Wpf 带有MVVM指示灯的CommandParameter

我正试图获得一个RelayCommand，它使用一个CommandParameter，使用MVVM Light。该命令在我的viewmodel中定义，我希望将选定的ListBox项作为参数传递。命令已绑定，但参数未绑定。这可能吗

<UserControl x:Class="Nuggets.Metro.Views.EmployeeListView"
         ...
         DataContext="{Binding EmployeeList,Source={StaticResource Locator}}">
   <ListBox x:Name="lstEmployee" ItemsSource="{Binding EmployeeItems}" Style="{StaticResource EmployeeList}" Tag="{Binding EmployeeItems}">
        <ListBox.ContextMenu>
            <ContextMenu DataContext="{Binding Path=PlacementTarget.Tag, RelativeSource={RelativeSource Self}}">
                <MenuItem Header="Edit item" Command="{Binding EditEmployeeCommand}" CommandParameter="{Binding PlacementTarget.SelectedItem,RelativeSource={RelativeSource AncestorType={x:Type ContextMenu}}}"/>
                <MenuItem Header="Delete item" Command="{Binding DeleteEmployeeCommand}" CommandParameter="{Binding PlacementTarget.SelectedItem,RelativeSource={RelativeSource AncestorType={x:Type ContextMenu}}}"/>
            </ContextMenu>
        </ListBox.ContextMenu>

这应该行得通

<ContextMenu DataContext="{Binding Path=PlacementTarget.Tag, RelativeSource={RelativeSource Self}}">
  <MenuItem Header="Edit item" 
            Command="{Binding EditEmployeeCommand}" 
            CommandParameter="{Binding SelectedItem,ElementName=lstEmployee}"/>
  <MenuItem Header="Delete item" 
            Command="{Binding DeleteEmployeeCommand}"
            CommandParameter="{Binding SelectedItem,ElementName=lstEmployee}"/>
 </ContextMenu>

下面的XAML完成了这项工作。使用ContextMenu的PlacementTarget（即列表框）

<ContextMenu DataContext="{Binding Path=PlacementTarget.Tag, RelativeSource={RelativeSource Self}}">
  <MenuItem Header="Edit item" 
            Command="{Binding EditEmployeeCommand}" 
            CommandParameter="{Binding RelativeSource={RelativeSource AncestorType=ContextMenu}, Path=PlacementTarget.SelectedItem}"/>
  <MenuItem Header="Delete item" 
            Command="{Binding DeleteEmployeeCommand}"
            CommandParameter="{Binding RelativeSource={RelativeSource AncestorType=ContextMenu}, Path=PlacementTarget.SelectedItem}"/>
</ContextMenu>

---

这适用于带有MVVM的TreeView或ListView。 ContextMenu中的PlacementTarget（此处）是Listview

<ListView.ContextMenu>
  <ContextMenu>
     <MenuItem x:Name="OpenExplorer"Header="ShowFolder"                  
      Command="{Binding ShowExplorer}"
      CommandParameter ="{Binding Path=PlacementTarget.SelectedItem,
            RelativeSource={RelativeSource AncestorType=ContextMenu}}"/>
   </ContextMenu>
</ListView.ContextMenu>

这似乎合乎逻辑，但：

System.Windows.Data错误：4:找不到引用为“ElementName=lstmemployee”的绑定源。BindingExpression:Path=SelectedItem；DataItem=null；目标元素是“MenuItem”（名称=“”）；目标属性为“CommandParameter”（类型为“Object”）

@Echilon这似乎与您使用的代码相同。对我来说这很有效。也许您的代码中还有另一个问题

<ListView.ContextMenu>
  <ContextMenu>
     <MenuItem x:Name="OpenExplorer"Header="ShowFolder"                  
      Command="{Binding ShowExplorer}"
      CommandParameter ="{Binding Path=PlacementTarget.SelectedItem,
            RelativeSource={RelativeSource AncestorType=ContextMenu}}"/>
   </ContextMenu>
</ListView.ContextMenu>