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POCO Merge Failure after Save
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rhaney View Drop Down
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Joined: 06-Jul-2010
Location: Orange, CA
Posts: 12 		Post Options Post Options   Quote rhaney Quote  Post ReplyReply Direct Link To This Post Topic: POCO Merge Failure after Save
    Posted: 07-Sep-2010 at 2:15pm
I've created a simple POCO class to support user defined fields in my DevForce application.  I can get instances of the POCO class into the UI, and push updates back to the server via the SaveChanges method, but an exception is always raised on the client side after my PocoSaveAdapter executes.
 
My POCO object is pretty simple:
 
CustomField
  int : Id
  string : Name
  string : Value
 
Id is marked with the [Key] attribute.
 
Is there something I am missing?
 
Here is the exception:
 
IdeaBlade.EntityModel.EntityManagerSaveException: EntityManager merge failure: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at IdeaBlade.Core.MemberInfoFns.BuildPropertySet(PropertyInfo property)
   at IdeaBlade.EntityModel.EntityProperty.get_SetFunc()
   at IdeaBlade.EntityModel.PocoEntityWrapper.CopyValues(Object sourceEntity, Object destEntity)
   at IdeaBlade.EntityModel.PocoEntityWrapper.ReplaceCurrentOnLoadCore(EntityWrapper sourceWrapper)
   at IdeaBlade.EntityModel.EntityWrapper.ReplaceCurrentOnLoad(EntityWrapper sourceEntity)
   at IdeaBlade.EntityModel.EntityWrapper.LoadEntity(EntityWrapper sourceWrapper, MergeStrategy mergeStrategy)
   at IdeaBlade.EntityModel.EntityGroup.LoadEntity(EntityWrapper sourceWrapper, MergeStrategy mergeStrategy, Boolean& rowUpdated)
   at IdeaBlade.EntityModel.EntityMerger.MergeEntityCore(EntityWrapper sourceWrapper, EntityGroup targetEntityGroup)
   at IdeaBlade.EntityModel.EntityMerger.MergeEntity(EntityWrapper sourceWrapper, EntityGroup targetEntityGroup, NavigationContext context)
   at IdeaBlade.EntityModel.EntityMerger.<>c__DisplayClass1.<MergeEntities>b__0(EntityWrapper sourceWrapper)
   at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at IdeaBlade.EntityModel.EntityMerger.Merge(IEnumerable`1 sourceEntityWrappersGroupedByType, NavigationContext context)
   at IdeaBlade.EntityModel.EntityMerger.Merge(EntityManager targetManager, IEnumerable`1 sourceEntityWrappersGroupedByType, MergeStrategy mergeStrategy, MergeType mergeType)
   at IdeaBlade.EntityModel.EntityManager.SaveEntitiesPostProcessing(SaveWorkState workState)
   --- End of inner exception stack trace ---
   at IdeaBlade.EntityModel.AsyncProcessor`1.<>c__DisplayClass2.<.ctor>b__0(TArgs args)
   at IdeaBlade.EntityModel.AsyncProcessor`1.Signal()
   at IdeaBlade.EntityModel.AsyncProcessor`1.<Execute>b__5(Object x)    
Line: 56
Char: 13
Code: 0
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rhaney View Drop Down
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Joined: 06-Jul-2010
Location: Orange, CA
Posts: 12 		Post Options Post Options   Quote rhaney Quote  Post ReplyReply Direct Link To This Post Posted: 07-Sep-2010 at 2:17pm
FYI, this exception is raised in 6.0.4 and 6.0.5.
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davidklitzke View Drop Down
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Joined: 14-Jun-2007
Posts: 715 		Post Options Post Options   Quote davidklitzke Quote  Post ReplyReply Direct Link To This Post Posted: 08-Sep-2010 at 11:28am
Have you initialized the value of the id field?
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rhaney View Drop Down
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Posts: 12 		Post Options Post Options   Quote rhaney Quote  Post ReplyReply Direct Link To This Post Posted: 08-Sep-2010 at 12:07pm
Yes, the correct entity is updated during the save procedure in my PocoSaveAdapter class.
 
I can retrieve these POCO objects, modify them at the client, verify the entity state has changed, and persist the changes via the SaveChanges method.  At some point after the changes have been saved, the EM throws an exception on the client side (see the above exception).
 
I have a method defined as follows:
 
public void UpdateCustomField(CustomField current, CustomField original)
 
If I set a breakpoint at the beginning of this method, both "current" and "original" are fully populated objects, with the same ID.  This method executes without exceptions.  After updating and receiving the exception, if I restart my application I can pull up the entity and verify the changes were persisted.
 
The DevForce internal post save client-side merge operation is failing for POCO objects only.  If I don't modify a POCO object, everything works as expected.
 
It might be worth noting that I couldn't get an EntityServerPocoSaveAdapter implementation to be discovered, but the convention based approach outlined in the wiki at http://drc.ideablade.com/xwiki/bin/view/Documentation/POCOSupportInDevForce worked.
 
I'd prefer the EntityServerPocoSaveAdapter approach, due to the BeforeSave and AfterSave overrides.
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