Shopping cart & Data Access

Question

User-394943341 posted

Hi, 

I'm in the process of learning asp.net web forms & C# so please bear with me!

I've cannibalized a bit of C# code off the internet (https://code.tutsplus.com/tutorials/build-a-shopping-cart-in-aspnet--net-1663) and I'm struggling to populate & refer to a couple of properties from my data class.

My CartProducts class (not sure where the constructor should include the Desc & Price fields....also tried setting _desc as a fixed value to test things...):

   public class CartProducts
    {
        private int _prodID; public int ProdID
        {
            get { return _prodID; }
            set { _prodID = value; }
        }

        private string _desc; public string Desc
        {
            get { return _desc; }
            set { _desc = value; }
            //set { _desc = "abcde12"; } //tried hard coding values.....
        }

        private decimal _price; public decimal Price
        {
            get { return _price; }
            set { _price = value; }
        }

        //constructor for products on customer order form
        //public CartProducts(int Prod_ID, string cust_acc_prod, decimal smdea_rate1)
        //{
        //    _prodID = ProdID; _desc = Desc; _price = Price;
        //}
        //constructor for products on customer order form
        public CartProducts(int _prodID)
        {
            _prodID = ProdID;
        }
    }

This is the cannibilized code:

 public class ShoppingCart
    {
        #region Properties

        public List<CartItem> Items { get; private set; }

        #endregion

        #region  Implementation

        // The static constructor is called as soon as the class is loaded into memory 
        public static ShoppingCart GetShoppingCart()
        {
            // If the cart is not in the session, create one and put it there
            if (HttpContext.Current.Session["ASPNETShoppingCart"] == null)
            {
                ShoppingCart cart = new ShoppingCart();
                cart.Items = new List<CartItem>();
                HttpContext.Current.Session["ASPNETShoppingCart"] = cart;
            }

            return (ShoppingCart)HttpContext.Current.Session["ASPNETShoppingCart"];
        }

        // A protected constructor ensures that an object can't be created from outside
        protected ShoppingCart() { }

        #endregion

        #region Item Modification Methods
        /**
         * AddItem() - Adds an item to the shopping 
         */
        public void AddItem(int productId) //add desc & price??
        {
            // Create a new item to add to the cart
            CartItem newItem = new CartItem(productId);

            // If this item already exists in our list of items, increase the quantity
            // Otherwise, add the new item to the list
            if (Items.Contains(newItem))
            {
                foreach (CartItem item in Items)
                {
                    if (item.Equals(newItem))
                    {
                        item.Quantity++;
                        return;
                    }
                }
            }
            else
            {
                newItem.Quantity = 1;
                Items.Add(newItem);
            }
        }

        /**
         * SetItemQuantity() - Changes the quantity of an item in the cart
         */
        public void SetItemQuantity(int productId, int quantity)
        {
            // If we are setting the quantity to 0, remove the item entirely
            if (quantity == 0)
            {
                RemoveItem(productId);
                return;
            }

            // Find the item and update the quantity
            CartItem updatedItem = new CartItem(productId);

            foreach (CartItem item in Items)
            {
                if (item.Equals(updatedItem))
                {
                    item.Quantity = quantity;
                    return;
                }
            }
        }

        /**
         * RemoveItem() - Removes an item from the shopping cart
         */
        public void RemoveItem(int productId)
        {
            CartItem removedItem = new CartItem(productId);
            Items.Remove(removedItem);
        }
        #endregion

        #region Reporting Methods
        /**
         * GetSubTotal() - returns the total price of all of the items
         *                 before tax, shipping, etc.
         */
        public decimal GetSubTotal()
        {
            decimal subTotal = 0;
            foreach (CartItem item in Items)
                subTotal += item.TotalPrice;

            return subTotal;
        }
        #endregion
    }

    /**
 * The CartItem Class
 * 
 * Basically a structure for holding item data
 */
    public class CartItem : IEquatable<CartItem>
    {
        #region Properties

        // A place to store the quantity in the cart
        // This property has an implicit getter and setter.
        public int Quantity { get; set; }


        private int _productId; public int ProductId
        {
            get { return _productId; }
            set
            {
                // To ensure that the Prod object will be re-created
                _product = null;
                _productId = value;
            }
        }


 
        //https://code.tutsplus.com/tutorials/build-a-shopping-cart-in-aspnet--net-1663


            private CartProducts _product = null;
            public CartProducts Prod
            {
            get
            {
                // Lazy initialization - the object won't be created until it is needed
                if (_product == null)
                {
                    _product = new CartProducts(ProductId);
                }
                return _product;
            }
        }

        public int prodid
        {
            get { return ProductId; }
        }

        string dd = "dfdvjh"; //this works passing a fixed value
     
        
        public string Description
        {
            //get { return Prod._smdea_desc; }
            get { return dd; }
        }

        public string desc
        {
            //get { return Prod._smdea_desc; }
            get { return Prod.Desc; }
        }

        public decimal UnitPrice
        {
            get { return Prod.Price; }
        }

        public decimal TotalPrice
        {
            get { return UnitPrice * Quantity; }
        }

