Visibility Binding DataGridTextColumn

Question

I am trying to associate the visibility of a column with another element like this:

<Window x:Class="WpfApplication1.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="350" Width="525"> <Window.Resources> <BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" /> </Window.Resources> <StackPanel> <CheckBox x:Name="chkColumnVisible" Content="Show column" /> <DataGrid x:Name="MyDataGrid" AutoGenerateColumns="False"> <DataGrid.Columns> <DataGridTextColumn Header="Column1" Visibility="{Binding ElementName=chkColumnVisible, Path=IsChecked, Converter={StaticResource BooleanToVisibilityConverter}}"/> </DataGrid.Columns> </DataGrid> </StackPanel> 

but I get this error in VS output:

 System.Windows.Data Error: 2 : Cannot find governing FrameworkElement or FrameworkContentElement for target element. BindingExpression:Path=IsChecked; DataItem=null; target element is 'DataGridTextColumn' (HashCode=48860040); target property is 'Visibility' (type 'Visibility') 

Is there a clean XAML way to do this?

Answer 1

DataGrid columns are abstract objects that are not displayed in a visual or logical tree. You cannot use ElementName and RelativeSource . Source combined with x:Reference should work, though:

 Visibility="{Binding Source={x:Reference chkColumnVisible}, Path=IsChecked, Converter={StaticResource BooleanToVisibilityConverter}}" 

Answer 2

I wrote a markup for it:

 using System; using System.ComponentModel; using System.Linq; using System.Reflection; using System.Windows; using System.Windows.Data; using System.Windows.Markup; using System.Xaml; /// <summary> /// Binds to the datacontext of the current root object or ElementName /// </summary> [MarkupExtensionReturnType(typeof(object))] public class NinjaBinding : MarkupExtension { private static readonly DependencyObject DependencyObject = new DependencyObject(); private static readonly string[] DoNotCopy = { "Path", "Source", "ElementName", "RelativeSource", "ValidationRules" }; private static readonly PropertyInfo[] CopyProperties = typeof(Binding).GetProperties().Where(x => !DoNotCopy.Contains(x.Name)).ToArray(); public NinjaBinding() { } public NinjaBinding(Binding binding) { Binding = binding; } public Binding Binding { get; set; } private bool IsInDesignMode { get { return DesignerProperties.GetIsInDesignMode(DependencyObject); } } public override object ProvideValue(IServiceProvider serviceProvider) { if (Binding == null) { throw new ArgumentException("Binding == null"); } if (IsInDesignMode) { return DefaultValue(serviceProvider); } Binding binding = null; if (Binding.ElementName != null) { var reference = new Reference(Binding.ElementName); var source = reference.ProvideValue(serviceProvider); if (source == null) { throw new ArgumentException("Could not resolve element"); } binding = CreateElementNameBinding(Binding, source); } else if (Binding.RelativeSource !=null) { throw new ArgumentException("RelativeSource not supported"); } else { var rootObjectProvider = (IRootObjectProvider)serviceProvider.GetService(typeof(IRootObjectProvider)); if (rootObjectProvider == null) { throw new ArgumentException("rootObjectProvider == null"); } binding = CreateDataContextBinding((FrameworkElement) rootObjectProvider.RootObject, Binding); } var provideValue = binding.ProvideValue(serviceProvider); return provideValue; } private static Binding CreateElementNameBinding(Binding original, object source) { var binding = new Binding() { Path = original.Path, Source = source, }; SyncProperties(original, binding); return binding; } private static Binding CreateDataContextBinding(FrameworkElement rootObject, Binding original) { string path = string.Format("{0}.{1}", FrameworkElement.DataContextProperty.Name, original.Path.Path); var binding = new Binding(path) { Source = rootObject, }; SyncProperties(original, binding); return binding; } private static void SyncProperties(Binding source, Binding target) { foreach (var copyProperty in CopyProperties) { var value = copyProperty.GetValue(source); copyProperty.SetValue(target, value); } foreach (var rule in source.ValidationRules) { target.ValidationRules.Add(rule); } } private static object DefaultValue(IServiceProvider serviceProvider) { var provideValueTarget = (IProvideValueTarget)serviceProvider.GetService(typeof(IProvideValueTarget)); if (provideValueTarget == null) { throw new ArgumentException("provideValueTarget == null"); } var dependencyProperty = (DependencyProperty)provideValueTarget.TargetProperty; return dependencyProperty.DefaultMetadata.DefaultValue; } } 

Allows you to bind the current root object {Window, UserControl, ...} to the DataContext

Usage example (Visible & Visibility are ViewModel properties):

 <DataGrid> <DataGrid.Columns> <DataGridTextColumn Header="DataContext" Visibility="{dataGridBox:NinjaBinding Binding={Binding Visibility}}" /> <DataGridTextColumn Header="Converter" Visibility="{dataGridBox:NinjaBinding Binding={Binding Visible, Converter={StaticResource BooleanToVisibilityConverter}}}" /> <DataGridTextColumn Header="ElementName" Visibility="{dataGridBox:NinjaBinding Binding={Binding IsChecked, ElementName=CheckBox, Converter={StaticResource BooleanToVisibilityConverter}}}" /> </DataGrid.Columns> </DataGrid> 

Answer 3

The solution from Johan Larsson works fine, only FallbackValue from Binding is not forwarded, so I changed it like this:

 private object DefaultValue(IServiceProvider serviceProvider) { if (Binding.FallbackValue != null) return Binding.FallbackValue; var provideValueTarget = (IProvideValueTarget)serviceProvider.GetService(typeof(IProvideValueTarget)); if (provideValueTarget == null) { throw new ArgumentException("provideValueTarget == null"); } var dependencyProperty = (DependencyProperty)provideValueTarget.TargetProperty; return dependencyProperty.DefaultMetadata.DefaultValue; } 

Thus, it can be used like this, for example, to bind to the header:

 <DataGridTemplateColumn Header="{dataGridBox:NinjaBinding Binding={Binding MyHeaderName1, FallbackValue=HeadingNr1}}" />