gistfile1.txt

; datomic func  
[{:db/id #db/id [:db.part/user]
  :db/ident :person/namer
  :db/doc "ensures unique name"
  :db/fn #db/fn {:lang "clojure"
                 :params [db oid name]
                 :code "(let [ e (datomic.api/q
                                 '[:find ?e
                                   :in $ ?oid ?name
                                   :where
                                   [?e :person/name ?name]
                                   [?e :person/organization ?oid]]
                                db oid name )]
                        (when-not (ffirst e )
                          (let [id (datomic.api/tempid :db.part/user)]
                            [[:db/add id :person/name name]
                             [:db/add id :person/organization oid]])))" }}]
                             
  ; clojure func 
  (defn get-or-create-person [oid name]
  (let [unique-name @(d/transact @db/conn [[:person/namer oid name]])
        person-ent (d/q
                    '[:find ?e
                      :in $ ?oid ?name
                      :where
                      [?e :person/name ?name]
                      [?e :person/organization ?oid]]
                    (db/_d) oid name) ]
    (ffirst person-ent)))
    
    ; test 
  (deftest it-has-a-thread-safe-get-or-create
    (let [{:keys [user req]} (stub-it)
        name "John Reilly"
        params (map
                (fn [_]
                  [(:db/id user) name])
                (range 10))
        tx (pmap (fn [param]
                   (people/get-or-create-person (:db/id user) name)
                   ) params)]
    (is (apply = tx))))