Entity Framework inheritance and relationship

Question

I'm trying to implement a relationship(one-to-many) for my entities which use default TPH inheritance

public abstract class base
{
        public int Id { get; set; }
        ...
}

public class X : base
{
        public ApplicationUser User { get; set; }
       ...
}

public class Y : base
{
        public ApplicationUser User { get; set; }
       ...
}

public class ApplicationUser
{
        public string Name { get; set;}
       ...
        public ICollection<X> classX { get; set; }
        public ICollection<Y> classY { get; set; }
}

Everything works, but the problem is that Entity Framework creates two columns in the base table - User_Id and User_Id1. How can I map it so that there is only one column for the foreign key (User_Id) and depending on the content of the record in the Discriminator column (created by EF) the foreign key would be assigned to the appropriate entity?

Hey. Just an in general comment. "base" is a keyword. So its not an optimal name for a base class. "MyBaseClass" would be a better candidate for sample code. And real code..I would never name a class that. Does that make sense? docs.microsoft.com/en-us/dotnet/csharp/language-reference/… — granadaCoder

David Browne - Microsoft David Browne - Microsoft · Accepted Answer · 2018-09-07T13:54:15

How can I map it so that there is only one column for the foreign key (User_Id) and depending on the content of the record in the Discriminator column (created by EF) the foreign key would be assigned to the appropriate entity?

You can't. Thinking about it a bit I don't see any obvious reason why that feature couldn't be implemented. It just hasn't.

If you want X and Y to share an attribute, derive them both from and intermediate XYEntity type, and give ApplicationUser a single Navigation Property of type ICollection<XYEntity>.

Entity Framework inheritance and relationship

1 Answers