private async void InitializeHomePage() { var result = await NetworkAPI.GetCompanies(); if (result.Item2 == null) { Companies = new ObservableCollection <Company>(result.Item1); var establishmentList = new List <Establishment>(); foreach (Company c in Companies) { foreach (Establishment e in c.Establishments) { establishmentList.Add(e); } } Establishments = new ObservableCollection <Establishment>(establishmentList); var promotionList = new List <Promotion>(); var eventList = new List <Event>(); foreach (Establishment s in Establishments) { foreach (Promotion p in s.Promotions) { p.Establishment = s; promotionList.Add(p); } foreach (Event e in s.Events) { e.Establishment = s; eventList.Add(e); } } Promotions = new ObservableCollection <Promotion>(promotionList); Events = new ObservableCollection <Event>(eventList); } else { await MessageUtils.ShowDialog("Ophalen gegevens", result.Item2); } }