Question

我有一个UsersControl.xaml

<UserControl x:Name="userControl" x:Class="Lloyd.Shared.Controls.UsersControl"
         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" 
         xmlns:Interactivity="http://schemas.microsoft.com/expression/2010/interactivity"
         xmlns:Behaviors="clr-namespace:Lloyd.Shared.Controls.Behaviors"
         xmlns:local="clr-namespace:Lloyd.Shared.Controls"
         mc:Ignorable="d" DataContext="{Binding Mode=OneWay, RelativeSource={RelativeSource Self}}"
         d:DesignHeight="300" d:DesignWidth="300">

<Interactivity:Interaction.Behaviors>
    <Behaviors:ImportUsersOnLoadedBehavior />
</Interactivity:Interaction.Behaviors>
<DockPanel LastChildFill="True">
    <Label Content="账号" DockPanel.Dock="Top" FontSize="18.667" />

    <StackPanel Orientation="Horizontal" DockPanel.Dock="Bottom" HorizontalAlignment="Right">
        <Button x:Name="AddAccountButton" Height="26" Width="80" Content="添加" Margin="5" Command="{Binding AddUserCommand}" />
        <Button x:Name="ImportAccountsButton" Height="26" Width="80" Content="导入" Margin="5" Command="{Binding ImportUsersCommand}"/>
        <Button x:Name="DeleteAccountButton" Height="26" Width="80" Content="删除" Margin="5" Command="{Binding RemoveUsersCommand}"/>
    </StackPanel>

    <ListView x:Name="accountListbox" Margin="5" BorderThickness="1" BorderBrush="{DynamicResource AccentColorBrush}" ItemsSource="{Binding UsersCollection}"/>
</DockPanel>

背后的代码

public partial class UsersControl : UserControl
{
    public static ObservableCollection<User> GetUsersCollection(DependencyObject obj)
    {
        return (ObservableCollection<User>)obj.GetValue(UsersCollectionProperty);
    }

    public static void SetUsersCollection(DependencyObject obj, ObservableCollection<User> value)
    {
        obj.SetValue(UsersCollectionProperty, value);
    }

    // Using a DependencyProperty as the backing store for UsersCollection.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty UsersCollectionProperty =
        DependencyProperty.RegisterAttached("UsersCollection", typeof(ObservableCollection<User>), typeof(UsersControl), new FrameworkPropertyMetadata(null,FrameworkPropertyMetadataOptions.AffectsRender));


}

我在MainWindow.xaml中使用此UsersControl并将UsersCollection绑定到主窗口的DataContext。

<Controls:MetroWindow x:Class="ZggwwDocuments.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:c="clr-namespace:Lloyd.Shared.Controls;assembly=Lloyd.Shared.Controls"
    xmlns:vm="clr-namespace:ZggwwDocuments.ViewModels"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:ZggwwDocuments"
    mc:Ignorable="d"
    Title="MainWindow" Height="350" Width="697.514">
<Controls:MetroWindow.DataContext>
    <vm:MainWindowViewModel/>
</Controls:MetroWindow.DataContext>
<Grid Margin="5">
    <c:UsersControl UsersCollection="{Binding Users}"  />
</Grid>

我在MainWindow上设置了断点，它的DataContext和Users属性不为空。但MainWindow.DataContext.Users和UsersControl.UsersCollection之间的绑定失败。以下内容来自“输出”窗口

System.Windows.Data错误：40：BindingExpression路径错误：＆＃39;用户＆＃39;在＆＃39; object＆＃39;上找不到的属性＆＃39;＆＃39; UsersControl＆＃39; （名称=＆＃39;用户控件＆＃39;）＆＃39 ;. BindingExpression：路径=用户;的DataItem =＆＃39; UsersControl＆＃39; （名称=＆＃39;用户控件＆＃39）;目标元素是＆＃39; UsersControl＆＃39; （名称=＆＃39;用户控件＆＃39）;目标属性是＆＃39; UsersCollection＆＃39; （键入＆＃39; ObservableCollection`1＆＃39;）

UsersControl.xaml.cs中的

GetUsersCollection（DependencyObject obj）始终返回null

Answer 1

尝试

ItemsSource="{Binding RelativeSource={RelativeSource AncestorType={x:Type c:UsersControl}}, Path=UsersCollection}"

或者，你可以聪明并且拿走;

<DockPanel LastChildFill="True">
    <Label Content="账号" DockPanel.Dock="Top" FontSize="18.667" />

    <StackPanel Orientation="Horizontal" DockPanel.Dock="Bottom" HorizontalAlignment="Right">
        <Button x:Name="AddAccountButton" Height="26" Width="80" Content="添加" Margin="5" Command="{Binding AddUserCommand}" />
        <Button x:Name="ImportAccountsButton" Height="26" Width="80" Content="导入" Margin="5" Command="{Binding ImportUsersCommand}"/>
        <Button x:Name="DeleteAccountButton" Height="26" Width="80" Content="删除" Margin="5" Command="{Binding RemoveUsersCommand}"/>
    </StackPanel>

    <ListView x:Name="accountListbox" Margin="5" BorderThickness="1" BorderBrush="{DynamicResource AccentColorBrush}" ItemsSource="{Binding UsersCollection}"/>
</DockPanel>

......把它推进去;

<UserControl.Template>
   <ControlTemplate TargetType="{x:Type UserControl}">
      (paste it here)
   </ControlTemplate>
</UserControl.Template>

然后将绑定更改为;

{Binding RelativeSource={RelativeSource TemplatedParent}, Path=UsersCollection}

我个人推荐这种方法而不是第一种方法，因为绑定更快，更不容易......'问题'...而且这也意味着你要覆盖用户控件的模板是什么你真的希望它不仅仅是在现有模板中转储一些XAML。

Answer 2

尝试像bellow：

一样打电话给你的附属物

<c:UsersControl UsersControl.UsersCollection="{Binding Users}"  />

附加属性绑定在我的用户控件中失败

2 个答案: