如何使用MVVM

Question

我有我的WPF應用程序一個gridview的XAML其中看起來像這樣設置的GridView的selectedItems屬性在WPF：

<ListView SelectionMode="Extended" ItemsSource="{Binding AllPartTypes}" 
     local:DataGridService.SelectedItems="{Binding Path=SelectedPartTypes, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"> 
     <ListView.View> 
      <GridView> 
       some columns... 
      </GridView> 
     </ListView.View> 
    </ListView> 

這裏是附加的行爲我使用獲取所選項目：

public static readonly DependencyProperty SelectedItemsProperty = DependencyProperty.RegisterAttached(
      "SelectedItems", 
      typeof(IList), 
      typeof(DataGridService), 
      new UIPropertyMetadata(new List<object>() as IList, OnSelectedItemsChanged)); 

     static SelectionChangedEventHandler GetSelectionChangedHandler(DependencyObject obj) 
     { 
      return (SelectionChangedEventHandler)obj.GetValue(SelectionChangedHandlerProperty); 
     } 
     static void SetSelectionChangedHandler(DependencyObject obj, SelectionChangedEventHandler value) 
     { 
      obj.SetValue(SelectionChangedHandlerProperty, value); 
     } 
     static readonly DependencyProperty SelectionChangedHandlerProperty = 
      DependencyProperty.RegisterAttached("SelectionChangedHandler", typeof(SelectionChangedEventHandler), 
      typeof(DataGridService), new UIPropertyMetadata(null)); 

     //d is MultiSelector (d as ListBox not supported) 
     static void OnSelectedItemsChanged(DependencyObject d, DependencyPropertyChangedEventArgs args) 
     { 
      if (GetSelectionChangedHandler(d) != null) 
       return; 

      if (d is MultiSelector)//DataGrid 
      { 
       MultiSelector multiselector = d as MultiSelector; 
       SelectionChangedEventHandler selectionchanged = null; 
       foreach (var selected in (d as DataGrid).SelectedItems) // GetSelectedItems(d) as IList) 
        multiselector.SelectedItems.Add(selected); 

       selectionchanged = (sender, e) => 
       { 
        SetSelectedItems(d, multiselector.SelectedItems); 
       }; 
       SetSelectionChangedHandler(d, selectionchanged); 
       multiselector.SelectionChanged += GetSelectionChangedHandler(d); 
      } 
      else if (d is ListBox) 
      { 
       ListBox listbox = d as ListBox; 
       SelectionChangedEventHandler selectionchanged = null; 

       selectionchanged = (sender, e) => 
       { 
        SetSelectedItems(d, listbox.SelectedItems); 
       }; 
       SetSelectionChangedHandler(d, selectionchanged); 
       listbox.SelectionChanged += GetSelectionChangedHandler(d); 
      } 
     } 

     public static IList GetSelectedItems(DependencyObject obj) 
     { 
      return (IList)obj.GetValue(SelectedItemsProperty); 
     } 

     public static void SetSelectedItems(DependencyObject obj, IList value) 
     { 
      obj.SetValue(SelectedItemsProperty, value); 
     } 

這適用於在用戶單擊按鈕或某物時獲取viewmodel中的選定項目。我的問題是，當屏幕加載時，我需要突出顯示先前選擇的項目。我沒有成功嘗試在虛擬機的構造函數中設置'SelectedPartTypes'屬性，假設雙向綁定將處理它。有沒有簡單的方法來顯示控件加載時選擇哪些項目？

Answer 1

你不能綁定ListBoxItem樣式中的IsSelected屬性嗎？

<Style TargetType="ListBoxItem"> 
    <Setter Property="IsSelected" Value="{Binding IsSelected}" /> 
</Style> 

如果您的數據對象不具有的屬性來跟蹤選擇，您可能需要使用轉換器返回true，如果當前對象是內SelectedPartTypes