Question

I’ve been experimenting with this and trying to understand the Page Life Cycle for hours upon hours. I’m completely stumped at this point :'( Any help would be GREATLY appreciated.

Below are my methods. My _PrefillWizard method actually works for all the controls on my page except for those which are dynamically populated. The CheckBoxLists are such because they are automatically generated based on selectable values in a table in my DB. I already have this control in my markup like so… how do I force this to load and be ready before running my other code?

<asp:CheckBoxList ID="MyLanguagesCBL" runat="server" RepeatDirection="Vertical"
    RepeatColumns="4" Width="100%" DataSourceID="LanguagesSDS"
    DataTextField="Language" DataValueField="ID">
</asp:CheckBoxList>
<asp:SqlDataSource ID="LanguagesSDS" runat="server" 
    ConnectionString="<%$ ConnectionStrings:ConnectionString1 %>"
    SelectCommand="select ID, [Language] from LanguagesListTable"
    DataSourceMode="DataReader">
</asp:SqlDataSource>

Obviously these particular controls are not yet generated or on the page by the time my _PrefillWizard has been called, resulting in none of the CheckBoxes being pre-filled. How do I make them generate before my prefill method is called? Thanks 😉

The click event that kicks things off.

'On "Load" Button click, clears a Wizard control and Prefills it with the
'  data from the clicked record based on the primary key stored in SessionState.
Protected Sub RowClick(ByVal sender As Object, ByVal e As GridViewCommandEventArgs) Handles GridView2.RowCommand
    If e.CommandName = "Select" Then
        Session.Add("ClickedPrimaryKey", GridView2.DataKeys(e.CommandArgument).Value.ToString)
        'This is the main function which calls "_SetCheckBoxes" among others.
        _PrefillWizard(Session.Item("ClickedPrimaryKey"))
    End If
End Sub

Here’s my function for populating the my CheckBoxList control, but it obviously depends on the control having already been loaded on the page.

'Parse a CSV String from the Database back into CheckBoxList Selections
Protected Sub _SetCheckBoxes(ByRef cbl As CheckBoxList, ByRef dt As DataTable, ByVal row As Integer, ByVal csv As String)
    'Do something if there is a value in the cell
    If Not IsDBNull(dt.Rows.Find(row)(csv)) Then
        For Each item As ListItem In cbl.Items
            item.Selected = False 'Reset the checkbox first
            'Then, if the ID value of the checkbox corresponds to a value 
            '  in the CSV string, then tick the checkbox.
            If csv.Contains(item.Value) Then
                item.Selected = True
            End If
        Next
    End If
End Sub

Answer 1

You guys will probably get a kick out of this, but the answer was so obvious that I didn’t even catch it all this time. Of course I was preoccupied with about 10 other functions too >.<

Here’s the answer. You’ll notice that in my _SetCheckBoxes method, I first checked to ensure that a value existed for the particular csv string, but also notice, that I failed to actually SET it to the corresponding value string afterward. This isn’t immediately apparent, but what I was actually passing in as csv was the name of the Column in my DataTable where the string actually lived.

csv = dt.Rows.Find(row)(csv).ToString

That line added immediately after my IsDBNull check, fixed my problem. 🙂