The ObjectStateManager does not contain an ObjectStateEntry with a reference to an object

Question

I thought I understood EF, particularly in terms of excrutiatingly simple CRUD, but I may be wrong.

I have an ObjectContext/Repository pattern, and in this case a VatCode entity which has a collection of VatRates.

VatCode 1--* VatRate

I want to provide the functionality for CRUDing these entities. This is in a WPF application, and is operating "disconnected" in that I am not holding DB connections open unnecassarily. I prefer the in/out method of database access. This is shown in the following integration test:

    [TestMethod()]
    public void AddVatRateAndSaveVatCodeTest()
    {
        VatCode vatCode=null;
        DateTime expectedDateFrom = DateTime.Now.AddDays(1).Date;
        using (SopEntities sopEntities = EntitiesFactory.Create(Properties.Resources.ConnectionString))
        {
            VatRepository target = new VatRepository(sopEntities);
            vatCode = target.SingleOrDefault(q => q.Key == "X4");
            Assert.IsNotNull(vatCode);
        }

        // mimick offline editing/disconnect

        using (SopEntities sopEntities = EntitiesFactory.Create(Properties.Resources.ConnectionString))
        {
            VatRepository target = new VatRepository(sopEntities);


            vatCode.VatRates.Add(new VatRate()
                {
                    DateFrom=expectedDateFrom,
                    Rate=20
                });
            target.Attach(vatCode);
            target.SaveChanges();
        }

        using (SopEntities sopEntities=EntitiesFactory.Create(Properties.Resources.ConnectionString))
        {
            VatRepository vatRepository=new VatRepository(sopEntities);
            VatCode actual=vatRepository.SingleOrDefault(q=>q.Key=="X3");
            Assert.IsNotNull(actual);
            Assert.AreEqual(vatCode.VatRates.Count,actual.VatRates.Count);
            Assert.AreEqual(expectedDateFrom,actual.VatRates.OrderBy(q=>q.DateFrom).Last().DateFrom);
        }
    }

The code is simple. It retrieves a known existing entity and assigns it to vatCode. This entity is then passed around in the ViewModel on the UI, and re-saved. In this test, I mimmick this by opening a new context. This is exactly how I would in the UI, so I am proving it here.

However, on calling the Attach() method of the vatRepository, which has the following method body:

    public void Attach(TEntity entity)
    {
        if (entity == null)
            throw new ArgumentNullException("entity");

        _context.ObjectStateManager.ChangeObjectState(entity, System.Data.EntityState.Modified); // exception here
        _objectSet.Attach(entity);
    }

I get the exception below on the ChangeObjectState method (which I call because the entity was disconnected from the original context scope).

System.InvalidOperationException was unhandled by user code
Message=The ObjectStateManager does not contain an ObjectStateEntry with a reference to an object of type 'Mac.Sop.Core.Data.VatCode'.

I did consider that maybe my XML in the EF model was not correct (considering reference to 'Mac.Sop.Core.Data.VatCode'), but looking through it I cannot find any issues and these entities follow similar patterns with my other entities.

Update: My EF model. I can't find any reference to 'Mac.Sop.Core.Data.VatCode':

This needs to work in this disconnected fashion and it must be possible as WCF/ASP.NET implementations of this pattern obviously exist!

Eranga · Accepted Answer

Swap the Attach and ChangeObjectState lines because you need to add the entity to ObjectStateManager in order to change the state.

public void Attach(TEntity entity)
{
    if (entity == null)
        throw new ArgumentNullException("entity");

    _objectSet.Attach(entity);
    _context.ObjectStateManager.ChangeObjectState(entity, EntityState.Modified);        
}

The ObjectStateManager does not contain an ObjectStateEntry with a reference to an object

Answers (1)

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