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与itemscontrol的twoway绑定

itemscontrol binding wpf

Andrew · 技术社区 · 16 年前

我正在尝试编写一个具有itemsControl的用户控件,其中itemsTemplate包含一个允许twoway绑定的文本框。但是,我一定是在代码的某个地方犯了一个错误,因为绑定似乎只在模式=单向的情况下工作。这是我项目的一个非常简单的摘录,但它仍然包含问题:

<UserControl x:Class="ItemsControlTest.UserControl1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Height="300" Width="300">
    <Grid>
        <StackPanel>
            <ItemsControl ItemsSource="{Binding Path=.}"
                          x:Name="myItemsControl">
                <ItemsControl.ItemTemplate>
                    <DataTemplate>
                        <TextBox Text="{Binding Mode=TwoWay,
                                                UpdateSourceTrigger=LostFocus,
                                                Path=.}" />
                    </DataTemplate>
                </ItemsControl.ItemTemplate>
            </ItemsControl>
            <Button Click="Button_Click"
                    Content="Click Here To Change Focus From ItemsControl" />
        </StackPanel>
    </Grid>
</UserControl>

下面是上述控件的代码隐藏:

using System;
using System.Windows;
using System.Windows.Controls;
using System.Collections.ObjectModel;

namespace ItemsControlTest
{
    /// <summary>
    /// Interaction logic for UserControl1.xaml
    /// </summary>
    public partial class UserControl1 : UserControl
    {
        public ObservableCollection<string> MyCollection
        {
            get { return (ObservableCollection<string>)GetValue(MyCollectionProperty); }
            set { SetValue(MyCollectionProperty, value); }
        }

        // Using a DependencyProperty as the backing store for MyCollection.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty MyCollectionProperty =
            DependencyProperty.Register("MyCollection",
                                        typeof(ObservableCollection<string>),
                                        typeof(UserControl1),
                                        new UIPropertyMetadata(new ObservableCollection<string>()));

        public UserControl1()
        {
            for (int i = 0; i < 6; i++)
                MyCollection.Add("String " + i.ToString());

            InitializeComponent();

            myItemsControl.DataContext = this.MyCollection;
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            // Insert a string after the third element of MyCollection
            MyCollection.Insert(3, "Inserted Item");

            // Display contents of MyCollection in a MessageBox
            string str = "";
            foreach (string s in MyCollection)
                str += s + Environment.NewLine;
            MessageBox.Show(str);
        }
    }
}

最后,这里是主窗口的XAML:

<Window x:Class="ItemsControlTest.Window1"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:src="clr-namespace:ItemsControlTest"
        Title="Window1" Height="300" Width="300">
    <Grid>
        <src:UserControl1 />
    </Grid>
</Window>

好吧,这就是一切。我不知道为什么编辑文本框。窗口中的文本属性似乎没有更新代码隐藏中绑定的源属性,即myCollection。点击按钮会让我的问题直视我的脸;)请帮助我了解我哪里出错了。

谢谢!

安得烈

1 回复 | 直到 14 年前

Charlie 16 年前

好吧,我相信引起这个问题的原因是你直接与 String . 字符串是 不变的 因此,当您更改文本时,它无法更改 ObservableCollection . 要解决这个问题,您只需创建一个模型类来保存字符串数据,然后绑定 TextBox.Text 到该类内的属性。下面是一个例子:

public partial class BindingToString : Window
{
    public BindingToString()
    {
        MyCollection = new ObservableCollection<TestItem>();

        for (int i = 0; i < 6; i++)
            MyCollection.Add(new TestItem("String " + i.ToString()));

        InitializeComponent();

        myItemsControl.DataContext = this.MyCollection;
    }

    public ObservableCollection<TestItem> MyCollection
    {
        get;
        set;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        // Display contents of MyCollection in a MessageBox
        string str = "";
        foreach (TestItem s in MyCollection)
            str += s.Name + Environment.NewLine;
        MessageBox.Show(str);
    }
}

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

    public TestItem(string name)
    {
        Name = name;
    }
}

请注意,我将您的依赖属性更改为标准属性-没有理由使集合成为依赖属性。除此之外,唯一的区别是包含包装类 TestItem 保存字符串数据。

<Window x:Class="TestWpfApplication.BindingToString"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="BindingToString " Height="300" Width="300">
<Grid>
    <StackPanel>
        <ItemsControl ItemsSource="{Binding}"
                      x:Name="myItemsControl">
            <ItemsControl.ItemTemplate>
                <DataTemplate>
                    <TextBox Text="{Binding Path=Name, Mode=TwoWay, UpdateSourceTrigger=LostFocus}"/>
                </DataTemplate>
            </ItemsControl.ItemTemplate>
        </ItemsControl>
        <Button Click="Button_Click"
                Content="Click Here To Change Focus From ItemsControl" />
    </StackPanel>
</Grid>

现在 TextBox 绑定到 Name 路径上 测试项目 ,并且此绑定按预期工作并修改集合。