Asp.net identity entity framework database first approach with own table defintion

Question

I have below four tables

Role table

User table

Answer 1

Since you're using Microsoft.AspNet.Identity you should inherit your User from IdentityUser (namespace Microsoft.AspNet.Identity.EntityFramework).

Your classes should be defined like this:

USER

public class User : IdentityUser<int, UserLogin, UserRole, UserClaim>
{
}

ROLE

public class Role : IdentityRole<int, UserRole>
{
}

USER-ROLE

public class UserRole : IdentityUserRole<int>
{
}

USER-CLAIM

public class UserClaim : IdentityUserClaim<int>
{
}

USER-LOGIN

public class UserLogin : IdentityUserLogin<int>
{
}

You could extend the classes adding your own custom columns:

public class User : IdentityUser<int, UserLogin, UserRole, UserClaim>
{
    public string CompanyName { get; set; }
}

Now you have to define the stores:

public class UserStore:  UserStore<User, Role, int, UserLogin, UserRole, UserClaim>
{
    public UserStore(MyContext context)
        : base(context)
    {
    }
}

and then your database context, inheriting from IdentityDbContext:

public class MyContext : IdentityDbContext<User, Role, int, UserLogin, UserRole, UserClaim>
{
    public MyContext(): base("ConnectionString")
    {

    }
}

In your database context (MyContext) you must override OnModelCreating so that you can make your columns, change types, tables names etc etc:

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

        modelBuilder.Entity<MyUser>()
            .Property(p => p.Id)
            .HasColumnType("int")
            .IsRequired();

        modelBuilder.Entity<MyRole>()
            .Property(p => p.Id)
            .HasColumnType("int")
            .IsRequired();

        modelBuilder.Entity<MyUserRole>()
            .Property(p => p.RoleId)
            .HasColumnType("int")
            .IsRequired();

        modelBuilder.Entity<MyUserRole>()
            .Property(p => p.UserId)
            .HasColumnType("int")
            .IsRequired();

        modelBuilder.Entity<MyUserClaim>()
            .Property(p => p.Id)
            .HasColumnType("int")
            .IsRequired();

        modelBuilder.Entity<MyUserClaim>()
            .Property(p => p.UserId)
            .HasColumnType("int")
            .IsRequired();

        modelBuilder.Entity<MyUserLogin>()
            .Property(p => p.UserId)
            .HasColumnType("int")
            .IsRequired();

        modelBuilder.Entity<MyUser>()
            .ToTable("Users");

        modelBuilder.Entity<MyRole>()
            .ToTable("Roles");

        modelBuilder.Entity<MyUserRole>()
            .ToTable("UserRoles");

        modelBuilder.Entity<MyUserClaim>()
            .ToTable("UserClaims");

        modelBuilder.Entity<MyUserLogin>()
            .ToTable("UserLogins");

    }

Now you can use migrations to generate your tables.

I've update a github project to reflect your situations.

UPDATE:

If you want to customize names and types of your columns you simply have to give them a name:

modelBuilder.Entity<User>()
    .Property(p => p.Id)
    .HasColumnName("user_id")
    .HasColumnType("SMALLINT")
    .IsRequired();