Entity Framework: Remove and Add entities with same key in a single request

Question

I need to Remove and Add entities with the same primary key value in a single request, can anybody suggest me the solution?

Below is my sample code that gives the error: Violation of PRIMARY KEY constraint 'PK_Table'. Cannot insert duplicate key in object 'dbo.Table'.

context.Set<Entity>().Attach(existingEntityObj);
Entry(existingEntityObj).State = EntityState.Deleted;

context.Set<Entity>().Add(newEntityObj);
context.Entry<Entity>(newEntityObj).State = EntityState.Added;

context.SaveChanges();

Assume both the objects (existingEntityObj and newEntityObj) have the same value in the primary key property.

thanks in advance!!

Answer 1

You'll need to do two SaveChanges() calls in order to make this work. The problem here is that, while it appears you are first deleting the record and then adding a new one, the framework is actually doing the insert first.

The reason is because Entity Framework doesn't give you granular control over what orders the operations happen in. So your best bet is going to be to wrap the two in separate TransactionScope's which will let you control the individual transactions that are occurring.

You can read more here: https://blogs.msdn.microsoft.com/alexj/2009/01/11/savechangesfalse/