用户控件的DependencyProperty在ListView的结合 [英] UserControl DependencyProperty binding in ListView

问题描述

当我尝试在ListView使用自定义用户控件，它失败，只有空块显示（以下TextBlock的工作虽然）。而在ListView外customControl工作pretty好。有什么问题？

---

MainWindow.xaml

 ＆LT;网格和GT;
    ＆LT;＆StackPanel的GT;
        ＆LT;控制：CustomControl X：NAME =customControlCustomText =测试/＆GT;
        ＆LT; ListView的X：名称=ListView控件＆GT;
            ＆LT; ListView.ItemTemplate＆GT;
                ＆LT;＆DataTemplate的GT;
                    ＆LT;＆StackPanel的GT;
                        ＆LT;控制：CustomControl CustomObject ={结合}/＆GT;
                        ＆LT; TextBlock的文本={结合文字}/＆GT;
                    ＆LT; / StackPanel的＆GT;
                ＆LT; / DataTemplate中＆GT;
            ＆LT; /ListView.ItemTemplate>
        ＆LT; /＆的ListView GT;
    ＆LT; / StackPanel的＆GT;
＆LT; /网格和GT;
 

MainWindow.cs

 公共部分类主窗口：窗口
{
    公共主窗口（）
    {
        的InitializeComponent（）;
        InitializeMyComponent（）;
    }    公共System.Collections.ObjectModel.ObservableCollection＆LT; CustomClass＆GT; CustomCollection的{搞定;组; }    私人无效InitializeMyComponent（）
    {
        this.CustomCollection =新System.Collections.ObjectModel.ObservableCollection＆LT; CustomClass＆GT;（）;
        this.CustomCollection.Add（新CustomClass（）{总数= 1，文本=A}）;
        this.CustomCollection.Add（新CustomClass（）{总数= 2，文本=B}）;
        this.CustomCollection.Add（新CustomClass（）{总数= 3，文本=C}）;
        this.listView.ItemsSource = this.CustomCollection;
        this.customControl.Custom =新CustomClass（）{数= 0，文本=customControl};
    }
}
 

CustomControl.xaml

 ＆LT;网格和GT;
    ＆LT;＆StackPanel的GT;
        ＆LT;＆的TextBlock GT;
            ＆LT;运行X：NAME =numberRun文本={结合CustomObject.Number}/＆GT;
            ＆LT;运行X：NAME =textRun文本={结合CustomObject.Text}/＆GT;
            ＆LT;运行文本={结合CustomText}/＆GT;
        ＆LT; / TextBlock的＆GT;
    ＆LT; / StackPanel的＆GT;
＆LT; /网格和GT;
 

CustomControl.cs

 公共部分类CustomControl：用户控件
{
    公共静态只读的DependencyProperty CustomObjectProperty;
    公共静态只读的DependencyProperty CustomTextProperty;    静态CustomControl（）
    {
        CustomObjectProperty = DependencyProperty.Register（CustomObject的typeof（CustomClass）的typeof（CustomControl），新PropertyMetadata（默认值（CustomClass），OnCustomObjectPropertyChanged））;
        CustomTextProperty = DependencyProperty.Register（CustomText的typeof（串）的typeof（CustomControl），新PropertyMetadata（的String.Empty，OnCustomTextPropertyChanged））;
    }
    公共CustomControl（）
    {
        的InitializeComponent（）;
        this.DataContext =这一点;
    }    公共CustomClass CustomObject
    {
        得到
        {
            回报（CustomClass）（this.GetValue（CustomObjectProperty））;
        }
        组
        {
            this.SetValue（CustomObjectProperty，值）;
        }
    }
    公共字符串CustomText
    {
        得到
        {
            回报（字符串）（this.GetValue（CustomTextProperty））;
        }
        组
        {
            this.SetValue（CustomTextProperty，值）;
        }
    }    私有静态无效OnCustomObjectPropertyChanged（DependencyObject的D，DependencyPropertyChangedEventArgs E）{}
    私有静态无效OnCustomTextPropertyChanged（DependencyObject的D，DependencyPropertyChangedEventArgs E）{}
}
 

CustomClass.cs

 公共类CustomClass：INotifyPropertyChanged的
{
    私人诠释数目;
    私人字符串文本;    公共CustomClass（）
    {
        this.number = INT新（）;
        this.text =的String.Empty;
    }    公众诠释号码
    {
        得到
        {
            返回this.number;
        }
        组
        {
            this.number =价值;
            this.OnPropertyChanged（）;
        }
    }
    公共字符串文本
    {
        得到
        {
            返回this.text;
        }
        组
        {
            this.text =价值;
            this.OnPropertyChanged（）;
        }
    }    公共事件PropertyChangedEventHandler的PropertyChanged;    保护无效OnPropertyChanged（[System.Runtime.CompilerServices.CallerMemberName]字符串名称= NULL）
    {
        PropertyChangedEventHandler处理器= this.PropertyChanged;
        如果（处理！= NULL）
        {
            处理器（这一点，新PropertyChangedEventArgs（名））;
        }
    }
}
 

