wpf datagrid mousebinding leftdoubleclick 命令仅在已选择项目时才有效

Question

我有一个 DataGrid 并希望在我的 ViewModel 中定义的命令在我双击一行时执行。这在该行已被选中时有效，但如果我双击当前未选中的行则不起作用，即使我可以看到 DataGrid 的 MouseDoubleClick 事件正在触发并且所需的行已成为 SelectedItem。这是我的 DataGrid 的定义：

<DataGrid Name="ProjectsList" Grid.Row="1" ItemsSource="{Binding FilteredProjects}" VerticalAlignment="Stretch" 
                      HorizontalAlignment="Stretch" AutoGenerateColumns="False" CanUserAddRows="False" CanUserDeleteRows="False"
                      SelectedItem="{Binding SelectedProject}" PreviewMouseDoubleClick="ProjectsList_PreviewMouseDoubleClick" 
                      MouseDoubleClick="ProjectsList_MouseDoubleClick" >
    <interactivity:Interaction.Behaviors>
        <behaviours:DataGridSelectedProjectsBehaviour SelectedProjects="{Binding SelectedProjects}" />
    </interactivity:Interaction.Behaviors>
    <DataGrid.InputBindings>
        <KeyBinding Key="Delete" Command="{Binding DeleteCommand}" />
        <MouseBinding MouseAction="LeftDoubleClick" Command="{Binding OpenCommand}" />
    </DataGrid.InputBindings>
    <DataGrid.Columns>
        <DataGridTemplateColumn Width="*">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <Grid Margin="0,0,8,0">
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="*" />
                            <ColumnDefinition Width="Auto" />
                        </Grid.ColumnDefinitions>
                        <Grid.RowDefinitions>
                            <RowDefinition />
                            <RowDefinition />
                            <RowDefinition />
                            <RowDefinition />
                        </Grid.RowDefinitions>

                        <Rectangle Grid.Column="0" Grid.Row="0" Grid.ColumnSpan="2" Height="2">
                            <Rectangle.Fill>
                                <LinearGradientBrush StartPoint="0,0" EndPoint="1,0">
                                    <GradientStop Color="{StaticResource SpruceGreen}" Offset="0" />
                                    <GradientStop Color="{StaticResource DarkGrey}" Offset="0.5" />
                                    <GradientStop Color="{StaticResource LightGrey}" Offset="1" />
                                </LinearGradientBrush>
                            </Rectangle.Fill>
                        </Rectangle>
                        <TextBlock Grid.Column="0" Grid.Row="1" Text="{Binding Name}" FontWeight="Bold" />
                        <TextBlock Grid.Column="1" Grid.Row="1" Text="{Binding State}" Foreground="Red" HorizontalAlignment="Right" Typography.Capitals="AllSmallCaps" />
                        <TextBlock Grid.Column="0" Grid.Row="2" Grid.ColumnSpan="2" Text="{Binding Created, Converter={StaticResource StringFormat}, ConverterParameter='CREATED {0:dd/MM/yyyy HH:mm}'}" Foreground="Gray" FontSize="10" />
                        <TextBlock Grid.Column="0" Grid.Row="3" Grid.ColumnSpan="2" Text="{Binding Description}" TextWrapping="Wrap" Padding="0,0,0,32" />
                    </Grid>
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
    </DataGrid.Columns>
</DataGrid>

