ASP.NET, controls added using .Controls.Add() are lost when page is posted back & if I add them using .InnerHtml I can't reference them

Question

I'm trying to make a comments page. I get previously made comments from a database, and there's a textbox for the new comment to be submitted. So in order to display the old comments from the database they have to be added dynamically, right? At first I was using something like: TheContainerControl.Controls.Add(TheComment), but it turns out that when the page is posted back (new comment submitted or something), everything I've dynamically added is gone! In order to work around this, I used TheContainerControl.InnerHtml("[html]") instead. That way, when the page is posted back the controls I've dynamically added aren't lost. However, I've been searching for nearly nine or ten hours now for a way to add event handlers to the controls I add via .InnerHtml and I haven't found anything :( I can't reference them at all, .FindControl() returns a null reference. I also tried to manually insert the code/script that would trigger the event, and miserably failed (I'm new to jQuery, and I know very little javascript). Please help if you can.

Answer 1

These old comments that you are adding back on the page, are these UI elements which respond to DOM events like click etc or are they merely lables which are there just for display? If they are merely there for display then as Brian said above you are better of using a Repeater r GridView or ListView instead of dynamic controls.

Actually even if they are control elements, you can still drop them in a template column in a GridView and let it handle the pagination etc. You can use jQuery live events to work with these controls.

Alternatively use ASP.NET Ajax and Update Panels to only refresh the part of the page that absolutely needs to be refreshed on a postback leaving the other parts intact.

It would be helpful if you can post some code.

Answer 2

The thing you have to keep in mind in Asp.net when dynamically adding controls to a page is the page life cycle. It is very particular about when you can add controls and still have them be persisted after the next postback. Or how late you can add controls and still have them render.

The common tendency for people building pages dynamically is to just start placing their code in the Page_Load() but this is too late in the life cycle. You might want to try the Init (or Page_Init).

As others have suggested, you may also consider not dynamically adding controls at all but instead sing some built in Asp.net content controls to manage the dynamic state of your page. When coming from other web frameworks/technologies where you can just build a page on the fly, Asp.net can seem a bit complicated. Just remember - once you learn to take advantage of the page life cycle and Asp.net controls you will not have to manually manage the state of all the elements on the page yourself.

Answer 3

It would be much easier to use a control like the Repeater, GridView, or ListView instead, which is built to display a dynamic number of comments.

Dynamic controls need to be added back to the page on every postback.

I'm not sure what you mean by: "I've been searching for nearly nine or ten hours now for a way to add event handlers to the controls I add via .InnerHtml and I haven't found anything :( I can't reference them at all, .FindControl() returns a null reference. I also tried to manually insert the code/script that would trigger the event, and miserably failed" - how does JQuery fit into this, are you trying to do this on client or server?

HTH.