gistfile1.txt

 def create
    @project = Project.find(params[:project_id])
    @document = Document.find(params[:document_id])
    @version = DocumentVersion.new(version_params)
    authorize_action_for(@version, parent_project)
    if !params[:version][:file].blank?
      @version.file.add_meta('attachable_type' => @document.class.to_s)
      @version.file.add_meta('attachable_uid' => @document.id.to_s)
      @version.file.add_meta('project_uid' => params[:project_id])
    end
    @document.document_versions << @version