Stop radio button change

Question

I have radio button list that calls a function.

If the function returns true then I want to change the value.

However if the function returns false then I do not want to change the value and keep the original selection value.

Currently it changes the value even when the statement returns false.

Any advice?

ASP Page

<asp:RadioButtonList ID="rblType" runat="server" AutoPostBack="True" 
    DataSourceID="SqlData" DataTextField="Type" 
    DataValueField="TypeID">
</asp:RadioButtonList>

VB file

Private selectionvalue As Integer   

Protected Sub rblType_SelectedIndexChanged(sender As Object, e As System.EventArgs) Handles rblType.SelectedIndexChanged

    Dim CheckListValidation As Boolean = CheckListBox()

    If CheckListValidation = True Then
            selectionvalue = rblType.SelectedItem.Value
        Else
            rblType.SelectedItem.Value = selectionvalue
    End If

End Sub

Function CheckListBox() As Boolean

    If lstbox.Items.Count <> "0" Then
        If MsgBox("Are you sure you want to change option?", MsgBoxStyle.YesNo, " Change  Type") = MsgBoxResult.Yes Then
            Return True
        Else
            Return False
        End If
    Else
        Return True
    End If

End Function

Answer 1

The problem is when rblType_SelectedIndexChanged is executed, the selected item is already changed and the RadioButtonList doesn't "remember" the previously selected value. You need to keep the previously selected value between postbacks in order to achieve this.

I would suggest using ViewState. Create a property in code behind to represent the ViewState value:

Private Property PreviousSelectedValue() As String
    Get
        If (ViewState("PreviousSelectedValue") Is Nothing) Then
            Return String.Empty
        Else
            Return ViewState("PreviousSelectedValue").ToString()
        End If
    End Get
    Set(ByVal value As String)
        ViewState("PreviousSelectedValue") = value
    End Set
End Property

and in rblType_SelectedIndexChanged:

Protected Sub rblType_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles rblType.SelectedIndexChanged

    Dim CheckListValidation As Boolean = CheckListBox()

    If CheckListValidation = True Then
        'save the currently selected value to ViewState
        Me.PreviousSelectedValue = rblType.SelectedValue
    Else
        'get the previously selected value from ViewState 
        'and change the selected radio button back to the previously selected value
        If (Me.PreviousSelectedValue = String.Empty) Then
            rblType.ClearSelection()
        Else
            rblType.SelectedValue = Me.PreviousSelectedValue
        End If
    End If

End Sub