public partial class Customers : UXPage
{
    public MobilePhones()
    {
        InitializeComponent();
    }

    protected override void OnNavigatedFrom(NavigationEventArgs e)
    {
        base.OnNavigatedFrom(e);
    }        
    
    // Executes when the user navigates to this page.
    protected override void OnNavigatedTo(NavigationEventArgs e)
    {
        LoadData(this.NavigationContext.QueryString);
    }

    // Called when a child navigation has occurred.
    protected override void OnChildNavigation(ChildNavigationEventArgs e)
    {
        LoadData(e.QueryString);
    }
    ...
}