wpf datagrid icollectionview排序BUG？ [英] wpf datagrid icollectionview sorting BUG?

问题描述

有人可以帮助我吗？我有以下情况：

1. 一个简单的视图：

    < Window x：Class =DataGridSortBug.MainWindow
    xmlns =http://schemas.microsoft.com/winfx/2006/xaml/presentation
    xmlns：x =http://schemas.microsoft.com/winfx/2006/xaml
    Title =MainWindowHeight =350Width =525> 
   & DockPanel> 
   < StackPanel DockPanel.Dock =Top> 
   < Button Click =Button_Click>刷新< / Button> 
   < / StackPanel> 
    
   < DataGrid ItemsSource ={Binding View}/> 
   < / DockPanel> 
   < / Window> 
     




2. 代码背后：

     public partial class MainWindow：Window 
    {
    public MainWindow（）
    {
    InitializeComponent（）; 
    
    DataContext = new ViewModel（）; 
   } 
    
    public class TestItem 
    {
    private int _sequence; 
    public int Sequence 
    {
    get {return _sequence; 
   } 
    
    public TestItem（int sequence）
    {
    _sequence = sequence; 
   } 
   } 
    
    public class ViewModel 
    {
    ObservableCollection< TestItem> _采集; 
    
   私人ICollectionView _view; 
    public ICollectionView View 
    {
    get {return _view; } 
   } 
    
    public ViewModel（）
    {
    _collection = new ObservableCollection< TestItem>（）; 
    _collection.Add（new TestItem（5））; 
    _collection.Add（new TestItem（2））; 
    _collection.Add（new TestItem（4））; 
    _collection.Add（new TestItem（3））; 
    _collection.Add（new TestItem（1））; 
    
    _view = CollectionViewSource.GetDefaultView（_collection）; 
    _view.SortDescriptions.Add（new SortDescription（Sequence，ListSortDirection.Ascending））; 
   } 
    
    
   } 
    
    private void Button_Click（object sender，RoutedEventArgs e）
    {
    DataContext = new ViewModel ）; 
   } 
   } 
     

程序启动后，datagrid包含（如预期）：

1

2

3

4

5

点击按钮：

5

2

4

3，
1

但是我真的不明白为什么。我做错了，还是这个bug？如果这是一个错误，是否有解决方法？

解决方案

我刚遇到这个bug。 （或至少我认为它是一个错误）。

调试时，可以看到在将ViewModel分配给DataContext之后，SortDescriptions集合被清除。 >

作为一个工作，我从ViewModel的CTOR中删除了SortDescriptions，并将它们放在一个公共方法中，然后在将ViewModel分配给DataContext之后调用它。

  private void Button_Click（object sender，RoutedEventArgs e）
 {
 var model = new ViewModel（）; 
 DataContext = model; // SortDescriptions集合在这里被清除。 
 model.AddSortDescriptions（）; 
 model.View.Refresh（）; 
} 
  

这是远非理想的，但这似乎是唯一的解决方法找到。

maybe someone can help me? I have the following scenario:

1. A simple view:

   <Window x:Class="DataGridSortBug.MainWindow"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         Title="MainWindow" Height="350" Width="525">
       <DockPanel>
           <StackPanel DockPanel.Dock="Top">
               <Button Click="Button_Click">Refresh</Button>
           </StackPanel>
   
           <DataGrid ItemsSource="{Binding View}" />
      </DockPanel>
   </Window>
   

2. The code behind:

   public partial class MainWindow : Window
   {
       public MainWindow()
       {
           InitializeComponent();
   
           DataContext = new ViewModel();
       }
   
       public class TestItem
       {
           private int _sequence;
           public int Sequence
           {
               get { return _sequence; }
           }
   
           public TestItem(int sequence)
           {
               _sequence = sequence;
           }
       }
   
       public class ViewModel
       {
           ObservableCollection<TestItem> _collection;
   
           private ICollectionView _view;
           public ICollectionView View
           {
               get { return _view; }
           }
   
           public ViewModel()
           {
               _collection = new ObservableCollection<TestItem>();
               _collection.Add(new TestItem(5));
               _collection.Add(new TestItem(2));
               _collection.Add(new TestItem(4));
               _collection.Add(new TestItem(3));
               _collection.Add(new TestItem(1));
   
               _view = CollectionViewSource.GetDefaultView(_collection);
               _view.SortDescriptions.Add(new SortDescription("Sequence", ListSortDirection.Ascending));
           }
   
   
       }
   
       private void Button_Click(object sender, RoutedEventArgs e)
       {
           DataContext = new ViewModel();
       }
   }
   

After the program startup the datagrid contains (as expected):

1
2
3
4
5

After click on the button:

5
2
4
3
1

But I really can't understand why. Am I doing something wrong or is this a bug? And if this is a bug is there a workaround?

解决方案

I just ran into this bug. (Or at least I presume it is a bug).

When debugging, you can see that the SortDescriptions collection gets cleared after assigning the ViewModel to the DataContext.

As a work around, I removed the SortDescriptions from the CTOR of the ViewModel and put them within a public method which I then call after assigning the ViewModel to the DataContext.

private void Button_Click(object sender, RoutedEventArgs e)
{
    var model = new ViewModel();
    DataContext = model;  // SortDescriptions collection is cleared here.
    model.AddSortDescriptions();
    model.View.Refresh();
}

It is far from ideal, however this seems to be the only workaround I could find.

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