c# - 根据另一个集合设置 ListBox SelectedItems

Question

我有一个ListBox绑定到MyCollection的类型IEnumerable<string>。

 <ListBox x:Name="ListBox" ItemsSource="{Binding MyCollection, Mode=OneWay}" SelectionMode="Multiple"/>

我有另一个List<string> SubCollection包含一个子集MyCollection

每当SubCollection发生变化时，我希望SelectedItems根据SubCollection

是否有任何Binding或Behaviour任何其他方式来实现这一点？

编辑：

假设我ListBox一定要MyCollection { "Orange", "Mango", "Stawberry", "Pineapple" }

假设我按下一个按钮从数据库加载数据，结果是“Orange”、“Mango”，然后放入 to 中SubCollection。ListBox现在应该有 "Orange", "Mango" 作为它的SelectedItems.

score 5 · Accepted Answer

我有一个建议给你。

您可以绑定IsSelected到ListBoxItem.

为此，您必须使用collection of objects（比如说MyListBoxItem）而不是字符串集合。

public class  MyListBoxItem
{
    public string Description { get; set; }
    public bool IsSelected { get; set; }
}

使用这个类的“ ”属性IsSelected来MyListBoxItem绑定.IsSelectedListBoxItem

例如：在您查看模型中，

this.MyCollection = new ObservableCollection<MyListBoxItem>();

MyListBoxItem item1 = new MyListBoxItem()
item1.Description = "Mango";
item1.IsSelected = true;
MyCollection .add(item1);

MyListBoxItem item2 = new MyListBoxItem()
item2 .Description = "Orange";
item2 .IsSelected = false;
MyCollection .add(item2 );

XAML（内部ListBox）

<ListBox.ItemContainerStyle>
    <Style TargetType="{x:Type ListBoxItem}">
        <Setter Property="IsSelected" Value="{Binding Mode=TwoWay, Path=IsSelected}"/>
    </Style>
</ListBox.ItemContainerStyle>

score 4 · Accepted Answer

您可以创建一个List AttachedProperty用于在列表更改时ListBox将项目添加到的。ListBox.SelectedItems

该AttachedProperty解决方案保持WPF清洁和您的MVVM模式，而且它使这个功能在您的所有项目中都可以重用:)

这是一个例子：

附加属性：

public static class ListBoxExtensions
{
    // Using a DependencyProperty as the backing store for SearchValue.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty SelectedItemListProperty =
        DependencyProperty.RegisterAttached("SelectedItemList", typeof(IList), typeof(ListBoxExtensions),
            new FrameworkPropertyMetadata(null, new PropertyChangedCallback(OnSelectedItemListChanged)));

    public static IList GetSelectedItemList(DependencyObject obj)
    {
        return (IList)obj.GetValue(SelectedItemListProperty);
    }

    public static void SetSelectedItemList(DependencyObject obj, IList value)
    {
        obj.SetValue(SelectedItemListProperty, value);
    }

    private static void OnSelectedItemListChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var listbox = d as ListBox;
        if (listbox != null)
        {
            listbox.SelectedItems.Clear();
            var selectedItems = e.NewValue as IList;
            if (selectedItems != null)
            {
                foreach (var item in selectedItems)
                {
                    listbox.SelectedItems.Add(item);
                }
            }
        }
    }
}

Xaml 用法：

<ListBox ItemsSource="{Binding Items}" SelectionMode="Multiple"
         local:ListBoxExtensions.SelectedItemList="{Binding SelectedItems}" />

演示：

如果你想测试的工作示例：

xml:

<Window x:Class="WpfApplication17.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:WpfApplication17"
        Title="MainWindow" Height="227" Width="170" Name="UI">
    <Grid DataContext="{Binding ElementName=UI}">
        <ListBox ItemsSource="{Binding Items}" SelectionMode="Multiple"
                 local:ListBoxExtensions.SelectedItemList="{Binding SelectedItems}"  Margin="0,0,0,37"   >
                 <ListBox.Resources>
                    <SolidColorBrush x:Key="{x:Static SystemColors.ControlBrushKey}" Color="{x:Static SystemColors.HighlightColor}" />
                    <Style TargetType="ListBoxItem">
                       <Style.Triggers>
                          <Trigger Property="IsSelected" Value="True">
                             <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.HighlightTextBrushKey}}"/>
                          </Trigger>
                       </Style.Triggers>
                    </Style>
                 </ListBox.Resources>
        </ListBox>
        <Button Content="Populate SelectedItemList" Click="Button_Click" Height="32" Margin="2,0,1,2" VerticalAlignment="Bottom"/>
    </Grid>
</Window>

