through_record

# File activerecord/lib/active_record/associations/has_many_through_association.rb, line 52
        def through_record(record)
          through_association = owner.association(through_reflection.name)
          attributes = construct_join_attributes(record)

          through_record = Array.wrap(through_association.target).find { |candidate|
            candidate.attributes.slice(*attributes.keys) == attributes
          }

          unless through_record
            through_record = through_association.build(attributes)
            through_record.send("#{source_reflection.name}=", record)
          end

          through_record
        end