Generic return type of function in Typescript

Question

I'm new to ts but I've learnt a little about the concept of generics in java. The query is that I have three functions : searchTrack, searchAlbum, searchArtist

  searchTrack(query: string): Observable<Track[]> {
    return this.search(query, 'track');
  }

  searchArtist(query: string): Observable<Artist[]> {
    return this.search(query, 'artist');
  }

  searchAlbum(query: string): Observable<Album[]> {
    return this.search(query, 'album');
  }

I want a general function 'search' in this class that takes the query and the type of entity and returns an Observable of collection of a specific entity type. I'm stuck here. How can I work with generics to specify a generic return type of a function.

search(query: string, type: string): Observable<Array<T>> {
 return this.query(`/search`, [
   `q=${query}`,
   `type=${type}`
 ]);
}

Is there any way I can achieve this?

Answer 1

Try using the Array class instead of []. Also define a generic T type on the search function.

search<T>(query: string, type: string): Observable<Array<T>> {
 return this.query(`/search`, [
   `q=${query}`,
   `type=${type}`
 ]);
}

You should be able to call it like this:

let result = search<Artist>('someQuery', 'artist');

You can find more about generics in typescript in the Generics chapter in the handbook here.