UserControl内部的UserControl没有反映ViewModel中的数据

Question

In MainWindow, I am setting its contant to be a UserControl -

<Grid>
    <local:MainControl></local:MainControl>
</Grid>

In MainControl, I am using other UserControls -

    <Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"></RowDefinition>
        <RowDefinition Height="*"></RowDefinition>
        <RowDefinition Height="Auto"></RowDefinition>
    </Grid.RowDefinitions>
    <Grid.Background>
        <LinearGradientBrush StartPoint="0,0" EndPoint="1,1">
            <GradientStop Color="White" Offset="0"></GradientStop>
            <GradientStop Color="LightBlue" Offset="1"></GradientStop>
        </LinearGradientBrush>
    </Grid.Background>
    <Grid Grid.Row="1">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="300"></ColumnDefinition>
            <ColumnDefinition Width="*"></ColumnDefinition>
        </Grid.ColumnDefinitions>
    </Grid>
    <Grid Grid.Row="0">
        <ui:TestHeader Height="20" Padding="20" Margin="2" Background="Gray"></ui:TestHeader>
    </Grid>
</Grid>

Here TestHeader is a simple UserControl -

<UserControl.DataContext>
    <model:TestViewModel></model:TestViewModel>
</UserControl.DataContext>
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"></RowDefinition>
        <RowDefinition Height="*"></RowDefinition>
    </Grid.RowDefinitions>
    <Label Grid.Row="0" Content="{Binding Path=Test}"/>
</Grid>

Now I am able to see the data comming from ViewModel, when I use TestHeader directly in MainWindow, However when I use the same TestHeader in MainControl, its not getting data from ViewModel. How can I tackle this. I think, I missed something, but don't know what.

Please suggest the solution. Thanks in Advance.

Update

I found this -

<Grid Grid.Row="1">
        <ui:TestHeader Height="20" Padding="20" Margin="2" Background="Gray"></ui:TestHeader>
    </Grid>
    <ui:TestHeader Grid.Row="0" Background="Gray" Height="20"></ui:TestHeader>

here, whole contant is in Grid of MainWindow. The outer TestHeader is populating the data, however, the TestHeader inside the Grid is not.

Update

I got my silliest mistake ever -

See the padding and height, both are 20. There is no space for contant.

Answer 1

您需要在父用户控件上设置DataContext （设置为ViewModel），然后使用ViewModel的Properties将其绑定到控件的属性。