DataGrid - 摺疊除第一個以外的所有組

Question

我有一個DataGrid與分組的ItemsSource。每個組都有一個擴展器，因此我可以展開/摺疊所有組。現在，我試圖在默認情況下摺疊所有組，但是保留第一組。項目源是動態的，所以我不能建立任何轉換器來檢查組名。我必須通過小組索引來完成。

在XAML中可以做到嗎？或在代碼隱藏？

請幫忙。

Answer 1

我不相信它可以在XAML中完成，但它可以在代碼隱藏中完成。這是我在Silverlight中測試的一個解決方案。它應該可以在WPF中工作。

// If you don't have a direct reference to the grid's ItemsSource, 
// then cast the grid's ItemSource to the type of the source. 
// In this example, I used a PagedCollectionView for the source. 
PagedCollectionView pcv = (PagedCollectionView)myDataGrid.ItemsSource; 

// Using the PagedCollectionView, I can get a reference to the first group. 
CollectionViewGroup firstGroup = (CollectionViewGroup)pcv.Groups[0]; 

// First collapse all groups (if they aren't already collapsed). 
foreach (CollectionViewGroup group in pcv.Groups) 
{ 
    myDataGrid.ScrollIntoView(group, null); // This line is a workaround for a problem with collapsing groups when they aren't visible. 
    myDataGrid.CollapseRowGroup(group, true); 
} 

// Now expand only the first group. 
// If using multiple levels of grouping, setting 2nd parameter to "true" will expand all subgroups under the first group. 
myDataGrid.ExpandRowGroup(firstGroup, false); 

// Scroll to the top, ready for the user to see! 
myDataGrid.ScrollIntoView(firstGroup, null); 

Answer 2

這可能是有點晚了，但爲了幫助類似的問題，確定了「視覺樹的輔助類」會在這種情況下有幫助。

// the visual tree helper class 
public static class VisualTreeHelper 
{ 
    public static Collection<T> GetVisualChildren<T>(DependencyObject current) where T : DependencyObject 
    { 
     if (current == null) 
      return null; 

     var children = new Collection<T>(); 
     GetVisualChildren(current, children); 
     return children; 
    } 
    private static void GetVisualChildren<T>(DependencyObject current, Collection<T> children) where T : DependencyObject 
    { 
     if (current != null) 
     { 
      if (current.GetType() == typeof(T)) 
       children.Add((T)current); 

      for (int i = 0; i < System.Windows.Media.VisualTreeHelper.GetChildrenCount(current); i++) 
      { 
       GetVisualChildren(System.Windows.Media.VisualTreeHelper.GetChild(current, i), children); 
      } 
     } 
    } 
} 

// then you can use the above class like this: 
Collection<Expander> collection = VisualTreeHelper.GetVisualChildren<Expander>(dataGrid1); 

    foreach (Expander expander in collection) 
     expander.IsExpanded = false; 

collection[0].IsExpanded = true; 

要歸功於this forum

Answer 3

我能在我的視圖模型來解決這個問題。
Expander在DataGrids GroupStyle的模板中定義。綁定必須是雙向的，但是明確觸發，因此在視圖中單擊不會更新ViewModel。謝謝Rachel。

<Expander IsExpanded="{Binding DataContext.AreAllGroupsExpanded, RelativeSource={RelativeSource AncestorType={x:Type local:MyControl}}, UpdateSourceTrigger=Explicit}"> 
    ... 
</Expander> 

然後我可以在我的ViewModel中設置屬性AreAllGroupsExpanded。