代码：

namespace WpfApplication17
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window, INotifyPropertyChanged
    {
        private List<string> _selectedItems = new List<string>();
        private ObservableCollection<string> _items = new ObservableCollection<string> 
        { "Orange", "Mango", "Stawberry", "Pineapple", "Apple", "Grape", "Banana" };

        public MainWindow()
        {
            InitializeComponent();
        }

        public ObservableCollection<string> Items
        {
            get { return _items; }
            set { _items = value; }
        }

        public List<string> SelectedItems
        {
            get { return _selectedItems; }
            set { _selectedItems = value; OnPropertyChanged("SelectedItems"); }
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            SelectedItems = new List<string> { "Orange", "Pineapple", "Apple" };
        }

        public event PropertyChangedEventHandler PropertyChanged;
        public void OnPropertyChanged(string e)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(e));
        }
    }

    public static class ListBoxExtensions
    {
        // Using a DependencyProperty as the backing store for SearchValue.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty SelectedItemListProperty =
            DependencyProperty.RegisterAttached("SelectedItemList", typeof(IList), typeof(ListBoxExtensions),
                new FrameworkPropertyMetadata(null, new PropertyChangedCallback(OnSelectedItemListChanged)));

        public static IList GetSelectedItemList(DependencyObject obj)
        {
            return (IList)obj.GetValue(SelectedItemListProperty);
        }

        public static void SetSelectedItemList(DependencyObject obj, IList value)
        {
            obj.SetValue(SelectedItemListProperty, value);
        }

        private static void OnSelectedItemListChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            var listbox = d as ListBox;
            if (listbox != null)
            {
                listbox.SelectedItems.Clear();
                var selectedItems = e.NewValue as IList;
                if (selectedItems != null)
                {
                    foreach (var item in selectedItems)
                    {
                        listbox.SelectedItems.Add(item);
                    }
                }
            }
        }
    }
}

结果：

在此处输入图像描述

score 2 · Accepted Answer

标准数据绑定不起作用，因为 SelectedItems 属性是只读的。

一种简单的方法是手动迭代 MyCollection 并根据 SubCollection 中的项目设置每个项目的 IsSelected 属性。为此，MyCollection 列表中的项目应包含从 ListBoxItem 继承的对象，这将公开 IsSelected 属性。

这是一个示例 WPF 应用程序来演示它：

单击按钮将根据 SubCollection 列表中的项目更新所选项目。现在我已经硬编码了 SubCollection 列表的值。

根据您的实现，您可以更新您的 SubCollection，并将按钮单击事件中的代码适当地挂钩到任何其他事件。（例如将 SubCollection 列表设置为 ObservableCollection 并挂钩到 ObservableCollection.CollectionChange）

主窗口.xaml

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
        Title="MainWindow" Height="250" Width="255">
    <Grid>
        <StackPanel Orientation="Vertical">
            <ListBox x:Name="ListBox" ItemsSource="{Binding MyCollection}" SelectionMode="Extended" Margin="10,10"/>
            <Button Content="UpdateSelection"  Click="Button_Click" Margin="10,10"/>
        </StackPanel>
    </Grid>
</Window>

主窗口.xaml.cs

namespace WpfApplication1
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            _myCollection = new ObservableCollection<MyListBoxItem>() { new MyListBoxItem("Orange"), new MyListBoxItem("Mango"), new MyListBoxItem("Stawberry"), new MyListBoxItem("Pineapple") };

            //Items to be selected on this.MyCollection ListBox
            this.SubCollection = new List<string>() { "Pineapple", "Mango" };

            this.DataContext = this;
        }

        private ObservableCollection<MyListBoxItem> _myCollection;
        public ObservableCollection<MyListBoxItem> MyCollection
        {
            get { return _myCollection; }
            set
            {
                this._myCollection = value;
            }
        }

        public IList<string> SubCollection { get; set; }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            // Clear all the selected items in the ListBox
            this.MyCollection.ToList().ForEach(item => item.IsSelected = false);

            // SELECT only the items in MySubCollection into this.MyCollection ListBox
            this.MyCollection.Where(item => this.SubCollection.Contains(item.Content.ToString())).ToList().ForEach(item => item.IsSelected= true);
        }
    }

    public class MyListBoxItem : ListBoxItem
    {
        public MyListBoxItem(string displayName)
        {
            this.Content = displayName;
        }
    }
}

score 1 · Accepted Answer

1

查看这篇博文：how-to-databind-to-selecteditems。有一个附有代码的演示项目。

于 2013-03-18T10:05:21.777 回答

score 1 · Accepted Answer

使用SelectedValueListBox 的“”属性。（因为您正在使用字符串集合来绑定列表框。）

在您的视图模型中定义一个字符串类型属性（比如说MySelectedValue）。
然后将其绑定到SelectedValue两个列表框的“”属性。（记得Mode = TwoWay在你的主列表框中设置）
假设当您在子集合列表框中选择一个项目时将执行一个方法。（必须触发SelectionChanged子集合列表框的事件）
就是这样。

所以。你要做的是：

使用相同的属性绑定两个列表框的“SelectedValue”属性。

假设您想将一组对象绑定到列表框。然后使用SelectedItem属性来完成这个任务。

score 0 · Accepted Answer

如果您知道要选择的索引号，可以使用

int[] index = {1, 2, 5};
for( int i in index) 
{    
   listBox.SetSelected( i, true );
}

c# - 根据另一个集合设置 ListBox SelectedItems

6 回答 6

附加属性：

Xaml 用法：

演示：

Related

Reference