Submitted by wesleydv on Sun, 08/05/2012 - 23:04
Drupal Commerce allows you to do a lot with rules, like add an extra product (productB) when adding a first product (productA).
But a user could off course delete the extra product (productB) in the cart. We could disable that button with some custom code but that could be unwanted.
Instead we're going to disable the checkout button with a simple hook_form_alter.
Simple and effective, but it would be even better if it could be done via a rule, maybe an idea for a contrib module.