samplecode.aspx

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<%@Page Language="VB"%>
<%@ Import Namespace="System.IO" %>

<script runat=server>

	Dim shoppingCart As Hashtable

	Protected Sub Page_Load(sender As Object, e As EventArgs)

'		If ViewState("cart") Is Nothing Then
'			shoppingCart = New Hashtable()
'			ViewState("cart") = shoppingCart
'		Else
'			shoppingCart = ViewState("cart")
'		End If

		If IsPostBack = True Then
			shoppingCart = Session("cart")
		Else
			shoppingCart = New Hashtable()
			Session("cart") = shoppingCart
		End If

	End Sub
	

	' Add an item to the cart 
	Protected Sub OnAddItemToCart(sender As Object, e As EventArgs)

		If shoppingCart.ContainsKey( ProductCode.Text ) = True Then
			status.InnerHtml = "Product code already in cart"
		Else
			shoppingCart.Add( ProductCode.Text, ProductDescription.Text )
		End If
		
	End Sub
	
	
	' Read an item from the cart 
	Protected Sub OnReadItemFromCart(sender As Object, e As EventArgs)
	
		If shoppingCart.ContainsKey( ProductCode.Text ) = False Then
			status.InnerHtml = "Product code not in cart"
			Return
		End If

		If Not (shoppingCart(ProductCode.Text) Is Nothing)
			ProductDescription.Text = shoppingCart(ProductCode.Text).ToString()
		End If
		
	End Sub
	
	
	' Delete an item from the cart
	Protected Sub OnDeleteItemFromCart(sender As Object, e As EventArgs)
	
		If shoppingCart.ContainsKey( ProductCode.Text ) = False Then
			status.InnerHtml = "Product code not in cart"
			Return
		End If

		shoppingCart.Remove( ProductCode.Text )
		
	End Sub
	

	' Updated an item in the cart
	Protected Sub OnUpdateItemInCart(sender As Object, e As EventArgs)
	
		If shoppingCart.ContainsKey( ProductCode.Text ) = False Then
			status.InnerHtml = "Product code not in cart"
			Return
		End If

		shoppingCart(ProductCode.Text) = ProductDescription.Text
	
	End Sub


</script>

<form runat=server>

<h3>Items in Cart</h3>

<%

	If shoppingCart.Count <> 0 Then

		Response.Write("<table>")
		Response.Write("<tr bgcolor=cornflowerblue>")
		Response.Write("<td>Product Code")
		Response.Write("<td>Product Description")
		Response.Write("</tr>")

		Dim key As String
		for each key In shoppingCart.Keys
			Response.Write("<tr>")
			Response.Write("<td>" & key )
			Response.Write("<td>" & (string) shoppingCart(key) )
		Next
		Response.Write("</table>")
	Else
		Response.Write("<P>There are no items in the cart at the moment")
	End If
%>

<hr />
<h3>Add/Delete/Update Item</h3>

<table>
<tr>
	<td>Code:</td>
	<td><asp:TextBox id=ProductCode runat=server EnableViewState=False />
<tr>
	<td>Description:</td>
	<td><asp:TextBox id=ProductDescription runat=server EnableViewState=False />

<tr>
	<td colspan=2>
		<asp:Button OnClick="OnAddItemToCart" Text="Add Item" runat=server />
		<asp:Button OnClick="OnReadItemFromCart" Text="Read Item" runat=server />
		<asp:Button OnClick="OnDeleteItemFromCart" Text="Delete Item" runat=server />
		<asp:Button OnClick="OnUpdateItemInCart" Text="Update Item" runat=server />
</table>

</form>

<p style="color:red" id=status EnableViewState=False runat=server />