c# - 将 "MainView"过滤器中的 DataContext 设置为所有 "ChildView' s”

Question

我想知道这是否是 .NET 的标准功能:在 ParentView 中设置 DataContext 时，它会过滤到所有 subview 。

假设您有 ParentView、ChildView1 和 ChildView2:

<UserControl x:Class="DXWPFApplication1.ParentView"
             xmlns:view="clr-namespace:DXWPFApplication1"
             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">
    <Grid>
        <view:ChildView1  x:Name="childView1"/>
    </Grid>
</UserControl>

<UserControl x:Class="DXWPFApplication1.ChildView1"
             xmlns:view="clr-namespace:DXWPFApplication1"
             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">
    <Grid>
        <view:ChildView2  x:Name="childView2"/>
    </Grid>
</UserControl>

ParentView 背后的代码:

public ParentView() 
        {
            InitializeComponent();

            DataContext = "ViewModel"; //BreakPoint here

            //
            //When the first DataContext is set, all the DataContext's below are set as well
            //

            childView1.DataContext = DataContext;
            childView1.childView2.DataContext = DataContext;
        }

注意:先设置DataContext时断点

为什么我只设置了 ParentView 的 DataContext 而设置了所有 DataContext？

我能做些什么来防止这种情况发生？

Answer 1

这是标准行为，通常也是需要的。为防止出现这种情况，请在标记中将 DataContext 设置为 {x:Null}