Problems reloading the viewstate of my dynamically created ASP.Net controls.

Question

I have an ajax toolkit tab container on my ASP.Net page, and I am dynamically creating the tabs in the code behind (at runtime, I have a variable number of tabs, each with the same layout but different header text and body data). Each tab contains only one control, which is a user control I built to make all the tabs look the same. In the user control is another user control I built to handle the paging of my data within the tab. That paging user control has a property that is backed its ViewState.

I bind all the data for the tabs in a single BindData function on the ASPX page. Within that function, I am always setting an ID for my dynamically created controls and adding them to their container controls before setting any other properties, wiring events, or binding data to them.

I am losing the ViewState variable's value in my paging user control in this scenario:

main ASPX page

Page_Init:

    If IsPostBack Then
        BindData     ' Recreates the control tree on postback.
        ' ViewState is loaded successfully here.
    End If

Page_Load:

    If Not IsPostBack Then
        BindData()   ' Bind the initial data.
    End If

[Some event that happens after Page_Load in response to clicking on my user control]:

    ...
    BindData()    ' Controls recreated with changed data but same IDs as in Page_Init.
    ' ViewState does not get loaded back into my control tree.

Should I not expect the ViewState to get loaded again on the second version of my control tree in the page lifecycle?

Answer 1

You should create the dynamic controls in pre-init phase. And recreate them even after postback. Check the details of the page lifecycle here: http://msdn.microsoft.com/en-us/library/ms178472.aspx

Answer 2

After much reading, it seems like any dynamic controls created after the Init phase do not load the ViewState. For my situation, in my BindData function, I grab my viewstate values to local variables, recreate the controls, and then reset the viewstate values. This seems to work.