Shopping Cart in Asp.Net

Today i needed to add Shopping Cart functionality to one of my websites.
The solution i adopted is really simple, i did it in few minutes but i think it could be useful. It can be improved but it’s a good starting point if u just need a simple shopping cart.

I choosed this way:

• Create a class named ShoppingCart
• Create a class named CartItem to store item infos
• In the Session_Start event of Global.asax i create the ShoppingCart instance and add it to session. I named it Session(”ShoppingCart”)
• In each page that needs to access the Shopping Cart i use the stored Session(”ShoppingCart”) and use it’s methods

The Shopping Cart Class methods i wrote are:

• New, to create the empty cart
• Add, to add a CartItem object
• Modify, to vary the count of an item or remove it setting it’s count to zero
• Empty, to empty the Shopping Cart
• ItemTotal, to get the total price for an object (count * price)
• Total, to get the Shopping Cart total price to pay

The CartItem class contains these infos:

• ID
• Name
• Price
• Count

Here is the Code:

Public Class CartItem
    Public ID As String
    Public Name As String
    Public Price As Double
    Public Count As Integer
 
    Public Sub New()
        ID = "-1"
        Name = ""
        Price = 0
        Count = 0
    End Sub
End Class
 
Public Class ShoppingCart
    Public Items As New Hashtable
 
    Public Sub New()
        Items.Clear()
    End Sub
 
    'Add an item to the Shopping Cart
    Public Function Add(ByVal c As CartItem) As Boolean
        Dim tmpItem As CartItem
 
        If c.Name <> "" And c.Count > 0 Then
            tmpItem = Items(c.Name)
            If Not tmpItem Is Nothing Then
                tmpItem.Count += c.Count
            Else
                Items.Add(c.Name, c)
            End If
            Return True
        Else
            Return False
        End If
    End Function
 
    'Modify an object quantity
    'If quantity is zero the item is removed
    Public Function Modify(ByVal c As CartItem) As Boolean
        Dim tmpItem As CartItem
        If c.Name <> "" Then
            tmpItem = Items(c.Name)
            If Not tmpItem Is Nothing Then
                If tmpItem.Count > 0 Then
                    tmpItem.Count = c.Count
                Else
                    Items.Remove(c.Name)
                End If
                Return True
            Else
                Return False
            End If
        Else
            Return False
        End If
    End Function
 
    'Empty the Shopping Cart
    Public Sub Empty()
        Items.Clear()
    End Sub
 
    'calculate an object total price (items*price)
    Public Function ItemTotal(ByVal itemName As String) As Double
        Dim tmpItem As CartItem
        If itemName <> "" Then
            tmpItem = Items(itemName)
            If Not tmpItem Is Nothing Then
                Return tmpItem.Count * tmpItem.Price
            Else
                Return 0.0
            End If
        Else
            Return 0.0
        End If
    End Function
 
    'Calculate the total price to pay
    Public Function Total() As Double
        Dim totale As Double = 0.0
        For Each k As String In Items.Keys
            Dim ci As CartItem = Items(k)
            totale += ci.Price * ci.Count
        Next
        Return totale
    End Function
End Class

Download this code: ShoppingCart.vb.txt

In the Global.asax file you need to write

Sub Session_Start(ByVal sender As Object, ByVal e As EventArgs)
Session(”ShoppingCart”) = New ShoppingCart
End Sub

To Add an item to the Shopping Cart

Dim cart As ShoppingCart = Session(”ShoppingCart”)
Dim it As New CartItem
it.Name = “Test Object”
it.ID = “1″
it.Price = 100.22
it.Count = 1
cart.Add(it)

To Show the cart items

Dim cart As ShoppingCart = Session(”ShoppingCart”)
For Each k As String In cart.Items.Keys
Dim ci As CartItem = cart.Items(k)
Response.write(ci.Name + “-” + ci.Count.ToString() + ” Price: ” + ci.Price.ToString + ”
“)
Next
Response.Write(”Total: ” + cart.Total.ToString())