I’m not really sure what you’re asking, but a couple of things that should improve matters:
Please get rid of all the Promise stuff in your provider. Instead simply return the Observables that http gives you, and declare that fact in the method signatures:
export interface AttendanceMedium {
// stuff in here
}
getStudentAttendanceMediumDetails(id: string): Observable<AttendanceMedium[]> {
return this.http.get<AttendanceMedium[]>(this.apiMedium, new HttpParams().set('Id', id));
}
Secondly, it looks like you are trying to populate the options of one select based on a choice made in another. This is harder than it should be, and you might want to see this post.