Felix Geisendorfer keeps it short and sweet in this latest post. He shares a regular expression to validate the output of the HtmlHelper method dateTimeOptionTag.

Ok, let's make this short and painless. I just needed to validate the (cleaned) output of an HtmlHelper::dateTimeOptionTag() to be a correct datetime value matching this format.

The regular expression is fairly simple (long, but simple) and he shows a simple way to include it into a model (in the special $validate array) to check the contents of the 'start' field).