Mongoid 2.0 Workaround Methods for Update/Delete actions when using references_and_referenced_in_many

gistfile1.rb

# tag.rb
class Tag
  include Mongoid::Document

  # Fields
  field :title

  # Associations
  references_and_referenced_in_many :related, :class_name => "Tag"
          
  before_save :flatten_related_tags # Needed for cases where related_ids == [[]]
  before_destroy :delete_from_related_tags
  before_destroy :delete_from_tagged_content

  private

  def delete_from_tagged_content
    [Article,Pdf,Link].each do |model|
      model.any_in(:tag_id => [self.id]).each do |item|
        item.tag_id.delete(self.id)
        item.save
      end
    end
  end
  
  def delete_from_related_tags
    Tag.any_in(:related_ids => [self.id]).each do |_tag|
      _tag.related.delete(self)
      _tag.save
    end
  end
  
  def flatten_related_tags
    if defined?(self.related_ids)
      self.related_ids.delete(self.id)
      self.related_ids.flatten!
      self.related_ids.uniq!
    end
  end
end

# tags_controller.rb
#
# Work around for fact that with Mongoid you cannot just use tag ids when setting relations. You have to work 
# with the actual tag object. So I can't just pass params[:tag][:related_ids] to update the @tag.related_ids property. 
# I have to convert the related_ids to related tags and update @tag.related.
def updateRelatedTags(current_tag, params_related_ids)
  # First compare the existing related ids with the ones passed as a param. If a currently stored related_id is 
  # missing from the params, it has been deleted as a related tag. So *that* tag needs to have *this* tag's relation
  # deleted as well.
  deleted_related_tags = (current_tag.related_ids || []) - (params_related_ids || [])
  if deleted_related_tags.any?
    deleted_related_tags.each do |related_tag_id|
      related_tag = Tag.criteria.for_ids(related_tag_id).first
      if !related_tag.nil?
        related_tag.related.delete(current_tag)
        related_tag.save
      end
    end
  end
  # Now update this tag's related tags using its related property, not its related_ids property. If you use the former 
  # the tag being related will not store a relation to this tag.
  if !params_related_ids.nil? && params_related_ids.any?
    params_related_ids.each do |related_tag_id|
      related_tag = Tag.criteria.for_ids(related_tag_id).first
      if !related_tag.nil?
        # This won't work if you try tag.related_ids.push(related_tag_id)
        current_tag.related.push(related_tag)
      end
    end
  else
    # No related ids were passed in, so there are no longer any relations
    current_tag.related = []
  end
end