Binding is not working for property which is of DateTimeOffset? Type

[mageshsankar]

Describe the bug
I am trying to bind value for property of nullable DateTimeOffset type, but binding does not work. But, when I manually set the value for particular property in code behind, it works properly. Please find the Code Snippet for the same below:

Expected behavior
Binding Should work as expected

XAML:

<Page.DataContext>
<local:ViewModel />
</Page.DataContext>

<local:CustomPicker x:Name="customPicker" NullableDateTime="{Binding SelectedDateTime, UpdateSourceTrigger=PropertyChanged}" />

C#:

public class ViewModel : INotifyPropertyChanged
{
private DateTimeOffset dateTime = new DateTimeOffset(new DateTime(2019, 1, 1));

    public DateTimeOffset? SelectedDateTime
    {
        get
        {
            return dateTime;
        }
        set
        {
            dateTime = value.Value;
            this.RaisePropertyChanged(nameof(this.SelectedDateTime));
        }
    }



    /// <summary>
    /// Raised when a property on this object has a new value.
    /// </summary>        
    public event PropertyChangedEventHandler PropertyChanged;




    /// <summary>
    /// Raises this object's PropertyChanged event.
    /// </summary>
    /// <param name="propertyName">The property that has a new value.</param>
    protected virtual void RaisePropertyChanged(string propertyName)
    {
        if (this.PropertyChanged != null)
        {
            this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}



public class CustomPicker : Control
{
    public DateTimeOffset? NullableDateTime
    {
        get { return (DateTimeOffset?)GetValue(NullableDateTimeProperty); }
        set { SetValue(NullableDateTimeProperty, value); }
    }



    // Using a DependencyProperty as the backing store for MyProperty.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty NullableDateTimeProperty =
        DependencyProperty.Register("NullableDateTime", typeof(DateTimeOffset?), typeof(CustomPicker), new PropertyMetadata(null, OnDateTimeChangedAsync));



    /// <summary>
    /// Occurs when the <see cref="NullableDateTime"/> property is changed.
    /// </summary>
    /// <param name="sender">The d<see cref="DependencyObject"/>.</param>
    /// <param name="args">The e<see cref="DependencyPropertyChangedEventArgs"/>.</param>
    private static async void OnDateTimeChangedAsync(DependencyObject sender, DependencyPropertyChangedEventArgs args)
    {
        var dialog = new MessageDialog("Nullable DateTime property value changed");
        _ = await dialog.ShowAsync();
    }
}

Version Info

NuGet package version:

Windows app type:

UWP	Win32
Yes

Windows 10 version	Saw the problem?
Insider Build (xxxxx)
May 2020 Update (19041)	Yes
November 2019 Update (18363)
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Xbox
Surface Hub
IoT

Additional context

[StephenLPeters]

@mageshsankar did you find this issue using Winui3 or system xaml (winui2)?

[mageshsankar]

Hi @StephenLPeters

I have found the issue in WinUi 3

Thanks

[stevenbrix]

@mageshsankar does this work with x:Bind? And do you know if it's just DateTimeOffset or is it any nullable type?

[mageshsankar]

@stevenbrix issue occurs only for nullable type, as you suggested x:Bind is working properly for nullable DateTimeOffset ,

The same scenario(binding) working properly for nullable DateTime type.

Issue only with nullable DateTimeOffset type

[mageshsankar]

Hi Team,

Is there any workaround solution to resolve the binding issue in custom control(CustomPicker) itself instead of using x:bind in application level.

[mageshsankar]

Hi Team,

Any update on this?

[wbokkers]

I can't x:Bind the Date property of CalendarDatePicker to DateTimeOffset (nullable or not), without getting an exception in WinUI 3 Preview 4

[tanothing]

Hi Team,
Any update on this issue? I had same issue with Nullable DateTime too. I cannot bind string to LowerValue on XAML. Please take a look at this issue. Thanks!
[DefaultValue(typeof(DateTime), "")]
public DateTime? LowerValue
{
get => _lowerValue;
set => SetLowerValue(value, false);
}

[sethuramkumar]

Hi Team,
Any updates on the above issue?
Any workaround/fix instead of using x;Bind ?