public void AddDishReview(string owner, int dish_id, int mark, string text)
{
dishreview dr = new dishreview
{
Id_Owner = owner,
Id_Dish = dish_id,
Mark = (int)mark,
Description = text
};
context.dishreviews.Add(dr);
context.SaveChanges();
double average = (double)context.dishreviews.Where(r=>r.Id_Dish == dish_id).Average(r => r.Mark);
dish d = GetDishById(dish_id);
d.Raiting = Convert.ToInt32(Math.Round(average, 0));
context.SaveChanges();
}