WPF DatagridTextColumn not changing immediately when a DataGridComboBoxColumn’s selection is changed

Hi

I have 2 Tables in a typical Master-Detail relationship :

1) AcctGrps is the Master table. It has 2 columns : AcctGrpCd and AcctGrpName, with AcctGrpCd being the PK.

2) Accts is the Detail table. It has 3 columns : AcctCd, AcctName and AcctGrpCd, with AcctCd being the PK. Thus, each Account has a single AcctGrpCd.

I have a WPF DataGrid in my Window, which displays the Accts data, in the following DataGridColumns :

1) AcctCd  DataGridTextColumn

2) AcctName  DataGridTextColumn

3) AcctGrpCd  DataGridTextColumn

4) AcctGrpName  DataGridComboBoxColumn : This column should be bound such that it displays the AcctGrpName from the AcctGrps table, corresponding to the AcctGrpCd in each Row.

I am retrieving both Tables from the DB, and returning them in DataTable.DefaultView objects, dynamically. (Since the tables are anyway created at runtime, I am not using an ObjectDataProvider.) The DataTable.DefaultView property is of type DataView, which implements the IbindingList interface and therefore provides Change Notifications.

Everything is working perfectly. The only problem is that when I change the selection in the AcctGrpName DataGridComboBoxColumn, the value displayed in the AcctGrpCd DataGridTextColumn changes only when I click on ANOTHER row. I would like the displayed AcctGrpCd to change IMMEDIATELY when the selection is changed in the AcctGrpName DataGridComboBoxColumn. How can I do this ?

The code is shown below :

<Window x:Class="WDataGridAcctsWGrpNames"
   ... ><DockPanel><StackPanel 
           DockPanel.Dock="Top" 
           Orientation="Horizontal"><Button 
                Click="btLoad_Click" 
                Content="Load" Height="23" 
	       Margin="5" 
                Name="btLoad" 
                Width="75" /></StackPanel><DataGrid  
            AutoGenerateColumns="False" 
            DataContext="{Binding}" 
            Height="215" 
            DockPanel.Dock="Top" 
            ItemsSource="{Binding}" 
            Margin="10" 
            Name="dgAccts" 
            Width="407"><DataGrid.Columns><DataGridTextColumn 
                    Header="Acct No" 
                    Binding="{Binding AcctNo}" /><DataGridTextColumn 
                    Header="Acct Name" 
                    Binding="{Binding AcctName}" /><DataGridTextColumn 
                    Header="Acct Grp Cd" 
                    Binding="{Binding AcctGrpCd}" /><DataGridComboBoxColumn 
                    DisplayMemberPath="AcctGrpName" 
                    Header="Acct Group" 
                    ItemsSource="{Binding}" 
                    SelectedValueBinding="{Binding AcctGrpCd}"
                    SelectedValuePath="AcctGrpCd" 
                    x:Name="dgccAcctGrps" /></DataGrid.Columns></DataGrid></DockPanel></Window>
    Private Sub btLoad_Click(
        ByVal sender As System.Object, 
        ByVal e As System.Windows.RoutedEventArgs)
        Try
            ' Disable the Load button.
            btLoad.IsEnabled = False
            ' Display a Wait cursor.
            Me.Cursor = Cursors.Wait
            ' Load Acct Groups data.
            Me.LoadAcctGrps()
            ' Load Accts data.
            Me.LoadAccts()
        Catch ex As Exception
            MessageBox.Show(
              ex.Message,
              ex.GetType.ToString)
        Finally
            ' Enable the Load button.
            btLoad.IsEnabled = True
            ' Display a Default cursor.
            Me.Cursor = Cursors.Arrow
        End Try
    End Sub
    ' Load Acct Groups data.
    Private Sub LoadAcctGrps()…  ' Code to obtain the 
             Acct Groups DataTable …
 
        ' Obtain a reference to the 
          Acct Groups DataTable.
        m_dtAcctGrps = 
              m_dsAcctGrps.Tables(0)
        ' List-Bind the Account Groups 
          DataGridComboBoxColumn to the
	 Account Groups DataTable.
        dgccAcctGrps.ItemsSource = 
               m_dtAcctGrps.DefaultView
    End Sub
    ' Load Accts data.
    Private Sub LoadAccts()
        …  ' Code to obtain the 
             Accts DataTable …
        ' Obtain a reference to the 
          Accts DataTable.
        m_dtAccts = m_dsAccts.Tables(0)
        ' List-bind the Accounts DataGrid to 
          the Accounts DataTable.
        dgAccts.DataContext = 
             m_dtAccts.DefaultView
    End Sub

Please note that DataViews serve as the Binding Source, and they implement the IBindingList interface and therefore already provide Change Notifications.

Perhaps, this problem is being caused because the DataRow’s EndEdit() method is called implicitly, when the user clicks on another Row. I would like to call the EndEdit() method explicitly, but in which event ? The DataGridComboBoxColumn doesn’t provide a SelectionChanged event ! So, in which event can it be called ?

Secondly, does this sort of problem occur if the DataGrid is bound to a List(Of Acct) object and the DataGridComboBoxColumn to a List(Of AcctGrp) object ? I haven’t yet tried this approach and am wondering if this is the standard approach in WPF, rather than binding to a DataView. If so, is it to avoid this kind of a problem ?

Thanks.

Steven