Today I’ve had an extremely interesting realization: the number, order and exact point in the page lifecycle at which HtmlMeta controls are added to the HTML head can have significant implications for your page. Especially if you have some sort of “transient” meta tags that are only added to the page when it is initially loaded, but not after a postback. When you call the

myHeadControl.Controls.Add(myHtmlMetaControl)

method, every control that doesn’t have a manually set ID will be assigned an automatic ID by its naming container (ctl00, ctl01, …). This doesn’t seem too bad until you realize that this means that the ID of your very important custom control can change from “…ctl08…” during initial page load to “…ctl04…” in a postback. And THAT is a problem. Because the way that the view state is restored to the control tree is directly through those control IDs. Actual results can vary from mismatched control values to view state exceptions and lots of other hard-to-trace problems.

Continue reading Prevent automatically generated IDs for controls