Base classes and parent/child relations in Entity Framework Code First

Question

Hi I've run into a problem with Parent/Child Relations between abstract baseclasses and their implementations

public class SuperParent
{
    public ICollection<Parent> ParentList { get; set; }
}

public abstract class Parent
{
    public int Id { get; set; }
    public string Title { get; set; }
}

public abstract class ParentExtended : Parent
{
    public ICollection<ChildClass> ChildClassList { get; set; }
}

public class RealClass : ParentExtended
{

}

public class ChildClass
{
    public int Id { get; set; }
    public Parent Parent { get; set; }
}

DBContext looks as follows:

    public DbSet<SuperParent> SuperParents { get; set; }
    public DbSet<Parent> Parents { get; set; }
    public DbSet<ChildClass> ChildClasses { get; set; }

Example code

    SuperParent sp = new SuperParent();
    sp.ParentList = new List<Parent>();


    RealClass parent = new RealClass();
    parent.ChildClassList = new List<ChildClass>();
    parent.ChildClassList.Add(new ChildClass());

    sp.ParentList.Add(parent);

Results in the database table ChildClass with columns

• Id
• Parentid(FK)
• ParentExtendedId(FK)

where ParentId is always null, parentExtendedId is filled with the correct Id but unwanted.

My question is this the way to go and how can i give childclass Parent as a parent and not ParentExtended

Answer 1

I found the answer myself and it's rather easy:) Decorate the childlist in the abstract class ParentExtended with a data annotation that tells the class what the inverse property within the child is.

So in my example:

public abstract class ParentExtended : Parent  
{  
   [InverseProperty("Parent")]    
   public ICollection<ChildClass> ChildClassList { get; set; }  
}

With creates a pointer to back to Realclass but in the variable named Parent