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[Solved] Binding to a Collection of different types throws InvalidCastException

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Tom asked on 11 Mar 2010, 12:13 PM

I've got a FruitsCollection object which I'm binding to from a RadGridView. In the collection are Fruit objects. This base class is derived by Apples and Bananas. I initialise the collection to contain two Apples, then try and add a Banana object and notify the GridView. This throws an exception:

System.InvalidCastException was unhandled by user code
Message="Unable to cast object of type 'SilverlightApplication3.Banana' to type 'SilverlightApplication3.Apple'."
StackTrace:
       at System.Linq.Enumerable.<CastIterator>d__b1`1.MoveNext()
       at Telerik.Windows.Data.QueryableCollectionView.PopulateInternalList(IQueryable view)
       at Telerik.Windows.Data.QueryableCollectionView.CreateInternalList()
       at Telerik.Windows.Data.QueryableCollectionView.EnsureInternalList()
       at Telerik.Windows.Data.QueryableCollectionView.get_InternalList()
       at Telerik.Windows.Data.QueryableCollectionView.get_IsEmpty()
       at Telerik.Windows.Controls.GridView.BaseItemsControl.OnItemCollectionChanged(Object sender, NotifyCollectionChangedEventArgs e)
       at System.Collections.Specialized.NotifyCollectionChangedEventHandler.Invoke(Object sender, NotifyCollectionChangedEventArgs e)
       at Telerik.Windows.Data.DataItemCollection.OnCollectionChanged(NotifyCollectionChangedEventArgs e)
       at Telerik.Windows.Data.DataItemCollection.Telerik.Windows.Data.IWeakEventListener<System.Collections.Specialized.NotifyCollectionChangedEventArgs>.ReceiveWeakEvent(Object sender, NotifyCollectionChangedEventArgs e)
       at Telerik.Windows.Data.WeakEvent.WeakListener`1.Handler(Object sender, TArgs args)
       at System.Collections.Specialized.NotifyCollectionChangedEventHandler.Invoke(Object sender, NotifyCollectionChangedEventArgs e)
       at Telerik.Windows.Data.QueryableCollectionView.OnCollectionChanged(NotifyCollectionChangedEventArgs args)
       at Telerik.Windows.Data.QueryableCollectionView.RefreshAndRaiseCollectionChanged(NotifyCollectionChangedEventArgs args)
       at Telerik.Windows.Data.QueryableCollectionView.OnSourceCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args)
       at Telerik.Windows.Data.QueryableCollectionView.Telerik.Windows.Data.IWeakEventListener<System.Collections.Specialized.NotifyCollectionChangedEventArgs>.ReceiveWeakEvent(Object sender, NotifyCollectionChangedEventArgs args)
       at Telerik.Windows.Data.WeakEvent.WeakListener`1.Handler(Object sender, TArgs args)
       at System.Collections.ObjectModel.ObservableCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs e)
       at System.Collections.ObjectModel.ObservableCollection`1.InsertItem(Int32 index, T item)
       at System.Collections.ObjectModel.Collection`1.Add(T item)
       at SilverlightApplication3.FruitCollection.AddBanana()
       at SilverlightApplication3.ViewModel.<get_AddCommand>b__1(Object o)
       at Microsoft.Practices.Composite.Presentation.Commands.DelegateCommand`1.Execute(T parameter)
       at Microsoft.Practices.Composite.Presentation.Commands.DelegateCommand`1.System.Windows.Input.ICommand.Execute(Object parameter)
       at Microsoft.Practices.Composite.Presentation.Commands.CommandBehaviorBase`1.ExecuteCommand()
       at Microsoft.Practices.Composite.Presentation.Commands.ButtonBaseClickCommandBehavior.OnClick(Object sender, RoutedEventArgs e)
       at System.Windows.Controls.Primitives.ButtonBase.OnClick()
       at System.Windows.Controls.Button.OnClick()
       at System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp(MouseButtonEventArgs e)
       at System.Windows.Controls.Control.OnMouseLeftButtonUp(Control ctrl, EventArgs e)
       at MS.Internal.JoltHelper.FireEvent(IntPtr unmanagedObj, IntPtr unmanagedObjArgs, Int32 argsTypeIndex, String eventName)
InnerException:

[Solved] Binding to a Collection of different types throws InvalidCastException

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