Google Shopping feed GTIN fix

Custom Prestashop ecommerce site Curiouser and Curiouser forced a tweak to the google merchant feed module to cater for the number of hand-made and art products that normally don’t have GTIN or EAN codes (barcodes) for the UK. Normally you need to have the requisite number of unique product identifiers to get listed in the shopping search results, as well as meeting the standards for google shopping adwords but as it says in the text:

“Exception: In categories where unique product identifiers are required but no such identifier exists for an item (e.g. custom goods), submit ‘identifier exists’ with a value of FALSE.”

So, in the module script that generates to feed, this warranted a condition to be added to check if the field was empty and if so, replace non-existent GTINs, e.g.:

<g:gtin></g:gtin>

with

<g:identifier_exists>false</g:identifier_exists>

Seems to work