以下是一些说明问题的日志条目。请原谅我的调试日志条目速记。以 > 结尾的日志条目仅表明调用了该方法（[] 中的名称）。 当我双击当前未选中的行时会发生这种情况：

2017/07/12 16:35:52 DEBUG (ThreadId:1) [DataGridSelectedProjectsBehaviour.OnDataGridSelectionChanged] - > 
2017/07/12 16:35:52 DEBUG (ThreadId:1) [SelectProjectViewModel.SelectedCollectionChanged] - > 
2017/07/12 16:35:52 DEBUG (ThreadId:1) [SelectProjectViewModel.get_SelectedTotal] - > 
2017/07/12 16:35:52 DEBUG (ThreadId:1) [DataGridSelectedProjectsBehaviour.ProjectsCollectionChanged] - > 
2017/07/12 16:35:52 DEBUG (ThreadId:1) [SelectProjectViewModel.SelectedCollectionChanged] - > 
2017/07/12 16:35:52 DEBUG (ThreadId:1) [SelectProjectViewModel.get_SelectedTotal] - > 
2017/07/12 16:35:52 DEBUG (ThreadId:1) [DataGridSelectedProjectsBehaviour.ProjectsCollectionChanged] - > 
2017/07/12 16:35:52 DEBUG (ThreadId:1) [SelectProjectPage.ProjectsList_PreviewMouseDoubleClick] - > 
2017/07/12 16:35:52 DEBUG (ThreadId:1) [SelectProjectPage.ProjectsList_PreviewMouseDoubleClick] - SelectedItem is project [Project2] 
2017/07/12 16:35:52 DEBUG (ThreadId:1) [SelectProjectPage.ProjectsList_MouseDoubleClick] - > 
2017/07/12 16:35:52 DEBUG (ThreadId:1) [SelectProjectPage.ProjectsList_MouseDoubleClick] - SelectedItem is project [Project2] 

当我双击当前选中的一行时会发生这种情况：

2017/07/12 16:35:54 DEBUG (ThreadId:1) [SelectProjectPage.ProjectsList_PreviewMouseDoubleClick] - > 
2017/07/12 16:35:54 DEBUG (ThreadId:1) [SelectProjectPage.ProjectsList_PreviewMouseDoubleClick] - SelectedItem is project [Project2] 
2017/07/12 16:35:54 DEBUG (ThreadId:1) [<Open>d__35.MoveNext] - command was invoked. 
2017/07/12 16:35:54  INFO (ThreadId:1) [BaseViewModel.CheckForUnsavedChanges] - There are no unsaved changes. 
2017/07/12 16:35:54 DEBUG (ThreadId:1) [ProjectSummaryViewModel..ctor] - ViewModel was created. 
2017/07/12 16:35:54 DEBUG (ThreadId:1) [NavigationServiceEx.InternalNavigateTo] - SetParameter finished 
2017/07/12 16:35:54 DEBUG (ThreadId:1) [BaseViewModel.NavigatedFrom] - > 
2017/07/12 16:35:54 DEBUG (ThreadId:1) [SelectProjectPage.ProjectsList_MouseDoubleClick] - > 
2017/07/12 16:35:54 DEBUG (ThreadId:1) [SelectProjectPage.ProjectsList_MouseDoubleClick] - SelectedItem is project [Project2] 

如您所见，如果该行已被选中，则会执行 Open 命令。

我曾认为可能是 DataGridSelectedProjectsBehaviour 干扰了 MouseBinding，但是当我删除它时，双击命令永远不会起作用。我真的不需要它并想删除它。它是在预计需要多行选择时添加的。

任何建议将不胜感激。谢谢

Answer 1

您可以尝试处理 DataGridRow 容器的 MouseDoubleClick 事件，方法是从视图的代码隐藏中调用命令：

<DataGrid Name="ProjectsList" Grid.Row="1" ItemsSource="{Binding FilteredProjects}" VerticalAlignment="Stretch" 
                      HorizontalAlignment="Stretch" AutoGenerateColumns="False" CanUserAddRows="False" CanUserDeleteRows="False"
                      SelectedItem="{Binding SelectedProject}" PreviewMouseDoubleClick="ProjectsList_PreviewMouseDoubleClick" 
                      MouseDoubleClick="ProjectsList_MouseDoubleClick" >
    <DataGrid.RowStyle>
        <Style TargetType="DataGridRow">
            <EventSetter Event="MouseDoubleClick" Handler="OnItemMouseDoubleClick" />
        </Style>
    </DataGrid.RowStyle>
    ...
</DataGrid>

---

private void OnItemMouseDoubleClick(object sender, ouseButtonEventArgs e)
{
    var vm = this.DataContext as YourViewModel;
    vm.YourCommand.Execute(null);
}

或者通过使用附加行为并基本上做同样的事情：

<Style TargetType="DataGridRow">
    <Setter Property="local:YourType.YourAttachedCommandProperty" Value="{Binding DataContext.YourCommand, RelativeSource={RelativeSource AncestorType=DataGrid}}" />
</Style>