convert_to_id

# File activerecord/lib/active_record/relation/predicate_builder/polymorphic_array_value.rb, line 44
        def convert_to_id(value)
          if value.is_a?(Base)
            primary_key = primary_key(value)
            if primary_key.is_a?(Array)
              primary_key.map { |column| value._read_attribute(column) }
            else
              value._read_attribute(primary_key)
            end
          elsif value.is_a?(Relation)
            value.select(primary_key(value))
          else
            value
          end
        end