I have a Xamarin XAML page with a ListView. The list data source is linked to an observable collection which is populated with realm objects.
When i try to delete an object from the ListView (first from the data source and then from realm) I've got the crash.
The crash occurs later at binding time only on iOS and the inner exception message is:
This object is detached. Was it deleted from the realm?
So, it seems that the object is still accessed from the ListView after deletion.
StackTrace:
at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00050] in /Users/builder/data/lanes/3818/3983064a/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:313
at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) [0x00000] in /Users/builder/data/lanes/3818/3983064a/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/referencesource/mscorlib/system/reflection/methodbase.cs:229
at Xamarin.Forms.BindingExpression+BindingExpressionPart.TryGetValue (System.Object source, System.Object& value) [0x00043] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\BindingExpression.cs:498
at Xamarin.Forms.BindingExpression.Unapply () [0x00030] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\BindingExpression.cs:90
at Xamarin.Forms.Binding.Unapply () [0x0000e] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\Binding.cs:142
at Xamarin.Forms.BindableObject.ApplyBindings (System.Object oldContext, System.Boolean skipBindingContext) [0x0002e] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\BindableObject.cs:407
at Xamarin.Forms.BindableObject.ApplyBindings (System.Object oldContext) [0x00000] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\BindableObject.cs:123
at Xamarin.Forms.BindableObject.SetInheritedBindingContext (Xamarin.Forms.BindableObject bindable, System.Object value) [0x0005a] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\BindableObject.cs:117
at Xamarin.Forms.Element.SetChildInheritedBindingContext (Xamarin.Forms.Element child, System.Object context) [0x00000] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\Element.cs:472
at Xamarin.Forms.Element.OnBindingContextChanged () [0x00021] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\Element.cs:322
at Xamarin.Forms.View.OnBindingContextChanged () [0x00042] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\View.cs:99
at Xamarin.Forms.BindableObject.SetInheritedBindingContext (Xamarin.Forms.BindableObject bindable, System.Object value) [0x00061] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\BindableObject.cs:118
at Xamarin.Forms.Element.SetChildInheritedBindingContext (Xamarin.Forms.Element child, System.Object context) [0x00000] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\Element.cs:472
at Xamarin.Forms.Element.OnBindingContextChanged () [0x00021] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\Element.cs:322
at Xamarin.Forms.View.OnBindingContextChanged () [0x00042] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\View.cs:99
at Xamarin.Forms.Grid.OnBindingContextChanged () [0x00006] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\Grid.cs:139
at Xamarin.Forms.BindableObject.SetInheritedBindingContext (Xamarin.Forms.BindableObject bindable, System.Object value) [0x00061] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\BindableObject.cs:118
at Xamarin.Forms.Element.SetChildInheritedBindingContext (Xamarin.Forms.Element child, System.Object context) [0x00000] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\Element.cs:472
at Xamarin.Forms.Element.OnBindingContextChanged () [0x00021] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\Element.cs:322
at Xamarin.Forms.View.OnBindingContextChanged () [0x00042] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\View.cs:99
at Xamarin.Forms.Grid.OnBindingContextChanged () [0x00006] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\Grid.cs:139
at Xamarin.Forms.BindableObject.SetInheritedBindingContext (Xamarin.Forms.BindableObject bindable, System.Object value) [0x00061] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\BindableObject.cs:118
at Xamarin.Forms.Element.SetChildInheritedBindingContext (Xamarin.Forms.Element child, System.Object context) [0x00000] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\Element.cs:472
at Xamarin.Forms.Element.OnBindingContextChanged () [0x00021] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\Element.cs:322
at Xamarin.Forms.Cell.OnBindingContextChanged () [0x00000] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\Cells\Cell.cs:117
at Xamarin.Forms.BindableObject.BindingContextPropertyBindingPropertyChanged (Xamarin.Forms.BindableObject bindable, System.Object oldvalue, System.Object newvalue) [0x0001b] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\BindableObject.cs:429
at Xamarin.Forms.BindableObject.SetValueActual (Xamarin.Forms.BindableProperty property, Xamarin.Forms.BindableObject+BindablePropertyContext context, System.Object value, System.Boolean currentlyApplying, Xamarin.Forms.BindableObject+SetValueFlags attributes, System.Boolean silent) [0x00108] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\BindableObject.cs:584
at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, Xamarin.Forms.BindableObject+SetValueFlags attributes, Xamarin.Forms.BindableObject+SetValuePrivateFlags privateAttributes) [0x0014b] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\BindableObject.cs:378
at Xamarin.Forms.BindableObject.SetValue (Xamarin.Forms.BindableProperty property, System.Object value, System.Boolean fromStyle, System.Boolean checkAccess) [0x0005f] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\BindableObject.cs:531
at Xamarin.Forms.BindableObject.SetValue (Xamarin.Forms.BindableProperty property, System.Object value) [0x00000] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\BindableObject.cs:83
at Xamarin.Forms.BindableObject.set_BindingContext (System.Object value) [0x00000] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\BindableObject.cs:24
at Xamarin.Forms.TemplatedItemsList`2+<UnhookItem>d__153[TView,TItem].MoveNext () [0x000a7] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Core\TemplatedItemsList.cs:1210
InnerException StackTrace:
at Realms.NativeException.ThrowIfNecessary (System.Func`2[T,TResult] overrider) [0x00014] in <fb8acf22c75e4f8ba1fe5f730039e63b>:0
at Realms.RowHandle.get_RowIndex () [0x00009] in <fb8acf22c75e4f8ba1fe5f730039e63b>:0
at Realms.RealmObject.GetObjectValue[T] (System.String propertyName) [0x00000] in <fb8acf22c75e4f8ba1fe5f730039e63b>:0
at TestProject.StockApp.Data.ManagedObjects.ArticleEntity.get_Article () [0x00006] in <bc12041acc564a39b37d8658934e3bc3>:0
at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (System.Reflection.MonoMethod,object,object[],System.Exception&)
at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00038] in /Users/builder/data/lanes/3818/3983064a/source/xamarin-macios/_ios-build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:305
It seems that the error occurs only when the Realm objects used in the ListView have relationships that were also displayed to the ListView cell.
For example, if I have a list of Dogs but in the cell I also show the Owner .FirstName then the crash occurs when I delete the selected dog item.
public class Dog : RealmObject
{
public string Name { get; set; }
public int Age { get; set; }
public Person Owner { get; set; }
}
public class Person: RealmObject
{
public string FirstName{ get; set; }
}
The list data source is linked to an observable collection which is populated with realm objects
How is that observable collection updated?
The stack trace is deep in Forms - looks like it is a quirk of how their code works - can you please send source to [email protected] and I will look at it.