WPF-带有子项的菜单项未触发绑定命令 [英] WPF - MenuItem with children not firing bound command

问题描述

所以我整天都把头靠在墙上.

So I've been butting my head against the wall with this one all day.

在我的WPF应用程序(使用MVVM Light)中，我有一个上下文菜单，该菜单绑定到一组视图模型，并且行为不正确.我可以创建菜单，并且一切与我的MenuItems树状运行，正在执行的命令以及正确的参数一起正常运行.我正在使用它制作一个上下文菜单，允许用户向文件夹添加项目.

In my WPF application (using MVVM Light), I have a context menu which is bound to a collection of viewmodels, and it is not behaving quite correctly. I can create my menu, and everything works perfectly with my tree of MenuItems behaving, commands being executed, and the correct parameter coming through. I'm using this to make a context menu which allows a user to add items to folders.

我遇到的问题是，当上下文菜单项包含子项时，将不再触发该命令.因此，我只能将项目添加到没有子文件夹的文件夹中.

The problem that I've run into is that when a context menu item has children, the command is no longer fired. Thusly, I can only add items to folders which have no child folders.

我已经使用Snoop进行了调查，并且我的DataContext对于MenuItem正确显示，并且命令已正确绑定，并且mousedown事件确实被触发.

I've investigated this using Snoop, and my DataContext is showing up correctly for the MenuItem, and the command is bound correctly, and the mousedown event does get fired.

我遇到的问题是，如果MenuItem有子项，则该命令不会被执行.任何没有子项的项目，其命令都没有问题.

我在这里真的很茫然，关于Stack Overflow或MSDN social的每个类似问题仍然没有答案.

I'm really at a loss here, and every similar question on Stack Overflow or MSDN social remains unanswered.

我已将样式设置为绑定.

I've set up my bindings in a style.

<utility:DataContextSpy x:Key="Spy" />

<!-- Context style (in UserControl.Resources) -->

<Style x:Key="ContextMenuItemStyle" TargetType="{x:Type MenuItem}">
    <Setter Property="Header" Value="{Binding Header}"/>
    <Setter Property="ItemsSource" Value="{Binding Children}"/>
    <Setter Property="Command" Value="{Binding Command}" />
    <Setter Property="CommandParameter" Value="{Binding DataContext, Source={StaticResource Spy}" />
    <Setter Property="CommandTarget" Value="{Binding Path=PlacementTarget, RelativeSource={RelativeSource AncestorType=ContextMenu}}"/>
</Style>

<!-- Later in the control -->
<ContextMenu ItemContainerStyle="{StaticResource ContextMenuItemStyle}" ItemsSource="{Binding MenuItems}" />

请注意，DataSpy来自本文，并且按照描述进行工作，以允许我将我用过的控件的数据上下文用作命令参数

Note that the DataSpy comes from this article, and works as described to allow me to use the datacontext of my usedcontrol as a command parameter

http://www.codeproject.com/Articles/27432/WPF中的Artificial-Inheritance-Contexts-in-WPF

这是上下文菜单中使用的视图模型

Here is the viewmodel used for the context menu

public interface IContextMenuItem
{
    string Header { get; }
    IEnumerable<IContextMenuItem> Children { get; }
    ICommand Command { get; set; }
}

public class BasicContextMenuItem : ViewModelBase, IContextMenuItem
{
    #region Declarations

    private string _header;
    private IEnumerable<IContextMenuItem> _children;

    #endregion

    #region Constructor

    public BasicContextMenuItem(string header)
    {
        Header = header;
        Children = new List<IContextMenuItem>();
    }

    #endregion

    #region Observables

    public string Header
    {
        get { return _header; }
        set
        {
            _header = value;
            RaisePropertyChanged("Header");
        }
    }

    public IEnumerable<IContextMenuItem> Children
    {
        get { return _children; }
        set
        {
            _children = value;
            RaisePropertyChanged("Children");
        }
    }

    public ICommand Command { get; set; }

    #endregion
}

这是上下文项的实际使用方式.

Here's the way a context item is actually used.

MenuItems = new List<IContextMenuItem>
{
    new BasicContextMenuItem("New Folder") { Command = NewFolderCommand} ,
    new BasicContextMenuItem("Delete Folder") { Command = DeleteFolderCommand },
    new BasicContextMenuItem("Rename") { Command = RenameFolderCommand },
};

public ICommand NewFolderCommand
{
    get { return new RelayCommand<FolderViewModel>(NewFolder); }
}

private void NewFolder(FolderViewModel viewModel)
{
    // Do work
}

推荐答案

我看到问题出在XAML绑定上.您需要的是 HierarchicalDataTemplate 绑定.该代码不会为我认为导致问题的孩子绑定该命令.

I see the problem is with XAML binding. What you need is HierarchicalDataTemplate binding. The code doesn't bind the command for the children which I believe is causing the issue.

检查是否有帮助-命令绑定无效在动态MVVM上下文菜单中

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