protected override void OnInitialized(EventArgs e) { var provider = new CatalogProvider(); var types = provider.GetCatalogTypes(); types.Insert(0, new CatalogTypeModel()); Types = new ObservableCollection <CatalogTypeModel>(types); var brands = provider.GetCatalogBrands(); brands.Insert(0, new CatalogBrandModel()); Brands = new ObservableCollection <CatalogBrandModel>(brands); UpdateItemList(); base.OnInitialized(e); }