context_module_item.rb

#
# Copyright (C) 2011 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/>.
#

# This isn't a record on its own, but a module included in other records such
# as Attachment and Assignment.
#
# ContextModules contain items indirectly, through ContentTags that contain the
# information on position in the module, progression requirements, etc.
module ContextModuleItem
  # set up the association for the AR class that included this module
  def self.included(klass)
    klass.has_many :context_module_tags, -> { where("content_tags.tag_type='context_module' AND content_tags.workflow_state<>'deleted'").preload(context_module: :content_tags) }, as: :content, inverse_of: :content, class_name: 'ContentTag'
  end

  # Check if this item is locked for the given user.
  # If we are locked, this will return the module item (ContentTag) that is
  # locking the item for the given user
  def locked_by_module_item?(user, opts = {})
    if self.context_module_tags.present? && self.context_module_tags.all? { |tag| tag.locked_for?(user, opts) }
      item = self.context_module_tags.first
    end
    item || false
  end

  # searches the ContextModuleItems in objs_to_search, in order, for the first
  # context module tag -- returns the tag with id preferred_id if given and it
  # exists
  #
  # If no preferred is found, but more than one tag exists for the same obj, we
  # return nothing, since we can't know which tag is appropriate to return.
  def self.find_tag_with_preferred(objs_to_search, preferred_id)
    preferred_id = preferred_id[Api::ID_REGEX] if preferred_id.is_a?(String)
    objs_to_search.each do |obj|
      next unless obj.present?
      tag = obj.context_module_tags.where(:id => preferred_id).first
      return tag if tag
    end
    objs_to_search.each do |obj|
      next unless obj.present?
      tags = obj.context_module_tags.to_a
      return nil if tags.size > 1
      tag = tags.first
      return tag if tag
    end
    return nil
  end
end