自定义 CollectionViewGroup 和 ListCollectionView 但是当向列表框添加新项目时，它现在可以工作

Question

我想向CollectionViewGroup添加一个新属性

所以我参考了这篇文章： Custom CollectionViewType does not support multiple selection using shift key

当点击按钮添加新项目时

collection add success(default count=9, add one, total count=10),

但是listbox 没有显示新的项目组。

也许有些东西无法实现。

请帮帮我，或者给我google的关键字。

谢谢。

[Window1.xaml]

<Window.Resources>
    <CollectionViewSource x:Key="EmployeesSource" Source="{Binding Employees}" CollectionViewType="local:EmployeeCollectionView">

        <CollectionViewSource.GroupDescriptions>
            <PropertyGroupDescription PropertyName="HireDate"/>
        </CollectionViewSource.GroupDescriptions>

    </CollectionViewSource>

    <DataTemplate x:Key="EmployeeTemplate">
        <StackPanel Orientation="Horizontal">
            <TextBlock Text="{Binding FirstName}" />
            <TextBlock Text="{Binding LastName}" />
        </StackPanel>
    </DataTemplate>
</Window.Resources>
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="50"/>
        <RowDefinition Height="*"/>

    </Grid.RowDefinitions>

    <StackPanel Grid.Row="0">
        <Button Name="addItem" Width="50" Height="50" Content="AddItem"  HorizontalAlignment="Left" Click="addItem_Click"/>
    </StackPanel>

    <ListBox Grid.Row="1" ItemsSource="{Binding Source={StaticResource EmployeesSource}}"
     ItemTemplate="{StaticResource EmployeeTemplate}"
     SelectionMode="Extended">
        <ListBox.GroupStyle>
            <x:Static Member="GroupStyle.Default"/>
        </ListBox.GroupStyle>
    </ListBox>
</Grid>

[Window1.xaml.cs]

public partial class Window1 : Window
{


    public ObservableCollection<Employee> Employees { get; set; }

    public Window1()
    {
        InitializeComponent();


        Employees = new ObservableCollection<Employee>
        {
            new Employee { FirstName = "FirstName1", LastName = "LastName1", HireDate = new DateTime(1970, 1, 1) },
            new Employee { FirstName = "FirstName2", LastName = "LastName2", HireDate = new DateTime(1970, 1, 1) },
            new Employee { FirstName = "FirstName3", LastName = "LastName3", HireDate = new DateTime(1980, 1, 1) },
            new Employee { FirstName = "FirstName4", LastName = "LastName4", HireDate = new DateTime(1980, 1, 1) },
            new Employee { FirstName = "FirstName5", LastName = "LastName5", HireDate = new DateTime(1980, 1, 1) },
            new Employee { FirstName = "FirstName6", LastName = "LastName6", HireDate = new DateTime(1990, 1, 1) },
            new Employee { FirstName = "FirstName7", LastName = "LastName7", HireDate = new DateTime(1990, 1, 1) },
            new Employee { FirstName = "FirstName8", LastName = "LastName8", HireDate = new DateTime(1990, 1, 1) },
            new Employee { FirstName = "FirstName9", LastName = "LastName9", HireDate = new DateTime(1990, 1, 1) },
        };
        DataContext = this;
    }

    private void addItem_Click(object sender, RoutedEventArgs e)
    {
        //Employees add suceess(total count=10), but ui does not add the item(1983,1,1)
        Employees.Add(new Employee {
            FirstName = "FirstName10",
            LastName = "LastName10",
            HireDate = new DateTime(1983, 1, 1)
        });
    }
}

class EmployeeCollectionView : ListCollectionView
{
    private readonly IList<EmployeeCollectionViewGroup> _groups;
    public override ReadOnlyObservableCollection<object> Groups
    {
        get { return new ReadOnlyObservableCollection<object>(new ObservableCollection<object>(_groups)); }
    }


    public EmployeeCollectionView(IList list)
        : base(list)
    {
        _groups = list
             .OfType<Employee>()
            .GroupBy(x => x.HireDate)
            .Select(x => new EmployeeCollectionViewGroup(x.Key, x))
            .ToList();
    }


}


class EmployeeCollectionViewGroup : CollectionViewGroup
{
    public EmployeeCollectionViewGroup(object name, IEnumerable<object> protectedItems)
        : base(name)
    {
        foreach (var protectedItem in protectedItems)
            ProtectedItems.Add(protectedItem);
    }

    public override bool IsBottomLevel
    {
        get { return true; }
    }

    //i want to add a new property
    public bool IsDeleting { get; set; } 
}



public class Employee : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;


    private string m_FirstName;
    public string FirstName
    {
        get { return m_FirstName; }
        set
        {
            m_FirstName = value;
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs("FirstName"));
        }
    }




    private string m_LastName;
    public string LastName
    {
        get { return m_LastName; }
        set
        {
            m_LastName = value;
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs("LastName"));
        }
    }



    private DateTime m_HireDate;
    public DateTime HireDate
    {
        get { return m_HireDate; }
        set
        {
            m_HireDate = value;
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs("HireDate"));
        }
    }

}

Answer 1

您的代码已将 ListBox ItemSource 绑定到类 EmployeeCollectionView 的属性 Groups，其类型为 ReadOnlyObservableCollection<object>，它是只读属性。添加新员工时，它无法通知 UI 更新。 您可以尝试将您的 ListBox 标记更改为：

    <ListBox Grid.Row="1" ItemsSource="{Binding Employees}"
             ItemTemplate="{StaticResource EmployeeTemplate}"
             SelectionMode="Extended">
        <ListBox.GroupStyle>
            <x:Static Member="GroupStyle.Default"/>
        </ListBox.GroupStyle>
    </ListBox>

更改 ItemSource 直接绑定到员工。 希望对你有帮助:)