I have created a combo box with data binding in WPF. I am not sure how to set value to “comboboxselecteditem”

Question

This is my Xaml code

<Grid>
    <ComboBox Name="C1"  ItemsSource="{Binding}" HorizontalAlignment="Left" Margin="126,127,0,0" VerticalAlignment="Top" Width="218" SelectionChanged="C1_SelectionChanged" >

        <ComboBox.ItemTemplate>
            <DataTemplate>
                <TextBlock Margin="2"  Text="{Binding CUS_DESCRIPTION}" />
            </DataTemplate>
        </ComboBox.ItemTemplate>
        <ComboBox.ItemContainerStyle>
            <Style TargetType="{x:Type ComboBoxItem}">
                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate>
                            <Grid x:Name="gd"  TextElement.Foreground="Black">
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition/>
                                    <ColumnDefinition/>
                                    <ColumnDefinition/>
                                </Grid.ColumnDefinitions>
                                <TextBlock Margin="5" Grid.Column="0" Text="{Binding CUSTOMER_NAME}"/>
                                <TextBlock Margin="5" Grid.Column="1" Text="{Binding CUS_DESCRIPTION}"/>
                            </Grid>
                            <ControlTemplate.Triggers>
                                <Trigger Property="ComboBoxItem.IsSelected" Value="True">
                                    <Setter TargetName="gd"  Property="Background" Value="Gray"></Setter>
                                    <Setter TargetName="gd"  Property="TextElement.Foreground" Value="White"></Setter>
                                </Trigger>
                                <Trigger Property="ComboBoxItem.IsMouseOver" Value="True">
                                    <Setter TargetName="gd"  Property="Background" Value="Blue"></Setter>
                                    <Setter TargetName="gd"  Property="TextElement.Foreground" Value="White"></Setter>
                                </Trigger>

                            </ControlTemplate.Triggers>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
            </Style>
        </ComboBox.ItemContainerStyle>
    </ComboBox>
</Grid>

I have created a combo box with data binding in WPF application. Combo box items are add by using Observable Collection object.I am not sure how to set value of "comboboxselecteditem". I am not able to set a value to combo box as a default value.I need like when window opens the combo box "selectedboxitem" should hold the value that I set.The value is already loaded in combo box by using c# code.

c# code:
 public partial class MainWindow : Window
{
   private ObservableCollection<CUSTOMER> CUSTOMERS=new ObservableCollection<CUSTOMER> ();
    public MainWindow()
    {
        InitializeComponent();
        OleDbConnection connect = new OleDbConnection();
        connect.ConnectionString = @"Provider = Microsoft.ACE.OLEDB.12.0; Data Source = C:\Users\mani\Documents\RAVI.mdb";

        try
        {
            OleDbCommand cmd = new OleDbCommand();
            cmd.CommandType = CommandType.Text;
            cmd.CommandText = "Select * from RICE_CUSTOMER";
            cmd.Connection = connect;
            connect.Open();
            cmd.ExecuteNonQuery();
            OleDbDataReader R1 = cmd.ExecuteReader();
            if (R1.HasRows)
            {
                while (R1.Read())
                {
                    CUSTOMERS.Add(new CUSTOMER() { CUSTOMER_NAME = R1[0].ToString(), CUS_DESCRIPTION = R1[3].ToString() });
                }
                DataContext = CUSTOMERS;
            }     
                     connect.Close();
            ///HOW TO SET COMBOBOX TO THIS VALUE. THIS VALUE ALREADY LOADED IN COMBOBOX BY ABOVE METHOD
            string name="DINESH";
            string DESC = "HELLO";
            C1.SelectedItem = C1.Items.OfType<CUSTOMER>().FirstOrDefault(x => x.CUS_DESCRIPTION==DESC && x.CUSTOMER_NAME==name);        
        }

        catch (OleDbException ex)
        {
            MessageBox.Show(ex.ToString());
        }  
    }

    private void Button_Click_1(object sender, RoutedEventArgs e)
    {  
            Window1 W = new Window1();
            W.Show();
            this.Hide();
    }


    class CUSTOMER
    {
        public string CUSTOMER_NAME{get;set;}
        public string CUS_DESCRIPTION{get;set;}
    }



    private void C1_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        var obj = (CUSTOMER)C1.SelectedItem;
        var getvalue = obj.CUSTOMER_NAME;
        MessageBox.Show(getvalue);  
    }

}

}

I tried 
"C1.SelectedItem = C1.Items.OfType<CUSTOMER>().FirstOrDefault(x => x.CUS_DESCRIPTION==DESC && x.CUSTOMER_NAME==name);" 
but no solution.

Answer 1

What about this?

C1.SelectedItem = CUSTOMERS.FirstOrDefault(x => x.CUS_DESCRIPTION == DESC && x.CUSTOMER_NAME == name);

It should work provided that there actually is such an item in the CUSTOMERS collection. Note that "DINESH" is not the same thing as "Dinesh" here as the comparison is case-sensitive.