How to return custom error in Angular service?

Question

I have a service that will return http query, my caller will by default receive the result and assign it to a News[] object.

 this.service.getNews(url).subscribe((res) => this.news = res);

now I want to throw a custom error if any error occured:

getNews(url:string): Observable<News[]> {
  return this.http.get<News[]>(url).catch(err => {
  throw new Error("My Custom Error");
});

But I got a compling error that "cannot assign the {} to a Observable < News[] >" because the error is not a type of News[].

So how can I modify the code to return an error without changing the returning type Observable < News[] >?

Observable.throw or import _throw: _throw(new Error(...)) — David Pullar
– David Pullar, Commented Aug 29, 2018 at 21:18

Mikhail Burshteyn · Accepted Answer · 2022-10-25 19:39:49Z

3

Instead of throwing your error, try returning an observable of it using Observable.throw.

The docs specifically remind to return an observable from the catch operator.

answered Aug 29, 2018 at 17:51

Mikhail Burshteyn

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