We need to add some google product feed additional fields to our variable products. (String) fields such as: UPC code, google product category, google custom field 0, google promotion id.
We don’t want to use a plug-in unless necessary since the current one we use (google product feed) serializes the data and makes it hard to work with when importing, exporting, editing data. snapshot of current plug in fields: http://imgur.com/a/mTGvE
Do we have to create this functionality ourselves using an approach like one of these articles outlines?