Merge pull request #6638 from metabase/fix-ref-guide-db-call-explosion

Fix excessive DB calls on reference guide

src/metabase/api/database.clj

@@ -16,7 +16,7 @@
             [metabase.models
              [card :refer [Card]]
              [database :as database :refer [Database protected-password]]
-             [field :refer [Field]]
+             [field :refer [Field readable-fields-only]]
              [field-values :refer [FieldValues]]
              [interface :as mi]
              [permissions :as perms]
@@ -240,7 +240,7 @@
 
 (defn- autocomplete-suggestions [db-id prefix]
   (let [tables (filter mi/can-read? (autocomplete-tables db-id prefix))
-        fields (filter mi/can-read? (autocomplete-fields db-id prefix))]
+        fields (readable-fields-only (autocomplete-fields db-id prefix))]
     (autocomplete-results tables fields)))
 
 (api/defendpoint GET "/:id/autocomplete_suggestions"
@@ -285,7 +285,7 @@
   [id]
   (api/read-check Database id)
   (sort-by (comp str/lower-case :name :table) (filter mi/can-read? (-> (database/pk-fields {:id id})
-                                                                         (hydrate :table)))))
+                                                                       (hydrate :table)))))
 
 
 ;;; ----------------------------------------------- POST /api/database -----------------------------------------------

src/metabase/models/field.clj

@@ -10,6 +10,7 @@
             [metabase.util :as u]
             [toucan
              [db :as db]
+             [hydrate :refer [hydrate]]
              [models :as models]]))
 
 ;;; ------------------------------------------------------------ Type Mappings ------------------------------------------------------------
@@ -158,6 +159,13 @@
     (for [field fields]
       (assoc field :dimensions (get id->dimensions (:id field) [])))))
 
+(defn readable-fields-only
+  "Efficiently checks if each field is readable and returns only readable fields"
+  [fields]
+  (for [field (hydrate fields :table)
+        :when (i/can-read? field)]
+    (dissoc field :table)))
+
 (defn with-targets
   "Efficiently hydrate the FK target fields for a collection of FIELDS."
   {:batched-hydrate :target}
@@ -167,7 +175,7 @@
                                                (:fk_target_field_id field))]
                                 (:fk_target_field_id field)))
         id->target-field (u/key-by :id (when (seq target-field-ids)
-                                         (filter i/can-read? (db/select Field :id [:in target-field-ids]))))]
+                                         (readable-fields-only (db/select Field :id [:in target-field-ids]))))]
     (for [field fields
           :let  [target-id (:fk_target_field_id field)]]
       (assoc field :target (id->target-field target-id)))))