XAML绑定用户控件TextBlock将不显示绑定数据 [英] XAML Bind a user controls TextBlock will not show binding data

问题描述

我有一个列表视图控件，该控件使用DataTemplate绑定数据。
创建依赖项后，绑定将使用简单的字符串工作，但在绑定class属性时将无法工作。如果我将数据绑定到textBlock，则可以使用，但是如果我将相同内容绑定到我的用户控件，则无法使用。

I have a list view control that uses the DataTemplate to bind the the data. After I created the dependency the binding works with a simple string but will not work when I bind the class property. If I bind the data to a textBlock it works, but if I bind the same thing to my User Control it doesn't work.

这是我的XAML：LISTVIEW

Here is my XAML: LISTVIEW

<ListView x:Name='lbUsers'
                 Height='370'
                 Canvas.Left='264'
                 Canvas.Top='183'
                 Width='1177'
                  Background='{x:Null}'>

            <ListView.ItemTemplate>
                <DataTemplate>
                    <WrapPanel>
                        <Views:UserSelectRibbon NameText ="{Binding Name}" />
                        <Image Width='10' />
                    </WrapPanel>
                </DataTemplate>
            </ListView.ItemTemplate>

            <ListView.ItemsPanel>
                <ItemsPanelTemplate>
                    <WrapPanel Width="{Binding (FrameworkElement.ActualWidth), 
            RelativeSource={RelativeSource AncestorType=ScrollContentPresenter}}"
                               ItemWidth="{Binding (ListView.View).ItemWidth, 
            RelativeSource={RelativeSource AncestorType=ListView}}"
                               MinWidth="{Binding ItemWidth, RelativeSource={RelativeSource Self}}"
                               ItemHeight="{Binding (ListView.View).ItemHeight, 
            RelativeSource={RelativeSource AncestorType=ListView}}" />
                </ItemsPanelTemplate>
            </ListView.ItemsPanel>

        </ListView>

这里是我的用户控件：

  public string NameText
        {
            get { return (string)GetValue(NameTextProperty); }
            set { SetValue(NameTextProperty, value); }
        }

        public static readonly DependencyProperty NameTextProperty =
            DependencyProperty.Register("NameText", typeof(string), typeof(UserSelectRibbon),null);

        public UserSelectRibbon()
        {
            InitializeComponent();
            DataContext = this;
        }

这里是我的简单用户类别：

HERE IS MY SIMPLE USER CLASS :

public class User {
    public string Name { get; set; }
    public int Age { get; set; }
    public int Playlist { get; set; }
}

SO：
在XAML中，如果我这样做：

SO: In the XAML if I do this : WORKS

  <Views:UserSelectRibbon NameText ="Some text here" /> 

这将起作用并将文本添加到用户控件中的TextBlock中

This will work and add the text to the TextBlock in the user control

但是：
在XAML中，如果我这样做：不要工作

BUT: In the XAML if I do this : DOESN'T"T WORK

<Views:UserSelectRibbon NameText ="{Binding Name}" />

知道为什么没有绑定却可以使用

I would like to know why it works without the binding but it doesn't work with the binding

推荐答案

问题出在您的 DataContext ：

public UserSelectRibbon()
{
    InitializeComponent();
    DataContext = this;
}

以下内容：

<Views:UserSelectRibbon NameText ="{Binding Name}" />

在这里， DataContext 已更改为 Views：UserSelectRibbon ，因此您无法再绑定外部 DataContext 的任何内容。

In here, the DataContext is already changed to the Views:UserSelectRibbon, so you can't bind to anything from the outer DataContext anymore.

解决方案：请勿从内部将 UserControl 的 DataContext 设置为自身。 从不！

Solution: do not set the DataContext of a UserControl to itself from the inside. Never!

相反，请将其设置在usercontrols树内的某个元素上，或使用某些 RelativeSource 或 ElementName 绑定。

Instead, set it on an element inside the usercontrols tree or use some RelativeSource or ElementName binding.

内部DataContext解决方案：

Solution with inner DataContext:

<UserControl ...>
    <Grid x:Name="grid1">
        <TextBlock Text="{Binding NameText}"/>
    </Grid>
</UserControl>

和

public UserSelectRibbon()
{
    InitializeComponent();
    grid1.DataContext = this; // set DataContext on inner control instead of the usercontrol itself
}

使用RelativeSource解决方案（您可以使用 UserControl 基本类型或您特定的用户控件内部类型）：

Solution with RelativeSource (you can use UserControl base type or your specific usercontrols inner type):

<TextBlock Text="{Binding NameText,RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}"/>

使用ElementName的解决方案：

Solution with ElementName:

<UserControl ...
             x:Name="myControl">
    <Grid>
        <TextBlock Text="{Binding NameText,ElementName=myControl}"/>
    </Grid>
</UserControl>

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