如何在没有代码隐藏的情况下将选定的 TreeView 项目传递给 RelayCommand

Question

我有一个 TreeView 装满了我的自定义类型 ToolbarTreeItem 的项目。现在当用户点击一个项目时，我想知道在 MainViewModel.

中点击了哪个项目

我想在没有代码隐藏的情况下实现这一点，但有 RelayCommand。

那么如何将所选项目传递给 RelayCommand 而不必使用标准事件，这会导致代码隐藏？

MainViewModel.cs 中的代码片段：

private ToolbarTreeItem _selectedItem;

private RelayCommand<ToolbarTreeItem> _changeSelectedItem;
public RelayCommand<ToolbarTreeItem> ChangeSelectedItem
{
    get
    {
        return _changeSelectedItem ?? (_changeSelectedItem = new RelayCommand<ToolbarTreeItem>(selectedItem =>
       {
           _selectedItem = selectedItem;
       }));
    }
}

Xaml-Toolbar.xaml 中的片段：

<TreeView SelectedItemChanged="???" />

Answer 1

行为：

public class TreeViewSelection : Behavior<TreeView>
{
    public static readonly DependencyProperty CurrentSelectionProperty = DependencyProperty.Register("CurrentSelection", typeof(object), typeof(TreeViewSelection), new PropertyMetadata(default(object)));

    public object CurrentSelection
    {
        get
        {
            return (object)GetValue(CurrentSelectionProperty);
        }
        set
        {
            SetValue(CurrentSelectionProperty, value);
        }
    }

    protected override void OnAttached()
    {
        base.OnAttached();

        AssociatedObject.SelectedItemChanged += TreeView_SelectedItemChanged;
    }

    private void TreeView_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
    {
        CurrentSelection = e.NewValue;
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();
        AssociatedObject.SelectedItemChanged -= TreeView_SelectedItemChanged;
    }
}

XAML:

xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity" xmlns:b="clr-namespace:NameSpaceWhereBahaviorDefined"

<TreeView ...>
    <i:Interaction.Behaviors>
        <b:TreeViewSelection  CurrentSelection = "{Binding VMSelection}" />
    </i:Interaction.Behaviors>
</TreeView>

如何在没有代码隐藏的情况下将选定的 TreeView 项目传递给 RelayCommand

How to pass selected TreeView item to the RelayCommand without code behind

c#

wpf

mvvm

mvvm-light

relaycommand