WPF ComboBox Mvvm绑定

Question

我试图从列表中获取选定的值到命令中。 有没有简单的方法可以将commandparameter绑定到所选项目？

<ComboBox HorizontalAlignment="Left" Margin="-56,10,0,0" VerticalAlignment="Top" Width="120" SelectedIndex="0" ItemsSource="{Binding Time}">
        <i:Interaction.Triggers>
            <i:EventTrigger EventName="Loaded">
                <i:InvokeCommandAction Command="{Binding TestCommand}" CommandParameter="{Binding }"></i:InvokeCommandAction>
            </i:EventTrigger>
            <i:EventTrigger EventName="SelectionChanged">
                <i:InvokeCommandAction Command="{Binding TestCommand}" CommandParameter="{Binding }"></i:InvokeCommandAction>
            </i:EventTrigger>
        </i:Interaction.Triggers>
    </ComboBox>

当我尝试像

                <i:EventTrigger EventName="SelectionChanged">
                <i:InvokeCommandAction Command="{Binding TestCommand}" CommandParameter="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ComboBox}},Path=SelectionBoxItem}"></i:InvokeCommandAction>
            </i:EventTrigger>

奇怪为什么卡住了？

Answer 1

<ComboBox x:Name="Combo" HorizontalAlignment="Left" Margin="-56,10,0,0" VerticalAlignment="Top" Width="120" SelectedIndex="0" ItemsSource="{Binding Time}">
        <i:Interaction.Triggers>
            <i:EventTrigger EventName="Loaded">
                <i:InvokeCommandAction Command="{Binding TestCommand}" CommandParameter="{Binding ElementName=Combo, Path=SelectedItem}"></i:InvokeCommandAction>
            </i:EventTrigger>
            <i:EventTrigger EventName="SelectionChanged">
                <i:InvokeCommandAction Command="{Binding TestCommand}" CommandParameter="{Binding }"></i:InvokeCommandAction>
            </i:EventTrigger>
        </i:Interaction.Triggers>
    </ComboBox>

如果给组合框命名，则可以使用ElementName绑定并绑定到Path SelectedItem