openproject/lib/api/v3/work_packages/eager_loading/hierarchy.rb

#-- encoding: UTF-8

#-- copyright
# OpenProject is an open source project management software.
# Copyright (C) 2012-2021 the OpenProject GmbH
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License version 3.
#
# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
# Copyright (C) 2006-2013 Jean-Philippe Lang
# Copyright (C) 2010-2013 the ChiliProject Team
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
#
# See docs/COPYRIGHT.rdoc for more details.
#++

module API
  module V3
    module WorkPackages
      module EagerLoading
        class Hierarchy < Base
          def apply(work_package)
            work_package.association(:children).loaded!
            work_package.association(:children).target = children(work_package.id)
          end

          private

          def children(id)
            @children ||= WorkPackage
                          .joins(:parent_relation)
                          .where(relations: { from_id: work_packages.map(&:id) })
                          .select(:id, :subject, :project_id, :from_id)
                          .group_by(&:from_id).to_h

            @children[id] || []
          end
        end
      end
    end
  end
end