[back to Anatomy of a Domino e-commerce Web site (Part 2)]

The AddtoCart agent
Here is the code for the AddtoCart agent:

Sub Initialize

Dim s As New NotesSession
Dim db As NotesDatabase
Dim doc As NotesDocument, oiDoc As NotesDocument, cDoc As NotesDocument
Set db = s.CurrentDatabase

Set doc = s.DocumentContext

Dim vCartID As Variant, vISBN As Variant, vItemID As Variant, vMedia As Variant, vQuantity As Variant, vPosn As Variant, vPath As Variant
Dim vOrderKey(1) As String

'Determine CartID
vCartID = Evaluate ({ @Middle (@LowerCase(Query_String) + "&"; "&cartid="; "&") }, doc)
If vCartID(0) = "" Then
vCartID= Evaluate({@Middle(@LowerCase(HTTP_COOKIE) + ";";"cartid=";";")}, doc)
End If
'Get ISBN from URL
vISBN = Evaluate ({ @Middle (@LowerCase(Query_String) + "&"; "&isbn="; "&") }, doc)

'Get the catalog document using the ISBN as the key
Set cDoc = db.GetView ("ISBNLookup").GetDocumentByKey (vISBN(0))

' Get the existing order item document, if it exists.
vOrderKey(0)=vCartID(0)
vOrderKey(1)=vISBN(0)
Set oiDoc = db.GetView ("OrderISBNLookup").GetDocumentByKey (vOrderKey)

' Create new order item document in the event one was not found
If oiDoc Is Nothing Then
Set oiDoc = db.CreateDocument
oiDoc.Form = "OrderItem"
oiDoc.CartID = vCartID
oiDoc.Quantity = 1
oiDoc.ISBN = vISBN
oiDoc.Title = cDoc.Title
oiDoc.Author = cDoc.Author

'Get position of media type from catalog and retrieve
cDoc.tempISBN = vISBN
vPosn = Evaluate ({@Member (tempISBN; MediaISBNs)}, cDoc) ' position of ISBN in catalog entry doc
cDoc.tempPosn = vPosn
vMedia = Evaluate ( {@If (tempPosn = 0; "Error"; @Subset (@Subset (MediaTypes; tempPosn); -1))}, cDoc)
oiDoc.Media = vMedia
Else
oiDoc.Quantity=oiDoc.Quantity(0) + 1
End If

'Even if this is an existing Order Item we can go ahead and update the information. Possibly prices have
'changed.
cDoc.tempISBN = vISBN
vPosn = Evaluate ({@Member (tempISBN; @lowercase (MediaISBNs))}, cDoc) ' position of ISBN in catalog entry doc
cDoc.tempPosn = vPosn
vPrice = Evaluate ( {@If (tempPosn = 0; "Error"; @Subset (@Subset (MediaPrices; tempPosn); -1))}, cDoc)
oiDoc.Price = vPrice

Call oiDoc.Save (True, True)

'Set URL path for return
vPath=Evaluate({@ReplaceSubstring (@Subset (@DbName; -1); "\\" : " "; "/" : "+")})
Print "[" + vPath(0) + "/cart?ReadForm&CartID=" + vCartID(0) + "]"

End Sub