Code first one to one foreign key - ef-code-first

Question

I have two model class, where I want to make one-to-one relation. When I make migration, I get an error:
The ALTER TABLE statement conflicted with the FOREIGN KEY constraint
"FK_dbo.Uzytkownik_dbo.UserProfile_UserId". The conflict occurred in
database "db_wydarzenia", table "dbo.UserProfile", column 'UserId'.
[Table("UserProfile")]
public class UserProfile
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int UserId { get; set; }
public string UserName { get; set; }
}
[Table("Uzytkownik")]
public class Uzytkownik
{
[Key]
public int UzytkownikID { get; set; }
public int UserId { get; set; }
public string Imie { get; set; }
public string Nazwisko { get; set; }
public string Telefon { get; set; }
public string Email { get; set; }
[ForeignKey("UserId")]
public UserProfile UserProfile { get; set; }
}
EDIT:
Problem solved :)
I remove all data from uzytkownik table and it's go.

Answer 1

If you want one-to-one - you cannot have both the primary-key and the foreign-key specified. One-to-one is modeled via primary-keys (pk == pk), otherwise it becomes 'multiplicity' (and just typical one-to-many).
To get what you want just remove your other PK - and user UserId as both primary and fk...
[Table("Uzytkownik")]
public class Uzytkownik
{
// [Key] public int UzytkownikID { get; set; }
[Key]
public int UserId { get; set; }
[ForeignKey("UserId")]
public UserProfile UserProfile { get; set; }
}