in lib/helpers.rb [30:42]
def source
@source ||= case params["source_type"]
when "user"
User.find_by(external_id: params["source_id"])
when "thread"
CommentThread.find(params["source_id"])
when "other"
Commentable.find(params["source_id"])
else
raise ArgumentError, t(:source_type_must_be_user_thread_or_other)
end
end