_in_memory_query_constraints_hash

# File activerecord/lib/active_record/persistence.rb, line 868
      def _in_memory_query_constraints_hash
        if self.class.query_constraints_list.nil?
          { @primary_key => id }
        else
          self.class.query_constraints_list.index_with do |column_name|
            attribute(column_name)
          end
        end
      end