public void AddUserReview(string id_user, string owner, int mark, string text)
 {
     review r = new review
     {
         Id_Owner = owner,
         Id_User = id_user,
         Mark = mark,
         Text = text
     };
     context.reviews.Add(r);
     context.SaveChanges();
     UpdateUserRaiting(r.Id_User);
 }