Can't get my selection in WPF DataGridComboBoxColumn validated

Question

I have a WPF DataGrid where a column, actually a DataGridComboBoxColumn, is bound to a List, the binding works just fine. The problem is when I choose an element from the ComboBox's list it fills the field, but it becomes blank once I leave it, here is my code :

XAML :

<DataGrid Name="dgPrdCmd" AutoGenerateColumns="False" CanUserAddRows="True"CanUserDeleteRows="True">
         <DataGrid.ItemsSource>
               <collections:ArrayList>
                     <local:TestData></local:TestData>    
               </collections:ArrayList>                                                        
         </DataGrid.ItemsSource>                                                                     
         <DataGrid.Columns>                                                        
             <DataGridComboBoxColumn Header="Product Name" x:Name="cb_NomPrdCmd" IsReadOnly="False"/>
             <DataGridTextColumn Header="Quantity"/>
             <DataGridTextColumn Header="Unit Price"/>
         </DataGrid.Columns>
</DataGrid>

and here's my C# :

using (_entieties)
{
     IQueryable<string> pName = from Product in _entieties.Products
                                select Product.prdName;
     foreach (var name in pName) 
     {
         prd.Add(id);          //prd is just a list of strings          
     }
}
//here is the most important part
cb_NomPrdCmd.ItemsSource = prd;

thanx in advance

Answer 1

You are not binding the SelectedValue or SelectedItem of the ComboBox to anything, so no item will get selected.

Set either the SelectedItemBinding or SelectedValueBinding on your DataGridComboBoxColumn to maintain the selected item