Okay, MVC is becoming a major headache to learn and it shouldn't be so difficult! I am using the User Accounts in MVC. I have been able to create user profile information in a foreign table, but I am having a major hard time extracting information from this foreign table to compare at account registration, to ensure it is not already in the database. If it exists in the database (MSSQL), then to show a model error. If the value does not exist, register the account.

First thing I did was to create a class file called TenantInfo.cs under the models folder with the following data:

Code:
using Microsoft.AspNet.Identity.EntityFramework;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity;

public class Tenant : IdentityUser
{
public virtual TenantInfo TenantInfo { get; set; }
}

[Table("TenantInfo")]
public class TenantInfo
{
[Column("TenantInfoID")]
public int TenantInfoID { get; set; }

[Column("CompanyName")]
[DataType(DataType.Text)]
[Display(Name = "Company Name")]
[MinLength(4), MaxLength(250), StringLength(250, ErrorMessage = "The {0} must be from {1} to {2} characters long.", MinimumLength = 4)]
[Index("IX_TenantInfo_CompanyName", IsUnique = true)]
[Required(AllowEmptyStrings = false,
          ErrorMessage = "The {0} is required. Please enter in a valid {0}."),
          ConcurrencyCheck]
[DisplayFormat(ConvertEmptyStringToNull = false)]
public string CompanyName { get; set; }

[Column("FirstName")]
[DataType(DataType.Text)]
[Display(Name = "First Name")]
[MinLength(1), MaxLength(25), StringLength(25, ErrorMessage = "The {0} must be from {1} to {2} characters long.", MinimumLength = 1)]
[Required(AllowEmptyStrings = false,
          ErrorMessage = "The {0} is required. Please enter in a valid {0}."),
          ConcurrencyCheck]
public string FirstName { get; set; }

[Column("MiddleName")]
[DataType(DataType.Text)]
[Display(Name = "Middle Name")]
[MinLength(0), MaxLength(25), StringLength(25, ErrorMessage = "The {0} must be from {1} to {2} characters long.", MinimumLength = 0)]
[ConcurrencyCheck]
[DisplayFormat(ConvertEmptyStringToNull = true)]
public string MiddleName { get; set; }

[Column("LastName")]
[DataType(DataType.Text)]
[Display(Name = "Last Name")]
[MinLength(1), MaxLength(25), StringLength(25, ErrorMessage = "The {0} must be from {1} to {2} characters long.", MinimumLength = 1)]
[Required(AllowEmptyStrings = false,
          ErrorMessage = "The {0} is required. Please enter in a valid {0}."),
          ConcurrencyCheck]
public string LastName { get; set; }

public class TenantDbContext : IdentityDbContext<Tenant>
{
    public TenantDbContext() : base("DefaultConnection") { }
    public DbSet<TenantInfo> TenantInfo { get; set; }
}
}
I then went into AccountController.cs and updated the Register action with the following:

Code:
var user = new ApplicationUser
            {
                TenantInfo = new TenantInfo
                {
                    CompanyName = model.CompanyName,
                    FirstName = model.FirstName,
                    MiddleName = model.MiddleName,
                    LastName = model.LastName,
                },

                UserName = model.Email,
                Email = model.Email
            };
The respective register CSHTML and RegisterViewModel was updated with the additional fields.

Within the IdentityModels.cs file, under ApplicationUser, I added the following:

Code:
 [Column("TenantInfoID")]
    public int TenantInfoID { get; set; }
    [ForeignKey("TenantInfoID")]
    public virtual TenantInfo TenantInfo { get; set; }
I then updated the ApplicationDbContext within IdentityModels.cs to the following:

Code:
public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
    {
    public ApplicationDbContext()
        : base("DefaultConnection", throwIfV1Schema: false)
    {
    }

    public static ApplicationDbContext Create()
    {
        return new ApplicationDbContext();
    }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        modelBuilder.Entity<ApplicationUser>()
                    .HasRequired<TenantInfo>(ti => ti.TenantInfo);

        modelBuilder.Entity<ApplicationUser>()
                    .ToTable("Users")
                    .Property(p => p.Id)
                    .HasColumnName("UserID");

        modelBuilder.Entity<ApplicationUser>()
                    .Property(p => p.Email)
                    .HasColumnName("EmailAddress");

        modelBuilder.Entity<ApplicationUser>()
                    .Property(p => p.UserName)
                    .HasColumnName("Username");

        modelBuilder.Entity<IdentityRole>()
                    .ToTable("Roles")
                    .Property(p => p.Id)
                    .HasColumnName("RoleID");

        modelBuilder.Entity<IdentityUserRole>()
                    .ToTable("UserRoles")
                    .Property(p => p.UserId)
                    .HasColumnName("UserID");

        modelBuilder.Entity<IdentityUserRole>()
                    .Property(p => p.RoleId)
                    .HasColumnName("RoleID");

        modelBuilder.Entity<IdentityUserClaim>()
                    .ToTable("UserClaims")
                    .Property(p => p.UserId)
                    .HasColumnName("UserID");

        modelBuilder.Entity<IdentityUserClaim>()
                    .Property(p => p.Id)
                    .HasColumnName("UserClaimsID");

        modelBuilder.Entity<IdentityUserLogin>()
                    .ToTable("UserLogins")
                    .Property(p => p.UserId)
                    .HasColumnName("UserID");

        modelBuilder.Conventions
                    .Remove<PluralizingTableNameConvention>();

        modelBuilder.Conventions
                    .Remove<OneToManyCascadeDeleteConvention>();
    }

    public DbSet<TenantInfo> TenantInfo { get; set; }
}
My issue right now, is that I am trying to prevent duplicate Company Names from being registered. I have no idea how this is checked. Been searching for days online and getting no where fast.

Right now, if I register a second user with the same company name, I get the error about the unique constraint, which is expected. I also tried catching the SQLException and checking to see if the error contains the first part of the exception and it still shows the error when trying to register. It should show a model error if the company name already exists, but it doesn't. Some people have said to use the [Remote] DataAnnotation, but this does not make sense to me at all.

Any suggestions would be appreciated.