Binding Visibility for DataGridColumn in WPF
<Window.Resources>
<ResourceDictionary>
<FrameworkElement x:Key="ProxyElement" DataContext="{Binding}" />
</ResourceDictionary>
</Window.Resources>
<!-- Necessary for binding to resolve: adds reference to ProxyElement to tree.-->
<ContentControl Content="{StaticResource ProxyElement}" Visibility="Collapsed" />
<mch:MCHDataGrid Height="350"
AutoGenerateColumns="False"
FlowDirection="LeftToRight"
ItemsSource="{Binding PayStructures}"
SelectedItem="{Binding SelectedItem}">
<DataGrid.Columns>
<DataGridTemplateColumn Width="70"
Header="name"
IsReadOnly="True"
Visibility="{Binding DataContext.IsShowName,
Source={StaticResource ProxyElement}}">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding FieldName}" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</mch:MCHDataGrid>
Sample of bound property in view model:
private Visibility _isShowName;
public Visibility IsShowName
{
get { return _isShowName; }
set
{
_isShowName = value;
OnPropertyChanged();
}
}
First of all, DataGridTextColumn
(or any other supported dataGrid column) does not lie in the Visual tree of the DataGrid
. Hence, by default it doesn't inherit the DataContext
of the DataGrid
. However, it works for Binding
DP only and for no other DP's on DataGridColumn.
Since they don't lie in the same VisualTree, any attempt to get the DataContext
using RelativeSource
won't work as well because DataGridTextColumn
is unable to traverse up to the DataGrid
.
There are two other ways to achieve this though:
First using a Freezable
class. Freezable
objects can inherit the DataContext even when they’re not in the visual or logical tree –We can take advantage of that.
First, create a class inheriting from Freezable
and Data
DP which we can use to bind in XAML:
public class BindingProxy : Freezable
{
#region Overrides of Freezable
protected override Freezable CreateInstanceCore()
{
return new BindingProxy();
}
#endregion
public object Data
{
get { return (object)GetValue(DataProperty); }
set { SetValue(DataProperty, value); }
}
public static readonly DependencyProperty DataProperty =
DependencyProperty.Register("Data", typeof(object),
typeof(BindingProxy));
}
Now, add an instance of it in DataGrid resources so that it can inherit the DataGrid's DataContext and can bind with its Data DP:
<DataGrid>
<DataGrid.Resources>
<local:BindingProxy x:Key="proxy" Data="{Binding}"/>
</DataGrid.Resources>
<DataGrid.Columns>
<DataGridTextColumn Visibility="{Binding Data.MyColumnVisibility,
Source={StaticResource proxy}}"/>
</DataGrid.Columns>
</DataGrid>
Second, you can refer to any UI element in XAML using ElementName
or x:Reference
. However, ElementName
works only in the same visual tree, whereas x:Reference doesn't have such constraints.
So, we can use that as well to our advantage. Create a dummy FrameworkElement
in XAML with Visibility set to collapsed
. The FrameworkElement will inherit the DataContext from its parent container, which can be a Window or UserControl.
And can use that in DataGrid:
<FrameworkElement x:Name="dummyElement" Visibility="Collapsed"/>
<DataGrid>
<DataGrid.Columns>
<DataGridTextColumn Header="Test"
Binding="{Binding Name}"
Visibility="{Binding DataContext.IsEnable,
Source={x:Reference dummyElement}}"/>
</DataGrid.Columns>
</DataGrid>