WPF附加属性绑定失败：无法在非依赖属性上设置Binding

Let's break down the issue and fix it step by step—this is a common gotcha with attached properties in WPF!

Root Cause #

The main problem is a naming convention mismatch between your registered attached property and its accessor methods. WPF relies strictly on the pattern Get[PropertyName] and Set[PropertyName] to map XAML usage to the underlying dependency property. Your code had mismatched names, which confused the XAML parser.

Corrected Attached Property Code #

Here's the fixed AttachedCommandBehavior class with all issues resolved:

public static class AttachedCommandBehavior
{
    #region PreviewMouseLeftButtonUpCommand
    public static readonly DependencyProperty PreviewMouseLeftButtonUpCommandProperty =
        DependencyProperty.RegisterAttached(
            "PreviewMouseLeftButtonUpCommand",
            typeof(ICommand),
            typeof(AttachedCommandBehavior),
            new FrameworkPropertyMetadata(PreviewMouseLeftButtonUpCommandChanged));

    // Correctly named accessor methods matching the property name
    public static void SetPreviewMouseLeftButtonUpCommand(DependencyObject target, ICommand value)
    {
        target.SetValue(PreviewMouseLeftButtonUpCommandProperty, value);
    }

    public static ICommand GetPreviewMouseLeftButtonUpCommand(DependencyObject target)
    {
        return (ICommand)target.GetValue(PreviewMouseLeftButtonUpCommandProperty);
    }

    // Fixed handler name and logic
    private static void PreviewMouseLeftButtonUpCommandChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if (d is UIElement element)
        {
            if (e.NewValue != null && e.OldValue == null)
            {
                element.PreviewMouseLeftButtonUp += Element_PreviewMouseLeftButtonUp;
            }
            else if (e.NewValue == null && e.OldValue != null)
            {
                element.PreviewMouseLeftButtonUp -= Element_PreviewMouseLeftButtonUp;
            }
        }
    }

    private static void Element_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
    {
        if (sender is UIElement element)
        {
            if (element.GetValue(PreviewMouseLeftButtonUpCommandProperty) is ICommand command)
            {
                // Get the actual parameter value instead of the DependencyProperty object
                var parameter = element.GetValue(CommandParameterProperty);
                command.Execute(parameter);
            }
        }
    }
    #endregion

    #region CommandParameter
    public static readonly DependencyProperty CommandParameterProperty =
        DependencyProperty.RegisterAttached(
            "CommandParameter",
            typeof(object),
            typeof(AttachedCommandBehavior),
            new FrameworkPropertyMetadata(null));

    public static void SetCommandParameter(DependencyObject target, object value)
    {
        target.SetValue(CommandParameterProperty, value);
    }

    public static object GetCommandParameter(DependencyObject target)
    {
        return target.GetValue(CommandParameterProperty);
    }

    // Removed redundant CommandParameterChanged method (the DP system handles value updates automatically)
    #endregion
}

Corrected XAML Usage #

Update your Border to use the correct attached property name (matching the registered property):

<Border 
    Background="{Binding BackgroundColor, Converter={StaticResource ColorNameToBrushConverter}}" 
    Cursor="{x:Static Cursors.Hand}"
    local:AttachedCommandBehavior.PreviewMouseLeftButtonUpCommand="{Binding QueryClickedCommand}"
    <!-- Optional: Add parameter if needed -->
    local:AttachedCommandBehavior.CommandParameter="{Binding YourParameterHere}">
    <Grid>...</Grid>
</Border>

Key Fixes Explained #

1. Accessor Method Naming: Renamed SetPreviewMouseLeftButtonUpChanged to SetPreviewMouseLeftButtonUpCommand to match the registered property name. This is critical—WPF can't find the attached property otherwise.
2. Handler Name Typo: Fixed the duplicate "Preview" in the property changed handler name.
3. Command Parameter Execution: Changed command.Execute(CommandParameterProperty) to pass the actual parameter value from the element, not the DependencyProperty object itself.
4. Redundant Code Removal: Removed the unnecessary CommandParameterChanged method—dependency properties automatically handle value updates, so this was doing nothing useful.

This should resolve both the XAML editor error and the runtime XamlParseException.

内容的提问来源于stack exchange，提问作者jvance