Return all transactions and all their datoms that have contributed to given entity

audit_trail.clj

(ns datomic-spike.audit-trail
  (:require [datomic.api :as d]))

(defn entity-txs
  "Accepts an entity, returns all transactions (as entities) that
  have altered the given entity, sorted by transaction t"
  [e]
  (let [id (:db/id e)
        db (d/entity-db e)
        history (d/history db)]
    (->> (d/q '[:find [?tx ...]
                :in $ ?e
                :where [?e _ _ ?tx]]
              history
              id)
         (sort-by d/tx->t)
         (map (partial d/entity db)))))

(defn tx-datoms
  "Accepts a connection and an entity of transaction. Returns all
  datoms of given transaction entity"
  [conn tx]
  (let [log (d/log conn)
        tx-id (:db/id tx)]
    (d/q '[:find ?e ?a ?v ?op
           :in ?log ?tx
           :where [(tx-data ?log ?tx) [[?e ?a ?v _ ?op]]]]
         log
         tx-id)))

(defn entity-audit-trail
  "Accepts a connection and an entity. Returns a seq of vectors of
  two elements, a transaction entity and a seq of datoms of the
  transaction. Transactions are entities and are ordered by
  transaction t."
  [conn e]
  (->> (entity-txs e)
       (map (fn [tx]
              [tx (tx-datoms conn tx)]))))

(comment

  (def uri (format "datomic:mem://test-%s" (d/squuid)))
  (d/create-database uri)
  (def c (d/connect uri))

  (do @(d/transact c [{:db/id (d/tempid :db.part/db)
                       :db/ident :audit/user
                       :db/valueType :db.type/string
                       :db/cardinality :db.cardinality/one
                       :db.install/_attribute :db.part/db}
                      {:db/id (d/tempid :db.part/db)
                       :db/ident :person/name
                       :db/valueType :db.type/string
                       :db/unique :db.unique/value
                       :db/cardinality :db.cardinality/one
                       :db.install/_attribute :db.part/db}
                      {:db/id (d/tempid :db.part/db)
                       :db/ident :person/email
                       :db/valueType :db.type/string
                       :db/cardinality :db.cardinality/one
                       :db.install/_attribute :db.part/db}
                      {:db/id (d/tempid :db.part/db)
                       :db/ident :person/tel
                       :db/valueType :db.type/string
                       :db/cardinality :db.cardinality/one
                       :db.install/_attribute :db.part/db}])
      @(d/transact c [{:db/id (d/tempid :db.part/user -1)
                       :person/name "Jarppe"
                       :person/email "foo@bar.com"}
                      [:db/add (d/tempid :db.part/tx) :audit/user "Matti"]])
      @(d/transact c [{:db/id [:person/name "Jarppe"]
                       :person/email "bar@bar.com"}
                      [:db/add (d/tempid :db.part/tx) :audit/user "Jarppe"]])
      @(d/transact c [{:db/id [:person/name "Jarppe"]
                       :person/tel "1234"}
                      [:db/add (d/tempid :db.part/tx) :audit/user "Matti"]])
      @(d/transact c [{:db/id [:person/name "Jarppe"]
                       :person/email "boz@bar.com"
                       :person/tel "321"}
                      [:db/add (d/tempid :db.part/tx) :audit/user "Petri"]])
      @(d/transact c [[:db/retract [:person/name "Jarppe"] :person/tel "321"]
                      [:db/add [:person/name "Jarppe"] :person/email "fofo@bar.com"]
                      [:db/add (d/tempid :db.part/tx) :audit/user "Mikko"]]))

  (entity-audit-trail c (d/entity (d/db c) [:person/name "Jarppe"]))

  (let [db (d/db c)
        audit-trail (entity-audit-trail conn (d/entity db [:person/name "Jarppe"]))]
    (doseq [[{:keys [:db/txInstant :audit/user]} datoms] audit-trail]
      (println txInstant user)
      (doseq [[e a v op] datoms]
        (println "   "
                 e
                 (->> a (d/entity db) :db/ident)
                 (pr-str v)
                 (if op "add" "retract")))))

  ; Prints:
  ;   #inst "2016-11-17T18:12:19.625-00:00" Matti
  ;       17592186045418 :person/name "Jarppe" add
  ;       17592186045418 :person/email "foo@bar.com" add
  ;       13194139534313 :audit/user "Matti" add
  ;       13194139534313 :db/txInstant #inst "2016-11-17T18:12:19.625-00:00" add
  ;   #inst "2016-11-17T18:12:19.627-00:00" Jarppe
  ;       17592186045418 :person/email "foo@bar.com" retract
  ;       13194139534315 :db/txInstant #inst "2016-11-17T18:12:19.627-00:00" add
  ;       13194139534315 :audit/user "Jarppe" add
  ;       17592186045418 :person/email "bar@bar.com" add
  ;   #inst "2016-11-17T18:12:19.628-00:00" Matti
  ;       17592186045418 :person/tel "1234" add
  ;       13194139534316 :audit/user "Matti" add
  ;       13194139534316 :db/txInstant #inst "2016-11-17T18:12:19.628-00:00" add
  ;   #inst "2016-11-17T18:12:19.629-00:00" Petri
  ;       17592186045418 :person/email "bar@bar.com" retract
  ;       17592186045418 :person/tel "321" add
  ;       17592186045418 :person/email "boz@bar.com" add
  ;       13194139534317 :db/txInstant #inst "2016-11-17T18:12:19.629-00:00" add
  ;       13194139534317 :audit/user "Petri" add
  ;       17592186045418 :person/tel "1234" retract
  ;   #inst "2016-11-17T18:12:19.631-00:00" Mikko
  ;       13194139534318 :db/txInstant #inst "2016-11-17T18:12:19.631-00:00" add
  ;       13194139534318 :audit/user "Mikko" add
  ;       17592186045418 :person/email "fofo@bar.com" add
  ;       17592186045418 :person/tel "321" retract
  ;       17592186045418 :person/email "boz@bar.com" retract

  
  (d/release c)
  (d/delete-database uri)
  )