        #endregion

        // CartItem constructor just needs a productId
        public CartItem(int productId)
        {
            this.ProductId = productId;
        }

        /**
         * Equals() - Needed to implement the IEquatable interface
         *    Tests whether or not this item is equal to the parameter
         *    This method is called by the Contains() method in the List class
         *    We used this Contains() method in the ShoppingCart AddItem() method
         */
        public bool Equals(CartItem item)
        {
            return item.ProductId == this.ProductId;
        }
    }

I've altered the CartItem class to refer to my CartProducts class and this is where I'm stuck. As you can see I've set a string dd to test the Description value but I'm not sure how I go about obtaining the true CartProducts Desc & Price properties (and where I set them...I'm assumming in my code behind; do I need to alter cart.AddItem method to included Desc & Price??? )

Code behind (the web page displays a list of products with an AddToOrder button for each row):

  protected void gvProductsOrder_RowCommand(object sender, GridViewCommandEventArgs e)
        {
            // If multiple buttons are used in a GridView control, use the
            // CommandName property to determine which button was clicked.
            if (e.CommandName == "AddToOrder")
            {
                // Convert the row index stored in the CommandArgument
                // property to an Integer.
                int index = Convert.ToInt32(e.CommandArgument);

                // Retrieve the row that contains the button clicked 
                // by the user from the Rows collection.
                GridViewRow row = gvProductsOrder.Rows[index];

                //gets product id
                Label lblid = (Label)gvProductsOrder.Rows[index].FindControl("lbl_Prod_ID");
                int prodid = Convert.ToInt32(lblid.Text);

                //gets _cust_acc_prod
                Label lblcustaccprod = (Label)gvProductsOrder.Rows[index].FindControl("lbl_cust_acc_prod");
                string custaccprod = lblcustaccprod.Text;

                // Create a new ListItem object for the contact in the row.     
                ListItem item = new ListItem();
                item.Text = prodid.ToString() + " ~ " + custaccprod + " ~ " + Server.HtmlDecode(row.Cells[2].Text) + " ~ " +
                  Server.HtmlDecode(row.Cells[3].Text);

                // If the contact is not already in the ListBox, add the ListItem 
                // object to the Items collection of the ListBox control. 
                if (!OrderListBox.Items.Contains(item))
                {
                    OrderListBox.Items.Add(item);
                }

                //Response.Redirect("ViewCart.aspx");
                //add in here the price and description???
                ShoppingCart cart = ShoppingCart.GetShoppingCart();
                cart.AddItem(prodid);

My markup for the shopping cart (this only currently pulls in the prodid & hard-coded Description:

   <asp:GridView runat="server" ID="gvShoppingCart" AutoGenerateColumns="false" EmptyDataText="There is nothing in your shopping cart." GridLines="None" Width="100%" CellPadding="5" ShowFooter="true" 
                 DataKeyNames="ProductId" OnRowDataBound="gvShoppingCart_RowDataBound" OnRowCommand="gvShoppingCart_RowCommand">
              <%--  <HeaderStyle HorizontalAlign="Left" BackColor="#3D7169" ForeColor="#FFFFFF" />
                <FooterStyle HorizontalAlign="Right" BackColor="#6C6B66" ForeColor="#FFFFFF" />
                <AlternatingRowStyle BackColor="#F8F8F8" />--%>
                <Columns>
                <asp:BoundField DataField="prodid" HeaderText="prodid" />
       
                    <asp:BoundField DataField="Description" HeaderText="Description" />
                    <asp:TemplateField HeaderText="Quantity">
                        <ItemTemplate>
                            <asp:TextBox runat="server" ID="txtQuantity" Columns="5" Text='<%# Eval("Quantity") %>'></asp:TextBox><br />
                            <asp:LinkButton runat="server" ID="btnRemove" Text="Remove" CommandName="Remove" CommandArgument='<%# Eval("ProductId") %>' style="font-size:12px;"></asp:LinkButton>
 
                        </ItemTemplate>
                    </asp:TemplateField>
                    <asp:BoundField DataField="UnitPrice" HeaderText="Price" ItemStyle-HorizontalAlign="Right" HeaderStyle-HorizontalAlign="Right" DataFormatString="{0:C}" />
                    <asp:BoundField DataField="TotalPrice" HeaderText="Total" ItemStyle-HorizontalAlign="Right" HeaderStyle-HorizontalAlign="Right" DataFormatString="{0:C}" />
                </Columns>
            </asp:GridView>

Thanks in advance for any pointers in the right direction.