public SearchRequestsPage(IBusiness business, Frame frame, Host host, ObservableCollection <Unit> ui_units, ObservableCollection <Order> ui_orders) : base(business, frame)
{
InitializeComponent();
DataContext = this;
Host = host;
UiUnits = ui_units;
UiOrders = ui_orders;
Cities.CheckAll(Business.UnitsOf(Host).Select(unit => unit.City).Distinct());
UnitTypes.CheckAll(Business.UnitsOf(Host).Select(unit => unit.UnitType).Distinct());
Amenities.CheckAll(Business.UnitsOf(Host).Aggregate <Unit, IEnumerable <Amenity> >(new HashSet <Amenity>(), (acc, unit) => acc.Union(unit.Amenities)));
}