DataGrid ListCollectionView排序

Question

我有一个视图模型，它公开了一个ListCollectionView和绑定到它的数据网格。由于某些原因，当交换ListCollectionView并从源集合创建新项时，添加到源集合中的新项的排序会丢失。

源集合是一个ObservableCollection。在创建ListCollectionView时，源集合中已存在的项的排序是正确的。我不使用GetDefaultView，而是在需要的时候自己创建ListCollectionView。向源集合添加新项时，不会进行排序，并且项将显示在列表的末尾。在交换ListCollectionView时引发INotifyPropertyChanged。

有人知道我为什么会有这样的行为吗？

Answer 1

问题可能出在你创建列表集合视图的方式上。(您应该发布该代码。)

我把一些实验性的代码放在一起，它的工作与我预期的一样。我只使用了列表框，但这不会有什么不同。

<Window.DataContext>
    <local:MainWindowViewModel/>
</Window.DataContext>
<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*"/>
        <ColumnDefinition Width="100"/>
    </Grid.ColumnDefinitions>
    <Button Command="{Binding AddPersonCommand}" Grid.Column="1"/>
    <ListBox ItemsSource="{Binding People}"
             >
        <ListBox.ItemTemplate>
            <DataTemplate>
                <TextBlock Text="{Binding LastName}"/>
            </DataTemplate>
        </ListBox.ItemTemplate>
    </ListBox>
</Grid>

视图模型

public class MainWindowViewModel : BaseViewModel
{
    private RelayCommand addPersonCommand;
    public RelayCommand AddPersonCommand
    {
        get
        {
            return addPersonCommand
            ?? (addPersonCommand = new RelayCommand(
              () =>
             {
                 People.Add(new Person { FirstName = "Adam", LastName = "Barlow" });
             }
             ));
        }
    }
    private ObservableCollection<Person> people = new ObservableCollection<Person>();

    public ObservableCollection<Person> People
    {
        get { return people; }
        set { people = value; }
    }


    public ListCollectionView LCV { get; set; }
    public MainWindowViewModel()
    {
        LCV = (ListCollectionView)CollectionViewSource.GetDefaultView(People);
        LCV.SortDescriptions.Add(
            new SortDescription("LastName", ListSortDirection.Ascending));
        People.Add(new Person { FirstName = "Chesney", LastName = "Brown" });
        People.Add(new Person { FirstName = "Gary", LastName = "Windass" });
        People.Add(new Person { FirstName = "Liz", LastName = "McDonald" });
        People.Add(new Person { FirstName = "Carla", LastName = "Connor" });
    }
}

当我单击按钮时，它会将Ken Barlow添加到可观察的集合中，并且它会出现在列表框的顶部。

我还尝试了绑定到LCV：

​

并通过ctor实例化传入的人。

public class MainWindowViewModel : BaseViewModel
{
    private RelayCommand addPersonCommand;
    public RelayCommand AddPersonCommand
    {
        get
        {
            return addPersonCommand
            ?? (addPersonCommand = new RelayCommand(
              () =>
              {
                  Person person = new Person { FirstName = "Adam", LastName = "Barlow" };
                  People.Add(person);
              }
             ));
        }
    }

    private ObservableCollection<Person> people = new ObservableCollection<Person>();

    public ObservableCollection<Person> People
    {
        get { return people; }
        set { people = value; }
    }

    public ListCollectionView LCV { get; set; }
    public MainWindowViewModel()
    {
        People.Add(new Person { FirstName = "Chesney", LastName = "Brown" });
        People.Add(new Person { FirstName = "Gary", LastName = "Windass" });
        People.Add(new Person { FirstName = "Liz", LastName = "McDonald" });
        People.Add(new Person { FirstName = "Carla", LastName = "Connor" });
        LCV = new ListCollectionView(People);
        LCV.SortDescriptions.Add(
            new SortDescription("LastName", ListSortDirection.Ascending));
    }
}

这也是可行的。