Can't keep running totals - ASP.NET / VB

Question

I have an assignment to create a website that people can use to make dinner reservations. We are using Visual Basic code for the forms. It's supposed to keep running totals of each type of dinner. I'm having trouble getting the running totals to not reset to zero. I have them declared outside of the button click event. Not sure where I went wrong. Here's the code:

Option Strict On


Partial Class _Default
Inherits System.Web.UI.Page

Private Chicken_RT As Integer
Private Rib_RT As Integer
Private Veg_RT As Integer

Protected Sub SubmitButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles SubmitButton.Click
    'Variables
    Dim DinnerPrice As Integer
    Dim RadioSelect As Boolean = True
    Dim Tickets As Integer
    Dim DinnerType As String

    'Parsing
    Tickets = Integer.Parse(TicketTextBox.Text)

    'Validation / Calculations
    If TicketRangeValidator.IsValid And TicketValidator.IsValid Then
        If ChickenRadio.Checked = True Then
            DinnerPrice = Tickets * 15
            Chicken_RT += Tickets
            DinnerType = "Chicken"
        ElseIf RibRadio.Checked = True Then
            DinnerPrice = Tickets * 20
            Rib_RT += Tickets
            DinnerType = "Rib"
        ElseIf VegetarianRadio.Checked = True Then
            DinnerPrice = Tickets * 12
            Veg_RT += Tickets
            DinnerType = "Vegetarian"
        Else
            RadioErrorLabel.Text = ("Please select a dinner type")
            RadioSelect = False
        End If

        'Display results
        If RadioSelect = True Then
            If OpenBarCheckBox.Checked = True Then
                DinnerPrice += Tickets * 15
                OpenBarLabel.Text = "Yes"
            Else
                OpenBarLabel.Text = "No"
            End If

            NumberDinnersLabel.Text = Tickets.ToString()
            DinnerTypeLabel.Text = DinnerType
            TotalCostLabel.Text = DinnerPrice.ToString("C")
            TotalChickenLabel.Text = Chicken_RT.ToString()
            TotalRibLabel.Text = Rib_RT.ToString()
            TotalVegetarianLabel.Text = Veg_RT.ToString()

        End If
    End If

End Sub

End Class

score 3 · Answer 1 · answered Apr 10 '12 at 21:18

I have [the running totals] declared outside of the button click event.

Every time you handle an event, you're working with a new instance of your page class.

Understand that, and everything that's happening here should start to make sense to you. You must keep your totals in a place that persists across individual http requests, such as viewstate, the session, the application cache, on the file system, or in a database. Variables in your class to do not persist across individual http requests.

score 2 · Accepted Answer · answered Apr 10 '12 at 21:42

As Joel said, the values will not persist as each HTTP request creates a new instance of your class. The HiddenField Class would suit you nicely in this situation.

First, remove these lines of code:

    Private Chicken_RT As Integer
    Private Rib_RT As Integer
    Private Veg_RT As Integer

Second, put this in your .aspx Markup (nested in the Form tag):

    <asp:HiddenField id="Chicken_RT" runat="server" value="0"/>
    <asp:HiddenField id="Rib_RT" runat="server" value="0"/>
    <asp:HiddenField id="Veg_RT" runat="server" value="0"/>

Finally,

Veg_RT += Tickets

Becomes:

Veg_RT.Value = (CInt(Veg_RT.Value) + Tickets).ToString()

(Repeat for all of your running totals.)

To access your totals you would do:

Dim intVegTotal As Integer = CInt(Veg_RT.Value)

Thanks, that helped a lot. I picked this class up after dropping my economics class so I missed the first three classes. — Shane, Apr 11 '12 at 02:41

score 1 · Answer 3 · answered Apr 10 '12 at 18:05

1

Well, I see you are reading TicketTextBox, but I don't see you assigning it any where. If you don't assign it, won't it's value always be zero?

answered Apr 10 '12 at 18:05

Sam

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I'm assigning it to the variable `Tickets`. – Shane Apr 10 '12 at 18:21
Correct, but you never assign your value of Tickets back to the TicketTextBox. So every time you click the button, Tickets is being calculated from 0. – Sam Apr 10 '12 at 19:49

Can't keep running totals - ASP.NET / VB

3 Answers3