ImageUrl lost on postback with dynamic controls, but textboxes keep their value

Question

I have a button that adds an already defined usercontrol programtically. I am rebuilding each control on Postback and they show up fine. If I put text in the textbox it shows up fine, however my images are losing their url. Any idea why or how I can fix this?

I tried adding AJAX updatepanel to see if that would help, but it does not.

To further explain - I have a button that after clicks set the url of the image - I also put this value in the textbox just to see if the same thing happens - after postback, my textbox still has the value, but the image does not - and all of my other ASP.Net images lose their image and they are defined right on the controls (ie: ImageUrl)

--- update OK, I have found some more insight to my issue - some solutions but still one problem remains.

The reason the images were loosing their url is because they were and not ASP.Net images - ASP.Net remembers the values when they are recreated on postback - however the Main image that im changing via javascript looses its value - I'm very certain this is because of using javascript to change it, on post back it reverts back to the previous value... so for a solution I will try to stuff it in a hidden value, then use that value on postback to define the ImageUrl of the image...

Answer 1

You are correct <img> is an html control, while <asp:Image> is a server control. As long as server controls have viewstate enabled they will keep their values during postbacks.

Answer 2

You are correct that changing an image's URL via JavaScript will not get it returned during the postback as this is not a form value. Therefore, it will be lost forever if you do not save it into a form field, such as the hidden field that you suggested.