How to access Form controls on Postback from Dynamically built form.

Question

I'm adding controls at run-time to the Page Form object.

Each control has an Id.

On postback, I want to be able to access these controls and their values.

Currently, when I do a postback, the form has no controls in the Form.Controls Collection.

How can I rectify this?

Is this only possible if you add the controls to the page every time the page loads?

Answer 1

I believe you have to add the controls dynamically in order to access them on postback. So if you add a textbox dynamically, your event handler can't retrieve its value unless you add it again.

EDIT: One workaround I used was to add a predetermined set of server controls to the page and then use JavaScript to hide/show those elements. You avoid postbacks and you avoid the unnecessary tom-foolery associated with retrieving values from dynamically added server controls. Of course, this limits you to a predefined number of controls.

This was a big pet peeve of mine with ASP.NET web forms and is a factor in my decision to explore ASP.NET MVC - no more viewstate/postback mess.

Answer 2

Dynamically added controls need to be added with every page load or else they will be lost.

However the viewstate of these controls can be maintained as long as they always get added with the same ID.