Setting a listbox selected value when adding a new datagrid row

Hello,

I have a list box and a data grid. When I click on an item in the list box, the datagrid data shows according to the list box selected value.

Here is what I have:

Here is my code:

   public partial class MainWindow : Window
    {
        NorthwindEntities context = new NorthwindEntities();
        public MainWindow()
        {
            InitializeComponent();
        }
        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            CollectionViewSource customerViewSource = ((CollectionViewSource)(this.FindResource("customerViewSource")));
            customerViewSource.Source = DataBase.data.getCustomerList();

            CollectionViewSource orderViewSource = ((CollectionViewSource)(this.FindResource("orderViewSource")));
            orderViewSource.Source = context.Orders.Where(o => o.CustomerID == CustomersListBox.SelectedValue).ToList();
        }

        private void CustomersListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            var orders = context.Orders.Where(o => o.CustomerID == CustomersListBox.SelectedValue).ToList();
            CollectionViewSource orderViewSource = ((CollectionViewSource)(this.FindResource("orderViewSource")));
            orderViewSource.Source = orders;
        }

        private void btnSave_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                context.SaveChanges();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "oh, oh!!!", MessageBoxButton.OK, MessageBoxImage.Error);
            }
        }
    }

Here is my XAML code:

<Window
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:DataBase="clr-namespace:DataBase;assembly=DataBase" mc:Ignorable="d" x:Class="WpfMaserDetailDGToList2.MainWindow"
        Title="MainWindow" Height="485.961" Width="1159.038" Loaded="Window_Loaded"
        xmlns:staticData="clr-namespace:WpfMaserDetailDGToList2"><Window.Resources><CollectionViewSource x:Key="customerViewSource" d:DesignSource="{d:DesignInstance {x:Type DataBase:Customer}, CreateList=True}"/><CollectionViewSource x:Key="orderViewSource" d:DesignSource="{d:DesignInstance {x:Type DataBase:Order}, CreateList=True}"/></Window.Resources><Grid DataContext="{StaticResource customerViewSource}" ><ListBox x:Name="CustomersListBox" HorizontalAlignment="Left" Height="436" Margin="10,10,0,0" VerticalAlignment="Top" Width="147" DisplayMemberPath="CustomerID" ItemsSource="{Binding}" SelectedValuePath="CustomerID" SelectionChanged="CustomersListBox_SelectionChanged" SelectedIndex="0"/><DataGrid x:Name="orderDataGrid" AutoGenerateColumns="False" EnableRowVirtualization="True" ItemsSource="{Binding Source={StaticResource orderViewSource}}" Margin="162,10,177,10" RowDetailsVisibilityMode="VisibleWhenSelected" AlternatingRowBackground="AliceBlue"><DataGrid.Columns><DataGridTextColumn x:Name="customerIDColumn" Binding="{Binding CustomerID}" Header="Customer ID" Width="SizeToHeader" IsReadOnly="True" /><DataGridTextColumn x:Name="employeeIDColumn" Binding="{Binding EmployeeID}" Header="Employee ID" Width="SizeToHeader"/><DataGridTextColumn x:Name="freightColumn" Binding="{Binding Freight}" Header="Freight" Width="SizeToHeader"/><DataGridTemplateColumn x:Name="orderDateColumn" Header="Order Date" Width="120" ><DataGridTemplateColumn.CellTemplate><DataTemplate><DatePicker SelectedDate="{Binding OrderDate, Mode=TwoWay, NotifyOnValidationError=true, ValidatesOnExceptions=true}"/></DataTemplate></DataGridTemplateColumn.CellTemplate></DataGridTemplateColumn><DataGridTextColumn x:Name="orderIDColumn" Binding="{Binding OrderID}" Header="Order ID" Width="SizeToHeader" Visibility="Hidden"/><DataGridTemplateColumn x:Name="requiredDateColumn" Header="Required Date" Width="120"><DataGridTemplateColumn.CellTemplate><DataTemplate><DatePicker SelectedDate="{Binding RequiredDate, Mode=TwoWay, NotifyOnValidationError=true, ValidatesOnExceptions=true}"/></DataTemplate></DataGridTemplateColumn.CellTemplate></DataGridTemplateColumn><DataGridTextColumn x:Name="shipAddressColumn" Binding="{Binding ShipAddress}" Header="Ship Address" Width="SizeToHeader"/><DataGridTextColumn x:Name="shipCityColumn" Binding="{Binding ShipCity}" Header="Ship City" Width="SizeToHeader"/><DataGridTextColumn x:Name="shipCountryColumn" Binding="{Binding ShipCountry}" Header="Ship Country" Width="SizeToHeader"/><DataGridTextColumn x:Name="shipNameColumn" Binding="{Binding ShipName}" Header="Ship Name" Width="SizeToHeader"/><DataGridTemplateColumn x:Name="shippedDateColumn" Header="Shipped Date" Width="120"><DataGridTemplateColumn.CellTemplate><DataTemplate><DatePicker SelectedDate="{Binding ShippedDate, Mode=TwoWay, NotifyOnValidationError=true, ValidatesOnExceptions=true}"/></DataTemplate></DataGridTemplateColumn.CellTemplate></DataGridTemplateColumn><DataGridTextColumn x:Name="shipPostalCodeColumn" Binding="{Binding ShipPostalCode}" Header="Ship Postal Code" Width="SizeToHeader"/><DataGridTextColumn x:Name="shipRegionColumn" Binding="{Binding ShipRegion}" Header="Ship Region" Width="SizeToHeader"/><DataGridTextColumn x:Name="shipViaColumn" Binding="{Binding ShipVia}" Header="Ship Via" Width="SizeToHeader"/></DataGrid.Columns></DataGrid><Button x:Name="btnSave" Content="Save" Height="41" Margin="0,10,10,0" VerticalAlignment="Top" Click="btnSave_Click" HorizontalAlignment="Right" Width="162"/></Grid></Window>

When I click in the datagrid to add a new row, I will like for the customer Id column to automatically take the value of the list so that the customer doesn't have to.

Is there any way to do this?

Guisselle