使用WPF进行问题数据绑定

Question

一直撞到墙上,发现是时候发一个问题了.我有以下用户控件

XAML

<UserControl x:Class="WorkDayManager3.WPF.UserControls.TimeControl"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         mc:Ignorable="d" 
         d:DesignHeight="46" d:DesignWidth="133" Background="Transparent"
         DataContext="{Binding RelativeSource={RelativeSource self}}">    
<Grid Height="44" Width="132" Background="Transparent">
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="29" />            
    </Grid.ColumnDefinitions>

    <TextBox Name="label" Text="{Binding Text}" Grid.ColumnSpan="5"></TextBox>

</Grid>

C#

public partial class TimeControl : UserControl
{
    public string Text
    {

        get { return (string)GetValue(TextProperty); }

        set { SetValue(TextProperty, value); }

    }

    // Using a DependencyProperty as the backing store for Text. This enables animation, styling, binding, etc...

    public static readonly DependencyProperty TextProperty =

    DependencyProperty.Register("Text", typeof(string), typeof(TimeControl), new UIPropertyMetadata("N/A"));

    public TimeControl()
    {
        InitializeComponent();
    }

在我使用控件的窗口中,它在网格中使用,其datacontext设置为StaticResource

    <Grid Grid.Row="1" HorizontalAlignment="Center" DataContext="{StaticResource shiftViewSource}" Name="grid1" Margin="48,10,38,0">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        <TextBox Grid.Column="0" Grid.Row="1" Height="23" TabIndex="2" HorizontalAlignment="Left" Margin="10,5,0,5" Name="shiftNameTextBox" Text="{Binding Path=ShiftName, Mode=TwoWay, ValidatesOnExceptions=true, NotifyOnValidationError=true}" VerticalAlignment="Center" Width="120" />
        <my2:TimeControl Grid.Column="0" Grid.Row="2" Height="23" TabIndex="2" HorizontalAlignment="Left" Margin="10,5,0,5" Name="shiftNameTextBox" Text="{Binding Path=ShiftName, Mode=TwoWay, ValidatesOnExceptions=true, NotifyOnValidationError=true}" VerticalAlignment="Center" Width="120" />
        <my2:TimeControl Grid.Column="0" Grid.Row="3" Text="THIS WORKS OK"/>            
    </Grid>

现在绑定到Path ShiftName的TextBox工作正常并显示文本.当我使用我的控件时,它不会显示预期的文本.但是在第二个例子中,我只是将Text依赖属性设置为"THIS WORKS OK",文本按预期显示.为什么绑定适用于TextBox但不适用于我的控件.我究竟做错了什么？

Answer 1

你已经把它DataContext放在了UserControl自己身上.因此,你的绑定TimeControl的Text属性试图找到一个叫做财产ShiftName上你的TimeControl,不是你的静态资源.如果查看visual studio的输出窗口,您应该会看到一条错误消息.

这是从来没有设置一个好主意,DataContext就UserControl无论如何,因为任何人都可以将其覆盖.你可以这样做:

<UserControl x:Name="root" ...>
    <Grid DataContext="{Binding ElementName=root}"
        ...