Question

我正在尝试将上下文菜单项绑定到我在ViewModel中定义的命令。上下文菜单位于ListView中，我也绑定到CollectionViewSource，我认为这是问题的原因。

我已经设法将listView集合中的选定项目绑定到我的ViewModel，但是当我尝试使用相同的方式将上下文菜单项命令绑定到我的ViewModel时，它不起作用。我希望任何人都有时间阅读下面的所有代码，并让我对我做错了什么有所了解。

聚苯乙烯。我不得不更改一些名称，以免泄露应用程序的内容。

在我的ViewModel中，我定义了以下内容：

public ObservableCollection<ListItemViewModel> ListViewItemViewModels {get; set;}

public MyListItem SelectedListItemViewModel {get; set;}

private RelayCommand _runCommand;
public ICommand RunCommand {
  get {
     return _runCommand ??
       ( _runCommand = new RelayCommand( param => RunReport(), param => CanRunReport ) );
  }
}

private void RunReport() {
    Logger.Debug("Run report");
}

然后在我的视图中，我按如下方式设置了一个ListView：

<ListView DataContext="{StaticResource ListGroups}"
   ItemsSource="{Binding}" 
   ItemContainerStyle="{StaticResource ListItemStyle}" 
   IsSynchronizedWithCurrentItem="True" 
   SelectedItem="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Grid},AncestorLevel=1 }, Path=DataContext.SelectedListItem, UpdateSourceTrigger=PropertyChanged}" 
   Margin="10,10,0,10">
   <ListView.GroupStyle>
        <StaticResourceExtension ResourceKey="AccountGroupStyle"/>
   </ListView.GroupStyle>
   <ListView.View>
       <GridView>
            <GridViewColumn Header="Title" DisplayMemberBinding="{Binding Path=DisplayTitle}"/>
            <GridViewColumn Header="Date" DisplayMemberBinding="{Binding Path=DateString}"/>
        </GridView>
   </ListView.View>
   <ListView.ContextMenu>
       <ContextMenu Name="ListViewContextMenu">
          <MenuItem Header="Run" Command="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Grid},AncestorLevel=1 }, Path=DataContext.RunCommand}"/>
       </ContextMenu>
   </ListView.ContextMenu>


</ListView>

CollectionViewSource的定义如下：

<DataTemplate x:Key="ListViewListTemplate" DataType="{x:Type ViewModels:ListItemViewModel}">
    <StackPanel Orientation="Vertical">
        <TextBlock Text="{Binding Path=DisplayTitle}" Margin="8,0,0,0"/>
    </StackPanel>
</DataTemplate>

<CollectionViewSource Source="{Binding Path=ListItemViewModels}" x:Key="ListItemGroups">
    <CollectionViewSource.GroupDescriptions>
        <PropertyGroupDescription PropertyName="ListItemGroupName"/>
    </CollectionViewSource.GroupDescriptions>
    <CollectionViewSource.SortDescriptions>
        <ComponentModel:SortDescription PropertyName="Index" Direction="Ascending"/>
        <ComponentModel:SortDescription PropertyName="DisplayTitle" Direction="Ascending"/>
    </CollectionViewSource.SortDescriptions>
</CollectionViewSource>

<GroupStyle x:Key="ListItemGroupStyle">
    <GroupStyle.HeaderTemplate>
        <DataTemplate>
            <!-- The text binding here is refered to the property name set above in the propertyGroupDescrition -->
            <TextBlock x:Name="text" Background="{StaticResource DateGroup_Background}" FontWeight="Bold" Text="{Binding Path=Name}"
                      Foreground="White"
                     Margin="1"
                     Padding="4,2,0,2"/>

        </DataTemplate>
    </GroupStyle.HeaderTemplate>
</GroupStyle>

<Style x:Key="ListItemStyle" TargetType="{x:Type ListViewItem}">

    <Setter Property="HorizontalContentAlignment" Value="Stretch"/>

    <!-- 
  Bind the IsSelected property of a ListViewItem to the 
  IsSelected property of a ReconciliationTaskViewModel object.
  -->
    <Setter Property="IsSelected" Value="{Binding Path=IsSelected, Mode=TwoWay}" />
    <Style.Triggers>
        <MultiTrigger>
            <MultiTrigger.Conditions>
                <Condition Property="ItemsControl.AlternationIndex" Value="1" />
                <Condition Property="IsSelected" Value="False" />
                <Condition Property="IsMouseOver" Value="False" />
            </MultiTrigger.Conditions>
            <Setter Property="Background" Value="#EEEEEEEE" />
        </MultiTrigger>
    </Style.Triggers>
</Style>

Answer 1

问题的原因是ContextMenu不属于ListView的逻辑树或可视树，因此RelativeSource / FindAncestor不会工作，并且DataContext不会被继承。

几个月前我发布了a solution这个问题，您可以按如下方式使用它：

<ListView ...>
    <ListView.Resources>
        <local:BindingProxy x:Key="proxy" Data="{Binding}" />
    </ListView.Resources>

    ...

   <ListView.ContextMenu>
       <ContextMenu Name="ListViewContextMenu">
          <MenuItem Header="Run" Command="{Binding Source={StaticResource proxy}, Path=Data.RunCommand}"/>
       </ContextMenu>
   </ListView.ContextMenu>


    ...

</ListView>

将命令绑定到位于ListView内的Context菜单中的viewModel

1 个答案: