建立商品功能的模組

 public class ItemView
    {
        public List<int> IdList { get; set; }
        public List<ItemDetailView> ItemBlock { get; set; }
        public ForPaging Paging { get; set; }
    }
    
    [MetadataType(typeof(ItemMetadata))]
    public partial class Item
    {
        private class ItemMetadata
        {
            [DisplayName("商品編號")]
            public int Id { get; set; }

            [DisplayName("商品名稱")]
            public string Name { get; set; }

            [DisplayName("價格")]
            public int Price { get; set; }

            [DisplayName("圖片")]
            public string Image { get; set; }
        }
    }
    
    public Item GetDataById(int Id)
        {
            return db.Item.Find(Id);
        }
        public List<int> GetIdList(ForPaging Paging)
        {
            IQueryable<Item> Data = db.Item;
            Paging.MaxPage = Convert.ToInt32(Math.Ceiling(
                Convert.ToDouble(Data.Count()) / Paging.ItemNum));
            Paging.SetRightPage();
            return Data.OrderByDescending(p => p.Id)
                .Skip((Paging.NowPage - 1) * Paging.ItemNum).Take(Paging.ItemNum)
                .Select(p => p.Id).ToList();
        }
        public void Insert(Item newData)
        {
             db.Item.Add(newData);
            db.SaveChanges();
        }

        public void Delete(int Id)
        {
            Item DeleteData = db.Item.Find(Id);
            List<CartBuy> DeleteCartBuyList = DeleteData.CartBuy.ToList();
            foreach (CartBuy Delete in DeleteCartBuyList)
            {
                db.CartBuy.Remove(Delete);
            }
            db.SaveChanges();
            db.Item.Remove(DeleteData);
            db.SaveChanges();
        }