Question

I’m trying to query abstract entity using SqlQuery() method (code first).

public abstract class UserComment
{
    ... [internals]
}

public class BlogComment : UserComment
{
    ... [internals]
}

var result = Context.Database.SqlQuery<UserComment>(
                 @"select * from [UserComments] where ... [internals]",
                 new SqlParameter("user_id", user.Id));

This gives me error:

   System.ArgumentNullException: Value cannot be null.
   Parameter name: constructor

If I change abstract type to concrete..

Context.Database.SqlQuery<BlogComment>

…everything works fine.

Is it possible to query abstract class using raw queries?

Answer 1

I didn’t try it but I expect the answer is no. You cannot create instance of abstract class and that is exactly what EF is trying to do when materializing result set of the raw query.