public bool insert(Order entity, DetailOrder[] items)
 {
     try
     {
         entity.CreatedAt = DateTime.Now;
         entity.Status = false;
         db.Orders.Add(entity);
         db.SaveChanges();
         ProductService serv = new ProductService();
         Product temp = null;
         foreach (DetailOrder item in items)
         {
             item.OrderId = entity.id;
             temp = serv.findById(item.ProductId);
             temp.Quantity = temp.Quantity.Value - item.Quantity.Value;
             serv.update(temp);
         }
         db.DetailOrders.AddRange(items);
         db.SaveChanges();
         return true;
     }
     catch
     {
         return false;
     }
 }
 public bool delete(long id)
 {
     try
     {
         Order o = db.Orders.Find(id);
         DetailOrder[] items = db.DetailOrders.Where(d => d.OrderId == id).ToArray();
         ProductService serv = new ProductService();
         foreach (DetailOrder item in items)
         {
             Product p = serv.findById(item.ProductId);
             p.Quantity = p.Quantity + item.Quantity;
             serv.update(p);
         }
         db.DetailOrders.RemoveRange(items);
         db.Orders.Remove(o);
         db.SaveChanges();
         return true;
     }
     catch
     {
         return false;
     }
 }