I want to prevent customers entering PO Boxes into the shipping address for selected Shipping Methods (UPS specifically in this case). I could override js/prototype/validation.js to insert a new validation pattern, but I don't want to fork such a key file.
Is there a mechanism to unobtrusively validate the customer's shipping address AFTER they select a shipping method via Javascript without overriding core files?
I see that Validation.add is used inside the validation.js, so it may be possible to add a new validation method outside of the core file?
The regex that I want to apply is:
\b([P|p](OST|ost)?\.?\s?[O|o|0](ffice|FFICE)?\.?\s)?([B|b][O|o|0][X|x])\s(\d+)
If the validation cannot be performed elegantly in the JS, I would be interested in an Observer on the controller_action_predispatch_onepage_saveShippingMethod that inspects the data and performs an Ajax redirect back to the shipping address form if necessary.
The library used is Really Easy Field Validation and that page does explain how to extend it. I guess you will need something like this:
Validation.add('address', 'Error message text', {
pattern : /\b([P|p](OST|ost)?\.?\s?[O|o|0](ffice|FFICE)?\.?\s)?([B|b][O|o|0][X|x])\s(\d+)/
});