Question

我想创建一个简化以下代码的自定义控件：

<StackPanel>
    <DockPanel LastChildFill="True">
        <Label>First Name</Label>
        <TextBox Margin="2" Text="{Binding Path=FirstName}"></TextBox>
    </DockPanel>
    <DockPanel LastChildFill="True">
        <Label>Last Name</Label>
        <TextBox Margin="2" Text="{Binding Path=LastName}"></TextBox>
    </DockPanel>
</StackPanel>

我的想法是制作一个UserControl，如下所示，（布局略有不同，但这超出了范围）：

<UserControl x:Class="LabelControl"
             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="300" d:DesignWidth="300">
    <DockPanel LastChildFill="True">
        <Label Content="{Binding Path=Text}" Margin="2" MinWidth="100" HorizontalContentAlignment="Right"></Label>
        <Grid Margin="2">
            <ContentControl Content="{Binding Path=Control}" ></ContentControl>
        </Grid>
    </DockPanel>
</UserControl>

后面的代码公开了2个依赖属性：

文字：标签的内容
控件：由内容托管的控件。该课程使用ContentProperty属性将孩子映射到ContentControl。

因此允许我简化我的StackPanel：

<StackPanel>
    <controls:LabelControl Text="First Name">
        <TextBox Text="{Binding Path=FirstName}"></TextBox>
    </controls:LabelControl>
    <controls:LabelControl Text="Last Name">
        <TextBox Text="{Binding Path=LastName}"></TextBox>
    </controls:LabelControl>
</StackPanel>

我遇到的问题是控件中的绑定没有映射。有没有办法解决？ Label Controls DataContext覆盖父控件上下文。

以下是LabelControl背后的代码：

[ContentProperty("Control")]
public partial class LabelControl : UserControl
{
    public static readonly DependencyProperty TextProperty = DependencyProperty.Register(
        "Text", typeof(string), typeof(LabelControl), new PropertyMetadata(default(string)));

    public string Text
    {
        get { return (string)GetValue(TextProperty); }
        set { SetValue(TextProperty, value); }
    }

    public static readonly DependencyProperty ControlProperty =
        DependencyProperty.Register("Control", typeof(Control), typeof(LabelControl), new PropertyMetadata(default(Control)));

    public Control Control
    {
        get { return (Control)GetValue(ControlProperty); }
        set { SetValue(ControlProperty, value); }
    }

    public LabelControl()
    {
        InitializeComponent();
        this.DataContext = this;
    }
}

编辑：输出确认datacontext重写。

BindingExpression path error: 'FirstName' property not found on 'object' ''LabelControl' (Name='')'. BindingExpression:Path=FirstName; DataItem='LabelControl' (Name=''); target element is 'TextBox' (Name=''); target property is 'Text' (type 'String')

Answer 1

如果LabelControl包含在Window中且DataContext FirstName具有<TextBox Text="{Binding Path=FirstName, RelativeSource={RelativeSource AncestorType=Window}}"> </TextBox>属性，请尝试更改此类绑定。

RelativeSource

如果您不想每次都指定LabelControl，则可以像现在一样使用<StackPanel> <controls:LabelControl Text="First Name"> <TextBox Text="{Binding Path=FirstName}"></TextBox> </controls:LabelControl> <controls:LabelControl Text="Last Name"> <TextBox Text="{Binding Path=LastName}"></TextBox> </controls:LabelControl> </StackPanel> ...

LabelControl

...而是更改DataContext的实施。

首先，从LabelControl的代码隐藏中删除public LabelControl() { InitializeComponent(); //this.DataContext = this; // we don't want this }分配。

<DockPanel LastChildFill="True">
    <Label Content="{Binding Path=Text,
           RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}}" 
           Margin="2" MinWidth="100" HorizontalContentAlignment="Right">
    </Label>
    <Grid Margin="2">
        <ContentControl 
            Content="{Binding Path=Control, 
            RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}}">
        </ContentControl>
    </Grid>
</DockPanel>

然后将XAML模板更改为

DataContext

现在您应该设置{{1}}。

Answer 2

我发现使用UserControl并不是最理想的解决方案。事实证明，模板化控件允许DataBinds在没有任何hackery的情况下通过（RelativeSource）。

[ContentProperty("Control")]
public class LabelControl : Control
{

    public static readonly DependencyProperty TextProperty = DependencyProperty.Register("Text", 
        typeof(string), typeof(LabelControl), new PropertyMetadata(default(string)));

    public string Text
    {
        get { return (string)GetValue(TextProperty); }
        set { SetValue(TextProperty, value); }
    }

    public static readonly DependencyProperty ControlProperty =
        DependencyProperty.Register("Control", typeof(Control), typeof(LabelControl), new PropertyMetadata(default(Control)));

    public Control Control
    {
        get { return (Control)GetValue(ControlProperty); }
        set { SetValue(ControlProperty, value); }
    }
}

在app.xaml：

<Style TargetType="controls:LabelControl">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="controls:LabelControl">
                <DockPanel LastChildFill="True">
                    <Label Content="{TemplateBinding Text}"  MinWidth="100" FontSize="11"></Label>
                    <Grid Margin="2">
                        <ContentControl Content="{TemplateBinding Control}"></ContentControl>
                    </Grid>
                </DockPanel>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

DataContext passthrough与ContentProperty

2 个答案: