public class Post
{
    public int Id { get; set; }

    [Column(TypeName = "date")]
    public DateTime? PostedDate { get; set; }

    [Column(TypeName = "text")]
    public string Body { get; set; }

    public int UserId { get; set; }
    public virtual User User { get; set; }

    public Post()
    {
        Comments = new HashSet<PostComment>();
    }
}


public class ApplicationUser : IdentityUser
{
    public int Id { get; set; }

    [Column(TypeName = "date")]
    public DateTime RegistrationDate { get; set; }

    [Column(TypeName = "date")]
    public DateTime LastVisit { get; set; }

    public virtual ICollection<Post> Posts { get; set; }

    public ApplicationUser()
    {
        Users = new HashSet<User>();
    }
}

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

    public virtual DbSet<Post> Posts { get; set; }

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

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
      ...
    }
}