Adding object to database using table-per-type inheritance in Mvc 4

Question

I have a class Landlord that inherits from UserProfile using table-per-type inheritance.

When a new user registers on the application, they enter some criteria and select the type of account they want, either Landlord or Tenant.

Here's my AccountController/Register method:

public ActionResult Register(RegisterModel model)
    {
        if (ModelState.IsValid)
        {
            // Attempt to register the user
            try
            {
                WebSecurity.CreateUserAndAccount(model.UserName, model.Password,
                                            new
                                            {
                                                Email = model.Email,
                                                FirstName = model.FirstName,
                                                LastName = model.LastName,
                                                AccountType = model.AccountType.ToString()
                                            },
                                            false);

                // Add user to role that corresponds with selected account type
                if (model.AccountType == AccountType.Tenant)
                {
                    try
                    {
                        Roles.AddUserToRole(model.UserName, "Tenant");

                        using (var db = new LetLordContext())
                        {
                            var tenant = db.UserProfile.Create<Tenant>();

                            tenant.TenantAge = null;
                            tenant.TenantGroupMembers = null;
                            tenant.UserId = WebSecurity.CurrentUserId;
                            tenant.UserName = model.UserName;
                            // more properties associated with tenant
                            // ...

                            db.UserProfile.Add(tenant);
                            db.SaveChanges();
                        }

                    }
                    catch (ArgumentException e)
                    {
                        ModelState.AddModelError("Unable to add user to role", e);
                    }
                }
                if (model.AccountType == AccountType.Landlord)
                {
                    try
                    {
                        Roles.AddUserToRole(model.UserName, "Landlord");

                        using (var db = new LetLordContext())
                        {
                            var landlord = db.UserProfile.Create<Landlord>();

                            // same idea as adding a tenant
                        }
                    }
                    catch (ArgumentException e)
                    {
                        ModelState.AddModelError("Unable to add user to role", e);
                    }
                }

                return RedirectToAction("Confirm", "Home");
            }
            catch (MembershipCreateUserException e)
            {
                ModelState.AddModelError("", ErrorCodeToString(e.StatusCode));
            }
        }

        // If we got this far, something failed, redisplay form
        return View(model);
    }

As an example, if I selected Tenant as the desired account type when registering, WebSecurity.CreateUserAndAccount would add a user into the UserProfile table, correctly, with say a UserProfileId of 1.

Then, if (model.AccountType == AccountType.Tenant) would see that the selected account type is Tenant, add the user to that role, with a UserProfileId of 1 and a RoleId of 1. Within this if-statement, because selected role is Tenant, I create a new Tenant like so: var tenant = db.UserProfile.Create<Tenant>(); and it is saved to the database (with correct UserProfileID as the PK).

The problem: Two UserProfile entities (two rows) are being added to the UserProfile table each time I try to register ONE user. I understand that this is probably due to the fact that I am calling WebSecurity.CreateUserAndAccount AND I'm creating a new Tenant object.

How do I avoid this situation?

How do I add the model being used in WebSecurity.CreateUserAndAccount into UserProfile table and Tenant table ONCE?

Answer 1

Instead of calling WebSecurity.CreateUserAndAccount() and create the UserProfile subclass Tenent or Landlord respectively, which results in a duplicate entry in the UserProfile table, you can just create the subclass (providing also the values for the UserProfile) and then call the method WebSecurity.CreateAccount().

Here is how I solved the problem (my subclass is called Physician):

In AccountModels I added the sublass using table-per-type inheritance:

public class UsersContext : DbContext
{
    public UsersContext()
        : base("DefaultConnection")
    {
    }

    public DbSet<UserProfile> UserProfiles { get; set; }
    public DbSet<Physician> Physicians { get; set; }
}

[Table("UserProfile")]
public class UserProfile
{
    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int UserId { get; set; }
    public string UserName { get; set; }
}

[Table("Physicians")]
public class Physician : UserProfile
{
    public Guid PhysicianGUID { get; set; }
    public string Name { get; set; }
}

In the AccountController/Register method:

if (ModelState.IsValid)
        {
            // Attempt to register the user
            try
            {
                using( UsersContext dbContext = new UsersContext()){
                    dbContext.Physicians.Add(new Physician { UserName = model.UserName, Name = "testDoctor", PhysicianGUID = Guid.NewGuid() });
                    dbContext.SaveChanges();
                }
                WebSecurity.CreateAccount(model.UserName, model.Password);
                WebSecurity.Login(model.UserName, model.Password);
                return RedirectToAction("Index", "Home");
            }
            catch (MembershipCreateUserException e)
            {
                ModelState.AddModelError("", ErrorCodeToString(e.StatusCode));
            }
        }

Answer 2

In this instance you would not create both a UserProfile and a Tenant or Landlord. Once the Entity is created the entity type cannot be changed (even to extend it to a subtype). So in your case, you only need to skip the step of creating the UserProfile and just create and save either the Tenant or the Landlord entity that inherits it.

More info linked from Option 1 of my answer to this question: Code First TPT Inheritance - How can I supply the foreign key instead of EF creating the parent row for me?