Question

i can add a value to array(0), but when i then add a value to array(1) it clears the value for array(0). I’ve tried every way I can think of to declare and create the array. My code looks like this:

Dim aryEstimateInfo() As String = New String(7) {}

Private Sub wzrdEstimateWizard_NextButtonClick(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.WizardNavigationEventArgs) Handles wzrdEstimateWizard.NextButtonClick

    Select Case wzrdEstimateWizard.ActiveStepIndex
        Case 0 'first estimate wizard step
            aryEstimateInfo(0) = rad_lstVehicleType.SelectedItem.ToString

        Case 1 'second estimate wizard step
            Dim DamageZoneSelected As Boolean = False
            For Each cntrl As Control In pnlDamageZone.Controls
                If TypeOf cntrl Is RadioButton Then
                    Dim RadButton As RadioButton = cntrl
                    If RadButton.Checked Then
                        DamageZoneSelected = True
                        DamageZone = RadButton.Text.ToString
                        Exit For
                    Else
                        DamageZoneSelected = False
                    End If
                End If
            Next
            If DamageZoneSelected = True Then
                lblDamageZoneError.Visible = False
                aryEstimateInfo(1) = DamageZone
            Else
                'if no damage zone is selected a message is displayed
                wzrdEstimateWizard.ActiveStepIndex = 2
                wzrdEstimateWizard.ActiveStepIndex = 1
                lblDamageZoneError.Visible = True
            End If

        Case 2 'third estimate wizard step
            'assigns the number of dents to the estimate array
            aryEstimateInfo(2) = ddlNumberOfDents.SelectedValue.ToString
            'sets the average dent size  in the estimate arrau
            aryEstimateInfo(3) = ddlDentSize.SelectedValue.ToString
            'sets the add-on code and number of oversized dents
            If ddlOverSized.Enabled = True Then
                'aryEstimateInfo.SetValue("3", 4)
                aryEstimateInfo(4) = "3"
                aryEstimateInfo(7) = ddlOverSized.SelectedValue.ToString
            Else
            End If
        Case 3 'fourth estimate wizard step
        Case Else
    End Select

End Sub

I’m using this in an ASP.Net wizard control and in basic, visual studio 2010.

Answer 1

The problem is that each button click is posting back the page, which causes your aryEstimateInfo to be re-created on each postback.

In order to handle this situation elegantly, improve the maintenance of the page, and make it easier to debug this sort of situation in the future, I recommend the following changes:

1) Change the array to a class with properties:

Public Class EstimateInfo
  Public VehicleType As String = ""
  Public DamageZone As String = ""
  Public NumberOfDents As String = ""
  Public DentSize As String = ""
  Public AddOnCode As String = ""
  Public Oversized As String = ""
End Class

Note that all of the properties are declared as string, but the data types should probably be changed to more accurately reflect the underlying content.

This approach will help debugging because you can change the auto-implemented property to a getter/setter so that you can place a breakpoint to see where the value is getting cleared:

Private m_sVehicleType As String = ""
Public Property VehicleType As String
   Get
       Return m_sVehicleType
   End Get
   Set (Value As String
        ' You could set a breakpoint here to discover where the value is getting cleared.
       m_sVehicleType = Value
   End Set
End Property

And if you need to have the values in a string array for export to a different application or database, for example, you could add a method to the class to produce an appropriate string array.

2) Add a property to the page to store the current answer class in the page’s ViewState so that you won’t have to continuously re-populate the array. For example:

Private Property EstimateInfo As EstimateInfo
    Get
       ' Add a new record to the viewstate if it doesn't already exist
       If ViewState("EstimateInfo") Is Nothing Then
          Me.EstimateInfo = New EstimateInfo
       End If
       Return ViewState("EstimateInfo")
    End Get
    Set (value As EstimateInfo)
        ViewState("EstimateInfo") = value
    End Set
End Property

Once you do this, your wizard code becomes much easier to understand and maintain:

Select Case wzrdEstimateWizard.ActiveStepIndex
    Case 0 'first estimate wizard step
        Me.EstimateInfo.VehicleType = rad_lstVehicleType.SelectedItem.ToString