x:Reference can not be resolved after I re-arrange elements in XAML.
Here I present a working code. Just move the DataGrid element so it comes after the button element and the bindings for the MenuItem in ContextMenu and MultiBinding in Button.IsEnabled become broken. In Button.IsEnabled only MultiBinding is broken. It can be replaced with commented block and x:Reference works in that single binding.
Both throw XamlParseException.
So when is that x:Reference actually resolved and why does only some bindings break when referenced element comes after the element that references it?
Here is my XAML:
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:xxx="clr-namespace:WpfApplication1"
Title="MainWindow" SizeToContent="WidthAndHeight">
<Window.Resources>
<xxx:BoolToVisibleConverter x:Key="boolToVisibleConv"></xxx:BoolToVisibleConverter>
<xxx:NullToFalseConverter x:Key="nullToFalseConv"></xxx:NullToFalseConverter>
<xxx:NullsOrToFalseConverter x:Key="nullsOrToFalseConv"></xxx:NullsOrToFalseConverter>
<ContextMenu x:Key="MyMenu">
<MenuItem
Header="Menuitem enabled when row selected"
IsEnabled="{Binding
Path=SelectedItem,
Source={x:Reference dataGridElement},
Converter={StaticResource nullToFalseConv}}" />
</ContextMenu>
</Window.Resources>
<StackPanel>
<DataGrid
Name="dataGridElement"
IsReadOnly="True" />
<Button
Content="Button"
ContextMenu="{StaticResource MyMenu}"
Visibility="{Binding
Path=IsReadOnly,
Source={x:Reference dataGridElement},
Converter={StaticResource boolToVisibleConv}}">
<Button.IsEnabled>
<!--<Binding
Path="SelectedItem"
Source="{x:Reference dataGridElement}"
Converter="{StaticResource nullToFalseConv}"/>-->
<MultiBinding
Converter="{StaticResource nullsOrToFalseConv}">
<Binding
Path="SelectedItem"
Source="{x:Reference dataGridElement}"/>
<Binding
Path="SelectedItem"
Source="{x:Reference dataGridElement}"/>
</MultiBinding>
</Button.IsEnabled>
</Button>
</StackPanel>
</Window>
Here is my Code behind (without usings):
namespace WpfApplication1
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
}
public class BoolToVisibleConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (value == null || (bool)value == false)
return System.Windows.Visibility.Hidden;
else
return System.Windows.Visibility.Visible;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
public class NullsOrToFalseConverter : IMultiValueConverter
{
public object Convert(object[] value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
foreach (object val in value)
{
if (val == null)
return false;
}
return true;
}
public object[] ConvertBack(object value, Type[] targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
public class NullToFalseConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return (value != null);
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
}
I suppose it is because your resources(Window.Resources) will be created first, before referenced instance exists. I would try to solve this through DataContext (ViewModel).
<Window.DataContext>
<yourNameSpace:YourViewModel x:Name="VieModName" />
</Window.DataContext>
<MenuItem Header="HeadrTxt" Command="{Binding CommandInViewModelCmd}" DataContext="{x:Reference Name=VieModName}" />