Xamarin Forms Nullable Property - Object reference not set to an instance of an object

mark Published at Dev

Mark

I'm new to Xamarin Forms and trying to bind a nullable property in XAML :

 public DateTime? LocalExpiryDate  //property on Person class
    {
        get { return GetValue<DateTime>(); }
        set { SetValue(value); }
    }

 <Label Text="{Binding LocalExpiryDate}"/>

And binding in the code behind as:

 InitializeComponent();
 MainStackLayout.BindingContext = member.Person;

Even though the property isn't null when I try and run the app on the Android Emulator I get an error "Exception has been thrown by the target of an invocation", and drilling down into the error I get a message "Object reference not set to an instance of an object"

If I remove the ? to make the property not nullable then the app works fine as long as there is a property

Is it not possible to bind to a nullable property or is there a way around this?

Thanks

Mark

Yehor Hromadskyi

As I understand your issue. I have Page:

public partial class Page1 : ContentPage
{
    private Person _person;
    public Person Person
    {
        get { return _person; }
        set
        {
            _person = value;
            OnPropertyChanged();
        }
    }

    public Page1()
    {
        BindingContext = this;
        InitializeComponent();
    }

    protected override void OnAppearing()
    {
        Person = new Person() { Date = DateTime.Now };

        base.OnAppearing();
    }
}

I have Person:

public class Person : BindableObject
{
    private DateTime? _date;
    public DateTime? Date
    {
        get { return _date; }
        set
        {
            _date = value;
            OnPropertyChanged();
        }
    }
}

And I have XAML:

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
         xmlns:local="clr-namespace:CommonSample;assembly=CommonSample"
         x:Class="CommonSample.Page1">
  <StackLayout>
    <Label Text="{Binding Person.Date}"/>
  </StackLayout>
</ContentPage>

Collected from the Internet

Please contact [email protected] to delete if infringement.