Changing Inherited Types in Entity Framework

Question

I see there is a similar question asked here but I don't think it was very clear so I'm creating another : Entity Framework: Inheritance, change object type

I have an Entity Student that inherits from an Entity Person.

At some point a Person could become a Student.

Is there any way in Entity Framework 4 to handle this without a stored procedure or creating a new entity.

Chitter

This is a broken object model. In OOP, instances cannot change type. The EF does not add this feature to C#/.NET. You should use composition, not inheritance, for this. – Horn

I was under the impression that it was down to whether a Student IS a Person or whether a Student HAS a Person. Perhaps you could point me to a link where this is defined? – Chitter

An object can only have one type. So you can't make a type RedDog and also have a type BigDog, because a Dog can be both big and red (Clifford). I wrote about this issue here: blogs.teamb.com/craigstuntz/2008/07/17/37825 – Horn

I see this is an old post, based on EF4. Does this limitation yet exists in the last version of Entity (EF6) ? – Hurtless

Answer 1

No. The EF inheritance does not support this scenario. The best way to create a Student for an existing Person is to use a stored procedure.
Please note that this is not a stored procedure that is wired up to the Student entity through mappings, but a separate one that can be called explicitly from code. Ideally it would be a SP that takes a PersonID as a parameter, inserts a new row into the Student table using that PersonID, and then returns a complete Student so that it can be used immidiately.

Sexology

Just burned by this. There goes an hour I will never get back! – Sherlene