Windows Phone 7导航传递参数

我有一个如下的列表框。

<ListBox x:Name="CouponListBox" ItemsSource="{Binding Item}" SelectionChanged="CouponListBox_SelectionChanged">
                    <ListBox.ItemTemplate>
                        <DataTemplate>
                            <StackPanel Orientation="Horizontal">
                                <Image Source="{Binding MerchantImage}" Height="73" Width="73" VerticalAlignment="Top" Margin="0,10,8,0"/>
                                <StackPanel Width="130">
                                    <TextBlock Text="{Binding CustomerName}" TextWrapping="Wrap" Style="{StaticResource PhoneTextExtraLargeStyle}"/>
                                    <TextBlock Text="{Binding MerchantName}" TextWrapping="Wrap" FontSize="20" Foreground="#FFC4C4C4" Padding="10" />
                                    <TextBlock Text="{Binding Distance}" TextWrapping="Wrap" FontSize="16" Foreground="#FFC4C4C4" Padding="10" />
                                    <TextBlock Text="{Binding DistanceInMinutes}" TextWrapping="Wrap" FontSize="16" Foreground="#FFC4C4C4" Padding="10" />
                                </StackPanel>
                            </StackPanel>
                        </DataTemplate>
                    </ListBox.ItemTemplate>
                </ListBox>

我在.cs文件中有一个更改事件，它是

private void CouponListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            // If selected index is -1 (no selection) do nothing
            if (CouponListBox.SelectedIndex == -1)
                return;
            // Navigate to the new page
            System.Diagnostics.Debug.WriteLine("this is a test::" + CouponListBox.SelectedItem.ToString());
            NavigationService.Navigate(new Uri("/DetailsPage.xaml?selectedItem=" + CouponListBox.SelectedIndex, UriKind.Relative));
           // Reset selected index to -1 (no selection)
            CouponListBox.SelectedIndex = -1;
        }

在DetailsPage中，我可以打印项目索引。但我想要的是像一样在URL中传递客户ID

"/DetailsPage.xaml?selectedItem=" + CouponListBox.SelectedIndex + "&customerId=" + couponId

有人能告诉我在XAML文件中应该在哪里包含customerId吗？以及我在函数中可以称之为谁。

谢谢，Karthik

if (this.NavigationContext.QueryString.ContainsKey("customerId")) 
{
    string customerId = this.NavigationContext.QueryString["customerId"];
}
if (this.NavigationContext.QueryString.ContainsKey("selectedItem")) 
{
    string selectedItem = this.NavigationContext.QueryString["selectedItem"];
}