Typescript - Observable response type change if i call catch

Question

I'm trying to create a service that handle technical errors but i'm facing an issue. The type of the returned item change if i do a catch:

Observable.of(1, 2, 3).subscribe(
  item => {}, // item type is number
  error => {}
);

Observable.of(1, 2, 3).catch(error => {
  // do something
  throw error;
}).subscribe(
  item => {}, // item type is number | {}
  error => {}
);

Is there a way to keep the item type as only a number when catching an observable ?

Context: I'm trying to share the handle of web services throught multiple service:

WepAPI.Service will handle technical error (404, 500, ...)
ComponentRelated.Service will handle functional process and error
Component will handle data transformation specific to the UI

Maybe i'm not doing it the good way, any advice/sample would be aprreciated.

Thank

Flavien Volken · Accepted Answer · 2017-09-28 12:34:00Z

1

Check this

Remember to return an observable from the catch function

Don't throw an error in the error function, the purpose of the .catch is to provide a fallback value without breaking the stream. this fallback must be another observable (while you will still get the content of the observable on the first argument of the subscribe).

Observable.of(1, 2, 3).catch(error => {
  const fallbackValue: number = 42;
  Rx.Observable.of(fallbackValue);
}).subscribe(
  item => {}, // item type is number
  error => {}
);

edited Sep 28, 2017 at 12:34

answered Sep 28, 2017 at 12:28

Flavien Volken

21.5k14 gold badges116 silver badges147 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Typescript - Observable response type change if i call catch

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related