c# - WPF 向绑定(bind)集合添加额外项

Question

我有一个 ItemsControl，它有绑定(bind)的项目。正如您在屏幕截图中看到的那样，这些项目绑定(bind)到一个属性，我希望出现一个额外的项目，它的行为与其他项目完全不同。我怎样才能做到这一点(最好只使用 xaml)？

Answer 1

看看Composite Collection . WPF 示例 here或 here .

根据评论，这里是第一个例子的示例代码

<ComboBox>
    <ComboBox.ItemsSource>
        <CompositeCollection>
            <ComboBoxItem Content="All" />
            <CollectionContainer Collection="{Binding Source={StaticResource AllBitsSource}}" />
        </CompositeCollection>
    </ComboBox.ItemsSource>
</ComboBox>

编辑 - MVVM

CollectionContainer 的问题在于它无法访问当前的 DataContext。 StaticResource解决了

xaml

<Window x:Class="WpfApplication5.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:my="clr-namespace:WpfApplication5"
        Title="MainWindow" Height="300" Width="525" FontSize="25">

    <StackPanel Name="stk">
        <StackPanel.Resources>
            <CollectionViewSource x:Key="cvsBooks" Source="{Binding Path=Books}" />
        </StackPanel.Resources>

        <ListBox>
            <ListBox.ItemsSource>
                <CompositeCollection>
                    <ListBoxItem>
                        <StackPanel>
                            <TextBlock Margin="5,0">Not tagged</TextBlock>
                        </StackPanel>
                    </ListBoxItem>
                    <CollectionContainer Collection="{Binding Source={StaticResource cvsBooks}}"/>
                </CompositeCollection>
            </ListBox.ItemsSource>
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding Name}"/>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

        <Button Content="Add" Click="Button_Click"/>
    </StackPanel>
</Window>

C#

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        var vm = new ViewModel();
        this.stk.DataContext = vm;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        //should be Command in MVVM, but this is just example to see that ObservableCollection works
        var btn = sender as Button;
        (btn.DataContext as ViewModel).Books.Add(new Book() { Name = "Book" + DateTime.Now.Second });
    }

}

public class ViewModel
{
    public ViewModel()
    {
        this.Books = new ObservableCollection<Book>();
        this.Books.Add(new Book() { Name = "Book 1" });
        this.Books.Add(new Book() { Name = "Book 2" });
        this.Books.Add(new Book() { Name = "Book 3" });
    }

    public ObservableCollection<Book> Books { get; private set; }
}

public class Book
{
    public string Name { get; set; }
}