pluck_api.clj

  (let [conn       (-> system :database :connection)
        blob-store (-> system :blob-store)
        db         (d/db conn)
        env        {:db db :blob-store blob-store}]

    (defmulti -pluck
      "Multimethod for extending datomic.api/pull, while still maintaining the ability
      to let the query decied what is actually fetched."
      (fn [k env pull-result] k))

    ;; Default case just delivers what datomic.api/pull gives you.
    (defmethod -pluck :default [k env pull-result]
      (get pull-result k))

    (defn pick
      "Recursively annotates the pull-result with values supplied from the `-pluck`
      multimethod."
      [env pattern pull-result]
      (->> pattern
           (map (fn [k]
                  [(cond
                     (keyword? k) k
                     (map? k)     (-> k keys first))
                   (cond
                     (keyword? k) (-pluck k env pull-result)

                     (and (map? k)
                          (vector? (get pull-result (-> k keys first))))
                     (mapv #(pick env (-> k vals first) %) (get pull-result (-> k keys first)))

                     (and (map? k))
                     (pick env (-> k vals first) (get pull-result (-> k keys first))))]))
           (into {})))

    (defn pluck [env pattern eid]
      (let [pull-result (d/pull (:db env) pattern eid)]
        (pick env pattern pull-result)))


    ;;; Extend the pluck API by implementing -pluck multimethod.

    ;; dashboard/created-at is a derived attribute from Datomic's time model.
    (defmethod -pluck :dashboard/created-at [k {db :db} {eid :db/id}]
      (d/q '[:find
             ?created-at .
             :in $ ?d
             :where
             [?d :dashboard/organization _ ?org-tx _]
             [?org-tx :db/txInstant ?created-at]]
           db
           eid))

    ;; data-source/current-stream is stored in both Datomic and a separate blob-store.
    (defmethod -pluck :data-source/current-stream
      [k {:keys [db blob-store]} {ds-eid :db/id}]
      (let [data-stream     (-> (d/entity db ds-eid) :data-source/current-stream)
            data-stream-eid (:db/id data-stream)
            uuid            (:data-stream/id data-stream)]
        (merge (d/pull db [{:data-stream/status [:db/ident]} :data-stream/id] data-stream-eid)
               (data-stream/find-by-id blob-store uuid))))

    ;; data-source/fields need to be post-processed.
    (defmethod -pluck :data-source/fields [k {db :db} pull-result]
      (read-string (get pull-result :data-source/fields-str)))

    (pluck env
           [:db/id
            :dashboard/created-at
            {:dashboard/author [:db/id :user/first-name :user/last-name]}
            :dashboard/title
            {:dashboard/widgets [:db/id
                                 :widget/title
                                 {:widget/data-source [:db/id
                                                       :data-source/id
                                                       :data-source/fields
                                                       :data-source/current-stream
                                                       :data-source/fields-str]}]}]
           17592186056144))