解决方案

设置用户控件的的DataContext 像

的用户控件实例

  this.DataContext =这一点;
 

有效prevents绑定外部，继承的DataContext，如预期在

 ＆LT;控制：CustomControl CustomObject ={结合}/＆GT;
 

作为一般规则，的从不的设置用户控件的DataContext的明确。在该用户的XAML与的RelativeSource取下用户控件的构造上面一行，并写入绑定：

 ＆LT;运行X：NAME =numberRun文本={结合CustomObject.Number，
    的RelativeSource = {的RelativeSource AncestorType =用户控件}}/＆GT;
 

When I try to use a custom UserControl in a ListView, it fails and only empty blocks are displayed (the following TextBlock works though). While the customControl outside the ListView works pretty well. What's the problem?

---

MainWindow.xaml

<Grid>
    <StackPanel>
        <controls:CustomControl x:Name="customControl" CustomText="Test"/>
        <ListView x:Name="listView">
            <ListView.ItemTemplate>
                <DataTemplate>
                    <StackPanel>
                        <controls:CustomControl CustomObject="{Binding}"/>
                        <TextBlock Text="{Binding Text}"/>
                    </StackPanel>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>
    </StackPanel>
</Grid>

MainWindow.cs

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        InitializeMyComponent();
    }

    public System.Collections.ObjectModel.ObservableCollection<CustomClass> CustomCollection { get; set; }

    private void InitializeMyComponent()
    {
        this.CustomCollection = new System.Collections.ObjectModel.ObservableCollection<CustomClass>();
        this.CustomCollection.Add(new CustomClass() { Number = 1, Text = "a" });
        this.CustomCollection.Add(new CustomClass() { Number = 2, Text = "b" });
        this.CustomCollection.Add(new CustomClass() { Number = 3, Text = "c" });
        this.listView.ItemsSource = this.CustomCollection;
        this.customControl.Custom = new CustomClass() { Number = 0, Text = "customControl" };
    }
}

CustomControl.xaml

<Grid>
    <StackPanel>
        <TextBlock>
            <Run x:Name="numberRun" Text="{Binding CustomObject.Number}"/>
            <Run x:Name="textRun" Text="{Binding CustomObject.Text}"/>
            <Run Text="{Binding CustomText}"/>
        </TextBlock>
    </StackPanel>
</Grid>

CustomControl.cs

public partial class CustomControl : UserControl
{
    public static readonly DependencyProperty CustomObjectProperty;
    public static readonly DependencyProperty CustomTextProperty;

    static CustomControl()
    {
        CustomObjectProperty = DependencyProperty.Register("CustomObject", typeof(CustomClass), typeof(CustomControl), new PropertyMetadata(default(CustomClass), OnCustomObjectPropertyChanged));
        CustomTextProperty = DependencyProperty.Register("CustomText", typeof(string), typeof(CustomControl), new PropertyMetadata(string.Empty, OnCustomTextPropertyChanged));
    }
    public CustomControl()
    {
        InitializeComponent();
        this.DataContext = this;
    }

    public CustomClass CustomObject
    {
        get
        {
            return (CustomClass)(this.GetValue(CustomObjectProperty));
        }
        set
        {
            this.SetValue(CustomObjectProperty, value);
        }
    }
    public string CustomText
    {
        get
        {
            return (string)(this.GetValue(CustomTextProperty));
        }
        set
        {
            this.SetValue(CustomTextProperty, value);
        }
    }

    private static void OnCustomObjectPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { }
    private static void OnCustomTextPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { }
}

CustomClass.cs

public class CustomClass : INotifyPropertyChanged
{
    private int number;
    private string text;

    public CustomClass()
    {
        this.number = new int();
        this.text = string.Empty;
    }

    public int Number
    {
        get
        {
            return this.number;
        }
        set
        {
            this.number = value;
            this.OnPropertyChanged();
        }
    }
    public string Text
    {
        get
        {
            return this.text;
        }
        set
        {
            this.text = value;
            this.OnPropertyChanged();
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    protected void OnPropertyChanged([System.Runtime.CompilerServices.CallerMemberName] string name = null)
    {
        PropertyChangedEventHandler handler = this.PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(name));
        }
    }
}

解决方案

Setting a UserControl's DataContext to the UserControl instance like

this.DataContext = this;

effectively prevents bindings to an "external", inherited DataContext, as expected in

<controls:CustomControl CustomObject="{Binding}"/>

As a general rule, never set a UserControl's DataContext explicitly. Remove the above line from the UserControl's constructor, and write the bindings in the UserControl's XAML with RelativeSource:

<Run x:Name="numberRun" Text="{Binding CustomObject.Number,
    RelativeSource={RelativeSource AncestorType=UserControl}}"/>

这篇关于用户控件的DependencyProperty在ListView的结合的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！