public async Task<Order> UpdateOrderAsync(Order order)
 {
     if (!_context.Orders.Local.Any(o => o.Id == order.Id))
     {
         _context.Orders.Attach(order);
     }
     _context.Entry(order).State = EntityState.Modified;
     await _context.SaveChangesAsync();
     return order;
 }
 public async Task<Order> AddOrderAsync(Order order)
 {
     _context.Orders.Add(order);
     await _context.SaveChangesAsync();
     return order;
 }