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Subject:
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Problems with Sessions
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Posted By:
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HelpWanted
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Post Date:
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12/6/2006 7:19:06 AM
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Hi
I am having problems with Sessions, for which is now starting to drive me slightly barmy, this is to keep the session when moving from page to page so that when returning to a cart the items are still in place that have been added.
Please see the code below in which I am trying to resolve: -
Dim objDT As System.Data.DataTable
Dim objDR As System.Data.DataRow
Sub Page_Load(s As Object, e As EventArgs)
objDT = New System.Data.DataTable("Cart")
objDT = Session("Cart")
Session("Cart") = objDT
If Not IsPostBack Then
makeCart()
End If
End Sub
Function makeCart()
objDT = New System.Data.DataTable("Cart")
objDT.Columns.Add("ID", GetType(Integer))
objDT.Columns("ID").AutoIncrement = True
objDT.Columns("ID").AutoIncrementSeed = 1
objDT.Columns.Add("Quantity", GetType(Integer))
objDT.Columns.Add("Product", GetType(String))
objDT.Columns.Add("Cost", GetType(Decimal))
Session("Cart") = objDT
End Function
Sub AddToCart(s As Object, e As EventArgs)
objDT = Session("Cart")
Dim Product = ddlProducts.SelectedItem.Text
Dim blnMatch As Boolean = False
For Each objDR In objDT.Rows
If objDR("Product") = Product Then
objDR("Quantity") += txtQuantity.Text
blnMatch = True
Exit For
End If
Next
If Not blnMatch Then
objDR = objDT.NewRow
objDR("Quantity") = txtQuantity.Text
objDR("Product") = ddlProducts.SelectedItem.Text
objDR("Cost") = Decimal.Parse(ddlProducts.SelectedItem.Value)
objDT.Rows.Add(objDR)
End If
Session("Cart") = objDT
dg.DataSource = objDT
dg.DataBind()
lblTotal.Text = "£" & GetItemTotal()
End Sub
Function GetItemTotal() As Decimal
Dim intCounter As Integer
Dim decRunningTotal As Decimal
For intCounter = 0 To objDT.Rows.Count - 1
objDR = objDT.Rows(intCounter)
decRunningTotal += (objDR("Cost") * objDR("Quantity"))
Next
Return decRunningTotal
End Function
Sub Delete_Item(s As Object, e As DataGridCommandEventArgs)
objDT = Session("Cart")
objDT.Rows(e.Item.ItemIndex).Delete()
Session("Cart") = objDT
dg.DataSource = objDT
dg.DataBind()
lblTotal.Text = "£" & GetItemTotal()
End Sub
Any help with this would be greatly appreciated.
Thanks
Sharon
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Reply By:
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HelpWanted
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Reply Date:
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12/7/2006 3:48:29 PM
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I seem to have resolved part of the problem with this now, which seems to be from the Page_Load section of the code: -
Private Sub Page_Load(ByVal Sender As System.Object, ByVal E As System.EventArgs)
If Not IsPostBack Then
objDT = New DataTable()
makeCart()
Session("Cart") = objDT
dg.DataSource = (CType(Session("Cart"), DataTable))
dg.DataBind()
End If
End Sub
It seems to have resolved the issue of part of the table disappearing but the data is still not staying in the session so still plodding on with this, again any suggestions would be grateful.
Thanks
Sharon
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Reply By:
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dparsons
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Reply Date:
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12/7/2006 3:56:43 PM
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IMHO, this is a poor way to manage a shopping cart simply because you pass the entire cart around in session. This can become problematic (outside of the problme you are having) and cause your server preformance to grind because you are storing all of that information in session. (Consider 10000 users at your site all at once with shopping carts that each contain 30 unique items consider still, if the user doesnt log out and just leaves the page, the application will hold onto that session in memory until the session timesout.)
You are already storing the information in a database, I would suggest that you keep the cart there and just pass a cartID around in session that relates back to a row in your database, this is much more effecicent.
In so far as why your session is being lost, I can't see anything that stands out, I might suggest stepping through your code to see what the compiler is doing.
hth.
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I will only tell you how to do it, not do it for you.
Unless, of course, you want to hire me to do work for you.
^^Thats my signature
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