gistfile1.txt

(defn revert [id attrs opts]
  (sql/with-connection rev-log 
    (let [id     (Integer/parseInt (last (re-split #"-" id)))
          result (sql/with-query-results result 
                   ["UPDATE revisions
                     SET reverted_by = nextval('revision_id_seq'::regclass) 
                     WHERE id=? 
                     AND reverted_by IS NULL
                     returning reverted_by AS revision;"
                     id]
                    (first result))]
      (if result
        (log attrs opts)  
        (throw (Exception. "revision already reverted"))
        ))))