I recently had the opportunity to work on a piece of code that was to accept a couple of values based on a couple of drop-down selectors. The second of the selectors needed to be relative to the value selected in the first one. This was part of a project that uses the Zend Framework. In order to not compromise my NDA, I am changing the particulars, but the nature of the task remains true. To that end, I will start by setting the environment. As stated, I am using the Zend Framework and implementing the MVC design pattern that ZF is known for. I am using the Zend_Layout extension and have the standard application/layouts/scripts folder with a “layout.phtml” file containing my overall layout. I am using just the Controller/Action setup rather than the Module/Controller/Action one, so if you are utilizing modules, then you will need to adjust this to your environment. I also use Zend_Form to create my form input and you will see some example code based on this a little later that will show two drop-down selectors defined on a form. The first drop-down selector will be called Category and the second drop-down selector will be called SubCategory. I know, how original! So, now that the background is laid out, lets start by defining the solution I am setting out to accomplish here.