;;; Returns something like
{:db/id 17592186056144,
 :dashboard/created-at #inst "2016-06-25T00:06:14.571-00:00",
 :dashboard/author
 {:db/id 17592186045435, :user/first-name "Clark", :user/last-name "Gates-George"},
 :dashboard/title "Summary Statistics",
 :dashboard/widgets
 [{:db/id 17592186056448,
   :widget/title "bar copyxx",
   :widget/data-source
   {:db/id 17592186056450,
    :data-source/id #uuid "57719b0b-e736-49c2-8410-f7d572c058ce",
    :data-source/fields ["clicks" "spend" "impressions" "ctr"],
    :data-source/current-stream
    {:data-stream/status {:db/ident :data-stream.status/ready},
     :data-stream/id #uuid "577eedab-386f-4de8-932f-93cf52a547cc",
     :data-stream/start-date "2016-06-01",
     :data-stream/end-date "2016-06-30",
     :data-stream/filtered-totals
     {:row/metrics
      {"impressions" "900,019",
       "ctr" "0.51%",
       "clicks" "4,630",
       "spend" "$13,263.14 USD"},
      :row/meta {"currency_code" "USD", "currency_symbol" "$"},
      :row/row-id "totals"}},
    :data-source/fields-str "[\"clicks\" \"spend\" \"impressions\" \"ctr\"]"}}
  {:db/id 17592186056490,
   :widget/title "bar copy copy",
   :widget/data-source
   {:db/id 17592186056492,
    :data-source/id #uuid "57719c44-ef52-4ad6-abd6-534aedf63cb9",
    :data-source/fields ["clicks" "spend" "impressions" "ctr"],
    :data-source/current-stream
    {:data-stream/status {:db/ident :data-stream.status/ready},
     :data-stream/id #uuid "57729c65-23bf-4dfc-bdd3-ca59a3e1c232",
     :data-stream/start-date "2016-05-01",
     :data-stream/end-date "2016-05-31",
     :data-stream/filtered-totals
     {:row/metrics
      {"impressions" "983,378",
       "ctr" "0.37%",
       "clicks" "3,609",
       "spend" "$11,760.04 USD"},
      :row/meta {"currency_code" "USD", "currency_symbol" "$"},
      :row/row-id "totals"}},
    :data-source/fields-str "[\"clicks\" \"spend\" \"impressions\" \"ctr\"]"}}
  {:db/id 17592186056499,
   :widget/title "",
   :widget/data-source
   {:db/id 17592186056501,
    :data-source/id #uuid "57719c60-1891-44d0-95b2-52af308daa65",
    :data-source/fields ["spend" "clicks" "impressions" "ctr"],
    :data-source/current-stream
    {:data-stream/status {:db/ident :data-stream.status/ready},
     :data-stream/id #uuid "57729c65-5541-4b80-acac-0af98bf02504",
     :data-stream/start-date "2016-05-01",
     :data-stream/end-date "2016-05-31",
     :data-stream/filtered-totals
     {:row/metrics
      {"impressions" "983,378",
       "ctr" "0.37%",
       "clicks" "3,609",
       "spend" "$11,760.04 USD"},
      :row/meta {"currency_code" "USD", "currency_symbol" "$"},
      :row/row-id "totals"}},
    :data-source/fields-str "[\"spend\" \"clicks\" \"impressions\" \"ctr\"]"}}
  {:db/id 17592186056504,
   :widget/title "bar copyxx copy",
   :widget/data-source
   {:db/id 17592186056506,
    :data-source/id #uuid "57719c76-9a4e-4e3f-a57d-7760cfbef9dc",
    :data-source/fields ["clicks" "spend" "impressions" "ctr"],
    :data-source/current-stream
    {:data-stream/status {:db/ident :data-stream.status/ready},
     :data-stream/id #uuid "57729c65-fc6b-4e2c-ba43-72902145d808",
     :data-stream/start-date "2016-05-01",
     :data-stream/end-date "2016-05-31",
     :data-stream/filtered-totals
     {:row/metrics
      {"impressions" "983,378",
       "ctr" "0.37%",
       "clicks" "3,609",
       "spend" "$11,760.04 USD"},
      :row/meta {"currency_code" "USD", "currency_symbol" "$"},
      :row/row-id "totals"}},
    :data-source/fields-str "[\"clicks\" \"spend\" \"impressions\" \"ctr\"]"}}
  {:db/id 17592186056548,
   :widget/title "bar copyxx copy",
   :widget/data-source
   {:db/id 17592186056550,
    :data-source/id #uuid "5771bfac-aaf9-4273-a8b4-fb82447c8cd1",
    :data-source/fields ["clicks" "spend" "impressions" "ctr"],
    :data-source/current-stream
    {:data-stream/status {:db/ident :data-stream.status/ready},
     :data-stream/id #uuid "57729c65-8333-4010-87da-522619ed4305",
     :data-stream/start-date "2016-05-01",
     :data-stream/end-date "2016-05-31",
     :data-stream/filtered-totals
     {:row/metrics
      {"impressions" "983,378",
       "ctr" "0.37%",
       "clicks" "3,609",
       "spend" "$11,760.04 USD"},
      :row/meta {"currency_code" "USD", "currency_symbol" "$"},
      :row/row-id "totals"}},
    :data-source/fields-str "[\"clicks\" \"spend\" \"impressions\" \"ctr\"]"}}]}