instantiate

# File activerecord/lib/active_record/associations/join_dependency.rb, line 132
      def instantiate(result_set, aliases)
        primary_key = aliases.column_alias(join_root, join_root.primary_key)

        seen = Hash.new { |h,parent_klass|
          h[parent_klass] = Hash.new { |i,parent_id|
            i[parent_id] = Hash.new { |j,child_klass| j[child_klass] = {} }
          }
        }

        model_cache = Hash.new { |h,klass| h[klass] = {} }
        parents = model_cache[join_root]
        column_aliases = aliases.column_aliases join_root

        message_bus = ActiveSupport::Notifications.instrumenter

        payload = {
          record_count: result_set.length,
          class_name: join_root.base_klass.name
        }

        message_bus.instrument('instantiation.active_record', payload) do
          result_set.each { |row_hash|
            parent_key = primary_key ? row_hash[primary_key] : row_hash
            parent = parents[parent_key] ||= join_root.instantiate(row_hash, column_aliases)
            construct(parent, join_root, row_hash, result_set, seen, model_cache, aliases)
          }
        end

        parents.values
      end