Silverlight DataBinding Error

Question

I\'ve a GridView which has RowDetail. I want to each time user clicks on the rows get some detail from database, I use Telerik GridView

Answer 1

I've even simplified the accepted solution. It uses the trick that from DataTemplates, you can reference static resources. And in static resources, you can use ElementName in binding.

1. Create a new control:

   public class ElementProxy : DependencyObject
   {
       public DependencyObject Element
       {
           get { return (DependencyObject)GetValue(ElementProperty); }
           set { SetValue(ElementProperty, value); }
       }
   
   public static readonly DependencyProperty ElementProperty =
       DependencyProperty.Register("Element", typeof(DependencyObject), typeof(ElementProxy), new PropertyMetadata(null));
   }
   

2. Put it into static resources of the DataGrid or its parent control and reference it through StaticResource:

   <UserControl.Resources>
       <helpers:ElementProxy Element={Binding ElementName=mainPageView} x:Key="Proxy" />
   </UserControl.Resources>
   

(in column template:)

    <DataTemplate>
        <Grid DataContext={Binding Element.DataContext,Source={StaticResource Proxy}} />
    </DataTemplate>

Answer 2

The reason for this is that WPF's and Silverlights DataGrid columns live outside the logical tree and thus make it impossible to use a binding source specified using ElementName which is common when referencing ViewModel properties such as commands from within DataGrid Template Columns. For more information about this problem see: http://blogs.msdn.com/b/jaimer/archive/2008/11/22/forwarding-the-datagrid-s-datacontext-to-its-columns.aspx

The class below act's as glue between the column and the world around it. It was written for Silverlight's built-in DataGrid but should be easy enough to adapt it for the Telerik Grid. It can be used like this:

<DataTemplate x:Key="ContactRowDetailTemplate" >
  <Grid Background="Transparent"
    DataContext="{Binding ParentDataGrid.DataContext.ContactStatModel, 
    ElementName=shim,Mode=OneTime}">
        <Shims:DataGridShim x:Name="shim"/>
    <Grid.RowDefinitions>
      <RowDefinition Height="28" />
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
      <ColumnDefinition Width="Auto" />
      <ColumnDefinition Width="Auto" />
      <ColumnDefinition Width="Auto" />
    </Grid.ColumnDefinitions>
    <TextBlock Text="Sent SMS Count" Grid.Column="0" Grid.Row="0" />
    <TextBlock Text=":" Grid.Column="1" Grid.Row="0" />
    <TextBlock Text="{Binding SMSCount}" Grid.Column="2" Grid.Row="0" />
  </Grid>
</DataTemplate>

public class DataGridShim : FrameworkElement
{
  /// <summary>
  /// Initializes a new instance of the <see cref="DataGridShim"/> class.
  /// prepares the ParentDataGrid property for consumption by sibling elements in the DataTemplate
  /// </summary>
  public DataGridShim()
  {
    Loaded += (s, re) =>
    {
      ParentDataGrid = GetContainingDataGrid(this);
    };
  }

  /// <summary>
  /// Gets or sets the parent data grid.
  /// </summary>
  /// <value>
  /// The parent data grid.
  /// </value>
  public DataGrid ParentDataGrid { get; protected set; }

  /// <summary>
  /// Walks the Visual Tree until the DataGrid parent is found and returns it
  /// </summary>
  /// <param name="value">The value.</param>
  /// <returns>The containing datagrid</returns>
  private static DataGrid GetContainingDataGrid(DependencyObject value)
  {
    if (value != null)
    {
      DependencyObject parent = VisualTreeHelper.GetParent(value);
      if (parent != null)
      {
        var grid = parent as DataGrid;
        if (grid != null)
          return grid;

        return GetContainingDataGrid(parent);
      }

      return null;
    }

    return null;
  }
}