New Posts New Posts RSS Feed: Entity exists when adding
  FAQ FAQ  Forum Search   Calendar   Register Register  Login Login

Entity exists when adding
 Post Reply Post Reply
Author
  Share Topic Share Topic  Topic Search Topic Search  Topic Options Topic Options
GeorgeB View Drop Down
Groupie
Groupie


Joined: 03-May-2010
Posts: 66 		Post Options Post Options   Quote GeorgeB Quote  Post ReplyReply Direct Link To This Post Topic: Entity exists when adding
    Posted: 16-Jun-2011 at 11:09am
Hi
 
I'm using DevForce 6.1 with Silverlight.
 
I have a single instance of EntityManager. I create a new entity, add it to the manager and in some instances I get this error:-
 
An entity with this key: TrackingEvent: -100 already exists in this EntityManager
 
In my repository I have (nothing really fancy - I'm using INT in SQL Server as a IdentityColumn)
 public TrackingEvent CreateTrackingEvent()
        {
            var aTrackingEvent = Manager.CreateEntity<TrackingEvent>();
            Manager.GenerateId(aTrackingEvent, TrackingEvent.PropertyMetadata.TrackingEventID);
            Manager.AddEntity(aTrackingEvent);
            return aTrackingEvent;
        }
Once I've assigned values to all the fields, I do a SaveAsync().
It's possible that the CreateTrackingEvent may get called at the same time but I can't stop that (nature of the application). 
Surely between the GenerateId and AddEntity, the EM can keep the ID's unique? 
Do I need create my own IdGenerator?
Thanks
George
Back to Top
kimj View Drop Down
IdeaBlade
IdeaBlade
Avatar

Joined: 09-May-2007
Posts: 1391 		Post Options Post Options   Quote kimj Quote  Post ReplyReply Direct Link To This Post Posted: 16-Jun-2011 at 5:18pm
Hi George,
 
The EntityManager is not designed to be thread safe, so if you are finding that the CreateTrackingEvent can be called simultaneously from two separate threads then you should lock around the logic in the method.  Eg,
 
lock (_aLockObject) {
  ... create and add entity
}
 
If that doesn't fix the problem, then it's not a threading issue and we'll need to get more information on what's going on within the application.
 
 
Back to Top
GeorgeB View Drop Down
Groupie
Groupie


Joined: 03-May-2010
Posts: 66 		Post Options Post Options   Quote GeorgeB Quote  Post ReplyReply Direct Link To This Post Posted: 20-Jun-2011 at 10:21pm
Hi Kim
 
Okay totally my problem.
 
When testing with single a record coming in everything worked but when multiple records were coming in (and they could be duplicated), I was doing an async check to see if the record already existed, it was possible in some cases for me to be adding a new record whilst still waiting for the first check to come back.
 
My system is a lot more complex that what I have described above, but that is the big picture.
 
Thanks for the help.
 
Kr
George
Back to Top
 Post Reply Post Reply

Forum Jump Forum Permissions View Drop Down