only define primary_key when not working with ActiveRecord
only define primary_key when not working with ActiveRecord

dcrec1/acts_as_solr_reloaded,tcjuan/acts_as_solr_reloaded,dcrec1/acts_as_solr_reloaded,coletivoEITA/acts_as_solr_reloaded,coletivoEITA/acts_as_solr_reloaded