EF6 AutoMapper6 Parent/Child different behavior - entity-framework-6

Question

I just updated an entire WCF app from EF4 / AutoMapper 1.1 to EF6 / AutoMapper 6.0.0.2 and the behavior is not completely the same.
This doesn't work for me :
Entity Framework - Add Child Entity
Before :
child.Parent = parentObject
OR
parentObject.Children.Add(child)
had the same result in real time (while debugging == before SaveChanges), so I decided to use child.Parent = parentObject for the readability. child.Parent = parentObject added a child in parentObject automatically. The child was also added to the db.
Now : child.Parent = parentObject is not enough anymore (child is not added in the db), I have to add parentObject.Children.Add(child). Sometimes I need the link child.Parent = parentObject, so I have to write both lines. Can someone explain to me why it does not work anymore ?
Also :
I could write before :
Mapper.CreateMap< Patient, PATIENTENTITY >()
.ForMember(dest => dest.Gender, opt => opt.ResolveUsing< PatientGenderResolver >())
.ForMember(dest => dest.REF_GENDER, opt => opt.Ignore())
where dest.Gender is the PK(int) and PatientGenderResolver find the id(int) of the Gender in the table REF_GENDER. This mapping was enough to set PATIENTENTITY.REF_GENDER in real time thanks to the Id resolver.
Now the id is set but PATIENTENTITY.REF_GENDER remains null.
Also I tried to set directly PATIENTENTITY.REF_GENDER with a resolver but it add a Gender in the table REF_GENDER...
So again, can someone explain to me why it does not work anymore ?
EDIT
Some precisions :
Before :
patientEntity = Mapper.PatientToEntity(patientModel);
//patientEntity.REF_GENDER is null
Context.PATIENTENTITIES.AddObject(patientEntity);
//patientEntity.REF_GENDER is set !
Context.SaveChanges();
Now :
patientEntity = Mapper.PatientToEntity(patientModel);
//patientEntity.REF_GENDER is null
Context.PATIENTS.Add(patientEntity);
//patientEntity.REF_GENDER is still null !
//patientEntity.REF_GENDER = Context.REF_GENDER.Find(patientEntity.Gender);//I am obliged to add this line everywhere for every REF !
Context.SaveChanges();
My guess is that the two problems I have are related
EDIT
I just go back in my project. I now have EF6 and Automapper 1.1.
The problems are exactly the sames so I guess Automapper is not involved.
EDIT
I get around the REF_GENDER issue with
patientEntity = Mapper.PatientToEntity(patientModel, Context);
public PATIENT PatientToEntity(Patient patient, EntityContainer context)
{
PATIENT entity = AutoMapper.Mapper.Map<Patient, PATIENT>(patient);
if (patient.Id == null || patient.Id == Guid.Empty)
entity.PatientId = Guid.NewGuid();
else
entity.PatientId = patient.Id;
entity.REF_GENDER = context.REF_GENDER.Find(entity.Gender);
return entity;
}
Apparently, the context has to be the same otherwise a new REF_GENDER is added to the db

Answer 1

You don't mention it explicitly, but you didn't only move from EF 4 to 6, but also from ObjectContext to DbContext. That's a tremendous difference in behavior of the entity classes.
In the ObjectContext API the generated entity classes were stuffed with code that cooperated closely with the context they were involved in. A reference property like child.Parent would look like:
public Parent Parent
{
get
{
return ((IEntityWithRelationships)this).RelationshipManager.GetRelatedReference<Parent>("model.FK_Child_Parent", "Parent").Value;
}
set
{
((IEntityWithRelationships)this).RelationshipManager.GetRelatedReference<Parent>("model.FK_Child_Parent", "Parent").Value = value;
}
}
So setting this property is setting the Value property of an EntityReference<Parent>. EF4.1's code isn't public, so we can only guess what happens inside. One thing is clear: it changes childs state into Added -- if child wasn't yet attached to the context.
Fortunately EF abandoned this rigid vendor lock-in when it released the DbContext API (in EF 4.1 no less). Now this generated property isn't anything but an auto-property:
public Parent Parent { get; set; }
This made it much easier to unify the database-first and code-first modes of working with EF. In fact, both code-first and database-first entity classes were POCOs now.
The price (if you like) is that EF can't keep as close a track of everything that happens as it could before. Before, all entity classes inherited from EntityObject, and EF could keep track of all of their interactions. The statement...
child.Parent = parentObject;
would draw the yet unknown child into the context through the attached parentObject.
Now, when someone sets child.Parent, no one but child knows what happened, not even Parent. Which means: there is no way whatsoever for EF to become aware of this change when its change tracker executes DetectChanges (as it does very frequently).
That's why using DbContext you have to add a new child to the context yourself, either by explicitly setting its state, or adding it to context.Children. Or by adding it to parent.Children, which is a change the change tracker can detect, if parent is attached.