Charon Cart Version 2 Tutorial

This is a comprehensive tutorial outlining the steps neccessary to implement a shopping cart on a site using the excellent Charon Cart Extension. It is suitable for all but the very novice Ultradev user. The only requisite skills are an ability to create filtered recordsets and some familiarity with the Goto Link Page behaviour.

There are well illustrated steps to all the Charon Cart features, a short discussion on database design and a commented version of the server side code included with this extension.

This tutorial has been written with the kind permission of the extension author Jules Roberts. Corrections and suggestions are welcomed.

Checkout and Order Submission

The checkout is where the final basket is displayed complete with any VAT/sales tax, shipping amounts and applied discounts. Here you are asking the user to confirm that this is indeed the order they wish to make. This is a complex page that like the Add Item From Form page uses a form that submits back to itself with all the necessary details to do all or some of the following; store the order and get an order ID, store the order to a database table, submit the order to an online payment agency, clear the cart, redirect the user, calculate shipping and tax costs from either a static amount or from a database and calculating the final grand total! If the order is to the users satisfaction then it can be submitted and saved to a database whilst updating stock control figures if required.

It is still not difficult to set up however if care is taken.

Setting up the Cart Display

The first step is to design a table to display the cart contents. This is done in a similar way as in the previous section but the table does not include the UPDATE functionality. Although it is possible to include both the UPDATE and the SUBMIT order functions it is far simpler to assume that the user is happy with the order when they click on the checkout link. If not they can always go back and use the view cart page to alter the order. A typical table is shown below.

Here the repeat region would encapsulate the row containing the CC.Quantity, CC.Name, CC.Price and CC.[LineTotal] items. These and the other cart objects; SubTotal, Discount, Shipping, SalesTax and GrandTotal are simply dragged from the Charon Cart recordset in the same way as for any other recordset. Items such as shipping, discount and tax need to be calculated and the code added to the page to do so as described below.

next adding shipping costs....
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Comments

A VERY important tip for use with Dreamweaver MX

November 15, 2002 by Ivan Halen

I found that storing the Order and the Cart to a Database with Dreamweaver MX requires a slight modify to both the rsOrders and rsOrderDetails Recordsets (pages 13/14 of the tutorial).

In order to work properly, you have to change the LockType from Read Only (this is the default LockType in DreamweaverMX) to Optimistic. To do so, just select your Recordsets in the Server Behaviors Panel one at a time, then go to the Properties bar and change the Lock Type as I said above.

Maybe on Ultradev the default Lock Type is Optimistic (remember that's NOT so on Dreamweaver MX), so Rolf didn't mentioned in his tutorial. If you don't change the Lock Type, you'll get this error:

"ADODB.Recordset (0x800A0CB3)
Current Recordset does not support updating. This may be a limitation of
the provider, or of the selected locktype."

(as you see you find the word "locktype" in the error, and it's quite easy to understand: not so if you are using a non-english version of IIS or PWS, as me)

Oh, Rolf! Please change the Image029.gif on page 14: the selected Recordset is rsOrders and not rsOrderDetails, and that maybe confusing for the new user.

Happy Carting! :-)

About the Tutorial

November 17, 2002 by Kamran Aslam

I think the tutorial is tooo long. it will be better if it will be a little shorter or in other means " to the point" But anyways its good. but boaring too beacuse of too much text i guess.

Thanks anyways for the good things.

Pretty Good Until SSL

January 1, 2003 by James Threadgill

This was a pretty good tutorial until you left me hanging out to dry without a way to pass my cart over to my SSL connection. I found a form variable or a querystring works fine for this. In order to implement such a scheme one must create a modified version of the inc_CharonCart.asp, so that the function CookieToCart reads the values in from the form variable or querystring after one establishes the SSL connection. I modified it like so and saved it as ssl_inc_CharonCart.asp:

<%
CONST CC_ProductID = 0
CONST CC_Quantity = 1
CONST CC_Name = 2
CONST CC_Price = 3
CONST CC_UniqueKey = 4

CCcart=CookieToCart("SoftwareCart")
CCcart_SubTotal=0
CCcart_numItems=0
CCcart_Shipping=0
CCcart_Discount=0
CCcart_SalesTax=0
isFound=false

for i="0" to ubound(CCcart,2)
if CCcart(CC_ProductID,i) <> "" then
isFound=true
CCcart_SubTotal=CCcart_SubTotal + (CCcart(CC_Quantity,i)*CCcart(CC_Price,i))
CCcart_numItems=CCcart_numItems + 1
end if
next

function CCcart_LineTotal
CCcart_LineTotal=CCcart(CC_Quantity,i)*CCcart(CC_Price,i)
end function

function CCcart_GrandTotal
CCcart_GrandTotal=CCcart_SubTotal + CCcart_Shipping + CCcart_SalesTax - CCcart_Discount
end function

function CookieToCart(cookiename)
mystring=Request("Cart")
dim myarray(5,50)
productarray=split(mystring,"|")
for j="0" to ubound(productarray)
itemarray=split(productarray(j),"^")
for i="0" to 5
if itemarray(i) <> "" then
myarray(i,j)=itemarray(i)
else
myarray(i,j)=null
end if
next
next
CookieToCart=myarray
end function
%>

Notice the variable "mystring" in function CookieToCart now gets the cookie using a generic request. The other difference is--unless you are allowing Cart Updates on your checkout page--is the the CartToCookie function and the code to initialize the cart array are no longer needed and can be removed for clarity as I have.