VB.net: Accessing data from DataList in Page_Load - vb.net

Question

New to VB.net, and trying to re-factor an 'old-skool' ASP page where all the page logic is happening on the .aspx page itself, to code-behind. Basically, I have a button that has a state, either on or off. If on, I set a hidden field to 1, if off, I set it to 0 (the default when a user visits the page).
The goal is to simply change the message I am sending to the user.
Have the following relevant code in MyPage.aspx:
<asp:HiddenField ID="hfldState" runat="server" Visible="false" Value="0" />
<div id="mainContent">
<asp:Literal ID="lblMessage" runat="server"
Visible="false" />
<asp:DataList ID="dlList" runat="server"
DataSourceID="sdsList"
DataKeyField="Entry No_"
RepeatLayout="Flow">
<ItemTemplate>
<div>
<asp:HyperLink ID="hlCurriculum" runat="server"
Text='<%# DataBinder.Eval(Container.DataItem, "Title") %>'
NavigateUrl='<%# DataBinder.Eval(Container.DataItem, "File Path") %>'
ToolTip='<%# DataBinder.Eval(Container.DataItem, "Title") %>'
Target="_blank"
Style="font-weight: bold;">
</asp:HyperLink>
</div>
</ItemTemplate>
</asp:DataList>
</div>
<asp:SqlDataSource ID="sdsList" runat="server"
ConnectionString="..."
SelectCommand="SELECT [Entry No_], [Title], [File Path] FROM [Table] WHERE ([State] = #State)">
<SelectParameters>
<asp:ControlParameter ControlID="hfldState" Name="State" Type="Int32" />
</SelectParameters>
</asp:SqlDataSource>
And the following in the Page_Load Sub:
If Page.IsPostBack Then
' Check for results
dlList.DataBind()
If dlList.Items.Count > 0 Then
' Results, display them
lblMessage.Text = "<h3>Results</h3>"
lblMessage.Visible = True
Else
' No results
lblMessage.Text = "<p>No Results</p>"
lblMessage.Visible = True
End If
Else
' user has not clicked anything
lblMessage.Text = "<p>Click button!</p>"
End If
The above code produces the following effect: when I click the button, setting the state to 1 and the page reloads, in Page_Load, I am getting zero results from the If dlList.Items.Count > 0 Then check, and thus am showing the 'No results' message, but the actual asp:DataList on the MyPage.aspx page is returning results... and then if I click the button again, setting it back to 0, in Page_Load, the datalist is now returning results, so I set the text to 'Results', but again, the control on the MyPage.aspx page behaves correctly, and shows no results, as expected. Now keep in mind that the above works perfectly in terms of checking the number of results if I move the If dlList.Items.Count > 0 Then page logic out of Page_Load and back to the MyPage.aspx file, it all works fine (i.e. results when state = 1, none when state = 0)
Any ideas?

Answer 1

I dont see a check in your page load for a postback:
If Not IsPostBack
'code
dList.DataBind() 'here is where you want to bind the data...
end if

Answer 2

The issue related to my ignorance of the page lifecycle in VB.net. Solution was to adjust the visibility of the asp:Literal, asp:DataList, set values etc in Page_PreRenderComplete. Basically, the asp:DataList wasn't being set in Page_Load, as expected, so doing any kind of logic in Page_Load based on the item count didn't make any sense.