实现 GroupStyle 时 ListCollectionView.Refresh() 抛出 ArgumentOutOfRange 异常

Question

我有一个ComboBox，其ItemsSource 是一个实现过滤和分组的ListCollectionView。如果我在 xaml 中为 ComboBox 指定 GroupStyle，任何时候我第一次从 ComboBoxItems 列表中选择一个项目都会抛出一个 ArgumentOutOfRange 异常：

"Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index"
at System.ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument argument, ExceptionResource resource)
at System.Collections.Generic.List`1.get_Item(Int32 index)
at MS.Internal.Data.CollectionViewGroupInternal.Clear()
at System.Windows.Data.ListCollectionView.PrepareShaping()
at System.Windows.Data.ListCollectionView.PrepareLocalArray()
at System.Windows.Data.ListCollectionView.RefreshOverride()
at System.Windows.Data.CollectionView.RefreshInternal()
at System.Windows.Data.CollectionView.Refresh()
at kcplane.ViewModel.ShipViewModel.set_ComboSearchText(String value)

但是，选择仍然有效，并且选择的更改被识别（例如，触发对相邻 ComboBox 中的项目重新排序，其值取决于该选择）。

如果我实现的搜索功能用于查找选择，那么没有进一步的问题。

我正在尝试对 ComboBoxItems 进行分组并使用自定义函数对其进行过滤。为了为ListCollectionView 对象提供一些上下文，并使代码更易于理解，ComboBox 公开了一系列舰船，这些舰船按其类型（战舰/驱逐舰等）分组。输入ComboBox 会触发一个搜索功能，该功能会根据船只名称是否包含搜索文本来查找船只。

到目前为止，我发现关于ArgumentOutOfRange/IndexOutOfRange 异常的讨论通常与ICollectionViews 相关，但并非所有都与C# 相关，更不用说wpf。 This post from social.microsoft.com 似乎是最相似的，尽管与排序有关。但它归结为同样的错误（ListCollectionView 尝试PrepareShaping()，但失败了）。在那种情况下，我认为问题在于尝试对来自另一个线程的项目进行排序，同时也更改源集合。我在这里所做的只是应用过滤器并添加组描述，所以我相信当调用Refresh() 来刷新ListCollectionView 时，Windows 应该能够同时处理这两者。

XAML (ShipView.xaml)

<ComboBox Name="ShipCombo" Grid.Row="0" Margin="0,0,0,2"
          VerticalContentAlignment="Center"
          HorizontalContentAlignment="Left"
          ItemsSource="{Binding AvailableShipsCV}"
          IsSynchronizedWithCurrentItem="True"
          IsEditable="True"
          StaysOpenOnEdit="True"
          IsTextSearchEnabled="False" 
          Text="{Binding ComboSearchText, Mode=TwoWay}"
          DisplayMemberPath="Name">
    <ComboBox.ItemContainerStyle>
        <Style TargetType="{x:Type ComboBoxItem}">
            <Setter Property="HorizontalAlignment" Value="Stretch"/>
            <Setter Property="VerticalAlignment" Value="Center"/>
            <Setter Property="HorizontalContentAlignment" Value="Left"/>
            <Setter Property="VerticalContentAlignment" Value="Center"/>
        </Style>
    </ComboBox.ItemContainerStyle>

    <!-- If the section below is taken out, no errors will appear -->
    <ComboBox.GroupStyle>
        <GroupStyle>
            <GroupStyle.HeaderTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding Name}"/>
                </DataTemplate>
            </GroupStyle.HeaderTemplate>
        </GroupStyle>
    </ComboBox.GroupStyle>
</ComboBox>

ViewModel (ShipViewModel.cs)

public class ShipViewModel : INotifyPropertyChanged
{
    #region Fields
    //...

    private string comboSearchText;
    #endregion

    #region Constructors
    public ShipViewModel(List<BaseShip> AvailableShips = null, List<BaseEquipment> AvailableEquipment = null)
    {
        AvailableShipsCV = (ListCollectionView)new CollectionViewSource { Source = AvailableShips }.View;
        AvailableShipsCV.Filter = ShipCollectionViewFilter;
        AvailableShipsCV.GroupDescriptions.Add(new PropertyGroupDescription("Type")); //There is a property called "Type" in the BaseShip object
        AvailableShipsCV.CurrentChanged += AvailableShipsCV_CurrentChanged;
        //...
    }
    #endregion Constructors

    #region Events
    public event PropertyChangedEventHandler PropertyChanged;
    #endregion Events

    #region Properties
    public ListCollectionView AvailableShipsCV { get; private set; }

    //...

    public string ComboSearchText
    {
        get
        {
            return comboSearchText;
        }
        set
        {
            comboSearchText = value;

            /////////////////////////////////////
            // This line triggers the error if //
            // GroupStyle is defined in xaml   //
            /////////////////////////////////////
            AvailableShipsCV.Refresh();

            OnPropertyChanged("ComboSearchText");
        }
    }
    #endregion Properties

    #region Methods
    public void OnPropertyChanged(string PropertyName) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(PropertyName));

    // Delegate for filter
    private bool ShipCollectionViewFilter(object item)
    {
        BaseShip ship = item as BaseShip;
        //If the search string is less than three letters long, or if it is empty, then do not filter
        if (ComboSearchText == null || ComboSearchText?.Length < 3) return true;
        return ship.Name.Contains(ComboSearchText);
    }
    #endregion Methods
}

BaseShip 对象 (KancolleObjects.cs)

public class BaseShip
{
    #region Fields
    //...
    #endregion Fields

    #region Constructors
    public BaseShip()
    {
        //...
    }

    //...

    public BaseShip(string[] entries):this()
    {
        //The name gets stored here, and is never changed
        Name = entries[1];
        //...

        //Same with the type, here.
        ShipType_Short shipType;
        if(!Enum.TryParse(entries[4].Split('/')[1], out ShipType))
        {
            Debug.WriteLine($"Did not manage to get ship type for ship {Name}.");
            //This message was never output, so no problems here (every BaseShip in the ListCollectionView has a valid type).
        }
    }
    #endregion Constructors

    #region Properties
    //...
    public string Name { get; }
    //...
    public ShipType_Short Type { get; }
    #endregion Properties

    #region Methods
    //...

    public override string ToString()
    {
        return Name;
    }
    // Because ItemContainerStyle is set, DisplayMemberPath
    // cannot be set in the xaml. This means we have to rely
    // on the default binding for text, which is ToString()
    #endregion Methods

    #region Constants
    public static BaseShip Empty => new BaseShip();
    #endregion Constants
}

public enum ShipType_Short
{
    //...
}

当我搜索我想要的项目时，我希望过滤后的项目仍然根据类型进行排序，我这样做了，但在给我一个我必须处理的ArgumentOutOfRangeexception 之前不是这样。

Answer 1

this answer 可能会帮助你。基本上你应该使用AvailableShipsCV= CollectionViewSource.GetDefaultView(AvailableShips);

如果使用 CollectionViewSource 的 .View 可能会发生异常，因为对 .View 的引用可能会更改。