poll_session.rb

#
# Copyright (C) 2014 Instructure, Inc.
#
# This file is part of Canvas.
#
# Canvas is free software: you can redistribute it and/or modify it under
# the terms of the GNU Affero General Public License as published by the Free
# Software Foundation, version 3 of the License.
#
# Canvas 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 Affero General Public License for more
# details.
#
# You should have received a copy of the GNU Affero General Public License along
# with this program. If not, see <http://www.gnu.org/licenses/>.
#

module Polling
  class PollSession < ActiveRecord::Base
    belongs_to :course
    belongs_to :course_section
    belongs_to :poll, class_name: 'Polling::Poll'
    has_many :poll_submissions, class_name: 'Polling::PollSubmission', dependent: :destroy
    validates_presence_of :poll, :course
    validate :section_belongs_to_course

    set_policy do
      given do |user, session|
        self.poll.grants_right?(user, session, :update)
      end
      can :read and can :create and can :delete and can :publish

      given do |user, session|
        self.visible_to?(user, session)
      end
      can :read

      given do |user, session|
        self.visible_to?(user, session) && self.is_published?
      end
      can :submit
    end

    def self.available_for(user)
      PollSession.where("course_id IN (?) AND (course_section_id IS NULL OR course_section_id IN (?))",
                        Enrollment.where(user_id: user).active.select(:course_id),
                        Enrollment.where(user_id: user).active.select(:course_section_id))
    end

    def results
      poll_submissions.group('poll_choice_id').count
    end

    def has_submission_from?(user)
      poll_submissions.where(user_id: user).exists?
    end

    def publish!
      self.is_published = true
      save!
    end

    def close!
      self.is_published = false
      save!
    end

    def visible_to?(user, session)
      self.course.grants_right?(user, session, :read) &&
      (self.course_section ? self.course_section.grants_right?(user, session, :read) : true)
    end

    private
    def section_belongs_to_course
      if self.course && self.course_section
        unless self.course.course_sections.include?(course_section)
          errors.add(:base, I18n.t('polling.poll_sessions.validations.section_belongs_to_course',
                                   'That course section does not belong to the existing course.'))
        end
      end
    end
  end
end