What is the best way to find the corresponding controller

Question

I'm trying to fix a problem with having recurring simple products under a configurable product. I think I have found a solution provided by Magento: How to display recurring profile information for a configurable recurring product

My real question is, in Magento, how do you know which controller php file to edit? Or, am I completely misunderstanding procedure? I noticed Alan Storm's Commerce Bug, as one alternative. I also tried turning on the developer tools to enable template and block name path hints, which seems more helpful for design.

However, for the bug I'm trying to fix, how do you I know which php file to edit, as there are so many connected components (catalog, inventory, billing, etc.)?

This is a more procedural question, but feel free to comment on the specifics as well.

Answer 1

You can see which action controller is initially called by the url, that is always build up by: module/controller/action

i.e. when adding a product to the cart the url is: checkout/cart/add

So the controller you have to look at is at app/code/core/Mage/Checkout/controllers/CartController.php In there it's the addAction method.