Unable to add data while using Table Per Type Inheritance

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Hi. In my model, I have an entity called Person and Learner and Teacher inherit from Person. When I attempt to add data for a Learner as thus:

C#

using (var db = new SCSOMLAModelContext())
            {
                var learner = new Learner
                {
                    FirstName = firstName,
                    MiddleName = middleName,
                    LastName = lastName,
                    UserId = 1,
                    RegistrationNumber = registrationNumber
                };

                db.

            }

the context object "db", seem not to contain information about the inheritance types as thus:

C#

public class SCSOMLAModelContext : DbContext
    {
        public SCSOMLAModelContext();

        public virtual DbSet<Person> People { get; set; }
        public virtual DbSet<User> Users { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder);
    }

I am using Model First approach and without this entities (Learner and Teacher), I am unable to add data to them. In my database, I have this tables available as "People_Learner", and "People_Teacher".

Please assist on how to add data to this tables, I am totally stuck. And why are these two entities (Learner and Teacher) not on DbContext? I am using VS2013.

Posted 23-Nov-13 1:08am

Wamuti

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Er Daljeet Singh · Answer 1 · 2013-11-24T19:37:00

you should write like this..

C#

using (var db = new SCSOMLAModelContext())
            {
                var learner = new Learner
                {
                    FirstName = firstName,
                    MiddleName = middleName,
                    LastName = lastName,
                    UserId = 1,
                    RegistrationNumber = registrationNumber
                };

                db.Learners.AddObject(learner);
                db.SaveChanges();

            }

this will insert record to the Learner table.

Wamuti · Answer 2 · 2013-11-25T06:41:00

The problem is that, as I had said, Model First does not add the derived classes (Learner and Teacher) in DbContext. The changes I made for the DbContext inheriting class is this:

C#

public partial class SCSOMLAModelContext : DbContext
    {
        public SCSOMLAModelContext()
            : base("name=SCSOMLAModelContext")
        {
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Learner>().ToTable("User");
            modelBuilder.Entity<Teacher>().ToTable("Person");
        }

        public virtual DbSet<User> Users { get; set; }
        public virtual DbSet<Person> People { get; set; }
        public virtual DbSet<Learner> Learners { get; set; }
        public virtual DbSet<Teacher> Teachers { get; set; }
    }

It works! :-)

Unable to add data while using Table Per Type Inheritance

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