Deleting an Entity In Custom BindingList
Printed From: IdeaBlade
Category: DevForce
Forum Name: DevForce 2010
Forum Discription: For .NET 4.0
URL: http://www.ideablade.com/forum/forum_posts.asp?TID=2716
Printed Date: 30-Jul-2026 at 2:24am
Topic: Deleting an Entity In Custom BindingList
Posted By: Randar
Subject: Deleting an Entity In Custom BindingList
Date Posted: 25-May-2011 at 12:53pm
I am trying to be clever and creating my own BindingList, which handles the adding/deleting of entity logic. That way, when I bind it to simple UltraGrids (similar to DataGrids), they should delete themselves. See http://www.ideablade.com/forum/forum_posts.asp?TID=2712&title=editable-grid-controls for some additional info. The problem is, whenever I try to delete the entity via the aspect, I get an error I don't really understand.
Here is the key parts of the code:
''' <summary>
''' This class is a wrapper around BindingList, that is incorporated directly into the the EntityManager for new/delete operations.
''' </summary>
''' <typeparam name="T"></typeparam>
Public Class EntityBindingList(Of T)
Inherits BindingList(Of T)
''' <summary>
''' Removes the item at the specified index.
''' </summary>
''' <param name="index">The zero-based index of the item to remove.</param>
''' <exception cref="T:System.NotSupportedException">You are removing a newly added item and <see cref="P:System.ComponentModel.IBindingList.AllowRemove" /> is set to false. </exception>
Protected Overrides Sub RemoveItem(ByVal index As Integer)
OnRemovingItem(New RemoveItemEventArgs(Me(index)))
' Convert this to a entity so we can access the EntityAspect
Dim entityToRemove As Entity = TryCast(Me(index), IdeaBlade.EntityModel.Entity)
' Flag the entity to be deleted when the EntityManager is saved
entityToRemove.EntityAspect.Delete()
MyBase.RemoveItem(index)
End Sub
End Class
When stepping through the code, as soon as I try to call EntityAspect.Delete(), I get "Unable to delete the row: Cannot call BeginEdit() on Deleted entities." Which makes no sense since I can see through the watch window, it is still flagged as "Unchanged".
I tried to not Delete it, thinking it might change it under the hood, but no luck.
So what does the error mean? Or even better, how do I fix it?
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Replies:
Posted By: ting
Date Posted: 25-May-2011 at 4:26pm
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Before deleting an entity, it's good practice to remove it from any bound lists. What happens if you move MyBase.RemoveItem(index) before entityToRemove.EntityAspect.Delete()?
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