Sql – “An attempt has been made to Attach or Add an entity that is not new…” after calling ObjectChangeConflict.Resolve()

linq-to-sql

I have a pair of classes which, when updated together as shown below are guaranteed to cause a ChangeConflictException because a trigger on child object table updates a value on the parent object record. I believe I am following the correct procedure for resolving the conflict and resubmitting the update, but upon calling the second db.SubmitChanges (or even if I call db.GetChangeSet()), I get the "an attempt has been made to attach or add an entity that is not new blah blah blah" error.

        using (SurveyDB db = new SurveyDB())
        {
            Parent p = db.Parents.Single(t => t.Id == 1);
            p.Children.Add(new Child {...});
            p.SomeProperty = "new value";
            try
            {
                db.SubmitChanges();
            }
            catch (ChangeConflictException e)
            {
                foreach (ObjectChangeConflict o in db.ChangeConflicts)
                    o.Resolve(RefreshMode.KeepChanges, true);

                db.SubmitChanges(ConflictMode.FailOnFirstConflict);
            }
        }

Any help greatly appreciated.

Best Answer

The resolution for me was to set dbml "Update Check" property for the fields set by the trigger to "Never" - this works for the situation where the application never modifies those fields. Otherwise, I'd have had to call SubmitChanges twice - once after editing the parent object and then again after adding the child object (followed by retrieving the parent-object again).

Related Solutions

Sql – “An attempt has been made to Attach or Add an entity that is not new, perhaps having been loaded from another DataContext. This is not supported.”

I create a class called applicationController which derives from Controller. Then i make all of my controller classes derive from this. The applicationController class has a constrcutor which creates a new instance of my repository (or datacontext in your instance) which is used throughout the application:

     public class ApplicationController : Controller
     {
          private VeriTabanDataContext _datacontext;

          public ApplicationController() : this(new VeriTabanDataContext())
          {
          }

          public ApplicationController(VeriTabanDataContext datacontext)
          {
               _datacontext = datacontext;
          }

          Public VeriTabanDataContext DataContext
          {
               get { return _datacontext; } 
          }
     }

Then you can use this in all of your controllers

public class MyController : ApplicationController
{
     public ActionResult Complete()        
     {            
           DataContext.Persons.InsertOnSubmit(_person);              
           DataContext.SubmitChanges();                
           return View(_person);            
     }
}

Not on my PC with VS installed at the moment so not tested this code....

Hope this resolves the issue -Mark

C# – LINQ TO SQL error: An attempt has been made to Attach or Add an entity that is not new

Looks like obj was built using a different dataContext and that needs to be created using the same dataContext rather than instantiating a new one.

A quick solution might be to pass in a dataContext rather than instantiating a new one inside this method.

Best Answer

Related Solutions

Sql – “An attempt has been made to Attach or Add an entity that is not new, perhaps having been loaded from another DataContext. This is not supported.”

C# – LINQ TO SQL error: An attempt has been made to Attach or Add an entity that is not new

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