Question

When I use a custome page inheriting from PhoneApplicationPage instead of directly using it, the datepicker throws a null ref exception…

My custom class:

public class CustomPhoneApplicationPage : PhoneApplicationPage
{
  public CustomPhoneApplicationPage()
  {
      Loaded += CustomPhoneApplicationPageLoaded;
      IsAnimFromDisabled = false;
      IsAnimToDisabled = false;
      this.Tap += CustomPhoneApplicationPageTap;
      InitTransition();
  }
  private void InitTransition()
  {
    RenderTransform = new CompositeTransform();
    _comeInStoryboard = Application.Current.Resources["FadeIn"] as Storyboard;
    _comeOutStoryboard = Application.Current.Resources["FadeOut"] as Storyboard;
    Debug.Assert(_comeInStoryboard != null, "_comeInStoryboard != null");
    Debug.Assert(_comeOutStoryboard != null, "_comeOutStoryboard != null");
  }
}

The use of the date picker in the Xaml:

<toolkit:DatePicker x:Name="_dateTimePicker" Value="{Binding SnapshotTime, Mode=TwoWay}" />

The exception is thrown here:

Microsoft.Phone.Controls.Toolkit.dll!Microsoft.Phone.Controls.DataSource.GetPrevious(object relativeTo) + 0x7 bytes

Here is how I use this class as a base for my pages in the app:

public partial class AddOrEditData : CustomPhoneApplicationPage
{


    public AddOrEditData()
    {
        InitializeComponent();
        Loaded += AddOrEditDataLoaded;

    }
...
}

Here is the full stack trace:

Microsoft.Phone.Controls.Toolkit.dll!Microsoft.Phone.Controls.DataSource.GetPrevious(object relativeTo) Line 58 + 0x7 bytes C#
Microsoft.Phone.Controls.Toolkit.dll!Microsoft.Phone.Controls.Primitives.LoopingSelector.Balance() Line 146 + 0xd bytes C#
Microsoft.Phone.Controls.Toolkit.dll!Microsoft.Phone.Controls.Primitives.LoopingSelector.UpdateData() Line 552 + 0xc0 bytes C#
Microsoft.Phone.Controls.Toolkit.dll!Microsoft.Phone.Controls.Primitives.LoopingSelector.LoopingSelector_SizeChanged(object sender, System.Windows.SizeChangedEventArgs e) Line 365 C#
System.Windows.dll!System.Windows.FrameworkElement.OnSizeChanged(object sender, System.Windows.SizeChangedEventArgs e) + 0x15 bytes
System.Windows.dll!MS.Internal.JoltHelper.RaiseEvent(System.IntPtr target, uint eventId, System.IntPtr coreEventArgs, uint eventArgsTypeIndex) + 0xb2 bytes
[Native to Managed Transition]

Answer 1

Ok,

I solved it by adding this line of code to my inheriting page to disable some custom animation when leaving the page:

 protected override void OnNavigatingFrom(System.Windows.Navigation.NavigatingCancelEventArgs e)
    {
        IsAnimFromDisabled = e.Uri.OriginalString == @"/Microsoft.Phone.Controls.Toolkit;component/DateTimePickers/DatePickerPage.xaml";
        base.OnNavigatingFrom(e);
    }

And it works !

Thanks every one !