Question

I want to enable the user to highlight a row on the WPF DataGrid and press delete key to delete the row.

• the functionality is already built into the UI of the grid, so to the user, the row disappears
• I currently handle this on the SelectionChanged event (code below)
• I loop through all the ‘e.RemovedItems’ and delete them with LINQ

Problem is: even when you simply select a row and move off of it, selection change is fired and that row is in e.RemovedItems (which is odd, why would simply selecting something put it in a RemovedItems container?).

So I am looking for a DeleteKeyPressed event so I can simply handle it. What is that event called?

I am using the March 2009 toolkit.

XAML:

<Grid DockPanel.Dock='Bottom'>     <toolkit:DataGrid x:Name='TheDataGrid'                        SelectionChanged='TheDataGrid_SelectionChanged'                       AutoGenerateColumns='True'                       RowEditEnding='TheDataGrid_RowEditEnding'/> 

code-behind:

private void TheDataGrid_SelectionChanged(object sender, System.Windows.Controls.SelectionChangedEventArgs e) {     if (e.RemovedItems.Count > 0)     {         Message.Text = 'The following were removed: ';         foreach (object obj in e.RemovedItems)         {             Customer customer = obj as Customer;             Message.Text += customer.ContactName + ',';             _db.Order_Details.DeleteAllOnSubmit(                 customer.Orders.SelectMany(o => o.Order_Details));             _db.Orders.DeleteAllOnSubmit(customer.Orders);             _db.Customers.DeleteOnSubmit(customer);         }      }      try     {         _db.SubmitChanges();     }     catch (Exception ex)     {         Message.Text = ex.Message;     } } 

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ANSWER:

Thanks lnferis, that was exactly what I was looking for, here is my finished delete handling event for the datagrid, note the KeyDown event doesn’t fire for some reason.

XAML:

<toolkit:DataGrid x:Name='TheDataGrid'                    KeyDown='TheDataGrid_KeyDown'                   PreviewKeyDown='TheDataGrid_PreviewKeyDown'                   AutoGenerateColumns='True'                   RowEditEnding='TheDataGrid_RowEditEnding'/> 

code-behind

private void TheDataGrid_PreviewKeyDown(object sender, KeyEventArgs e) {     if (e.Key == Key.Delete)     {         var grid = (DataGrid)sender;          if (grid.SelectedItems.Count > 0)         {             string checkMessage = 'The following will be removed: ';              foreach (var row in grid.SelectedItems)             {                 Customer customer = row as Customer;                 checkMessage += customer.ContactName + ',';             }             checkMessage = Regex.Replace(checkMessage, ',$', '');              var result = MessageBox.Show(checkMessage, 'Delete', MessageBoxButton.OKCancel);             if (result == MessageBoxResult.OK)             {                 foreach (var row in grid.SelectedItems)                 {                     Customer customer = row as Customer;                     _db.Order_Details.DeleteAllOnSubmit(                         customer.Orders.SelectMany(o => o.Order_Details));                     _db.Orders.DeleteAllOnSubmit(customer.Orders);                     _db.Customers.DeleteOnSubmit(customer);                 }                 _db.SubmitChanges();             }             else             {                 foreach (var row in grid.SelectedItems)                 {                     Customer customer = row as Customer;                     LoadData();                     _db.Refresh(System.Data.Linq.RefreshMode.OverwriteCurrentValues, customer); //TODO: this doesn't refresh the datagrid like the other instance in this code                 }             }         }     } }  private void TheDataGrid_KeyDown(object sender, KeyEventArgs e) {     Console.WriteLine('never gets here for some reason'); } 

Answer 1

The RemovedItems items reflects the items removed from the selection, and not from the grid.

Handle the PreviewKeyDown event, and use the SelectedItems property to delete the selected rows there:

private void PreviewKeyDownHandler(object sender, KeyEventArgs e) {     var grid = (DataGrid)sender;     if ( Key.Delete == e.Key ) {         foreach (var row in grid.SelectedItems) {             ... // perform linq stuff to delete here         }     } }