // Handle error
      });
  }
}

So, for the current code example, what I want to do is, for the case where the status code is 409, make the subscription to succeed.

Answer 1

Then just return a new Observable (that sends next item). throwError sends only the error notification so you can use of():

import { of } from 'rxjs';

...

catchError(err => {
    // Handle the errors and returns a string corresponding to each message.
    // Here I show an example with the status code 403
    if (err.status === 403) {
        return throwError('My error message for 403');
    }

    // This is what I want to do.
    if (err.status === 409) {
        return of(/* fake response goes here */)
    }
})