Hydrating personal_collection_id should force creation of Personal Collections

src/metabase/models/collection.clj

@@ -1002,7 +1002,12 @@
   {:batched-hydrate :personal_collection_id}
   [users]
   (when (seq users)
+    ;; efficiently create a map of user ID -> personal collection ID
     (let [user-id->collection-id (db/select-field->id :personal_owner_id Collection
                                    :personal_owner_id [:in (set (map u/get-id users))])]
+      ;; now for each User, try to find the corresponding ID out of that map. If it's not present (the personal
+      ;; Collection hasn't been created yet), then instead call `user->personal-collection-id`, which will create it
+      ;; as a side-effect. This will ensure this property never comes back as `nil`
       (for [user users]
-        (assoc user :personal_collection_id (user-id->collection-id (u/get-id user)))))))
+        (assoc user :personal_collection_id (or (user-id->collection-id (u/get-id user))
+                                                (user->personal-collection-id (u/get-id user))))))))

test/metabase/models/collection_test.clj

@@ -7,14 +7,16 @@
              [card :refer [Card]]
              [collection :as collection :refer [Collection]]
              [dashboard :refer [Dashboard]]
-             [permissions :refer [Permissions] :as perms]
+             [permissions :as perms :refer [Permissions]]
              [permissions-group :as group :refer [PermissionsGroup]]
              [pulse :refer [Pulse]]
              [user :refer [User]]]
             [metabase.test.data.users :as test-users]
             [metabase.test.util :as tu]
             [metabase.util :as u]
-            [toucan.db :as db]
+            [toucan
+             [db :as db]
+             [hydrate :refer [hydrate]]]
             [toucan.util.test :as tt]))
 
 (defn force-create-personal-collections!
@@ -1460,6 +1462,13 @@
     (let [personal-collection (collection/user->personal-collection my-cool-user)]
       (db/update! Collection (u/get-id personal-collection) :personal_owner_id (test-users/user->id :crowberto)))))
 
+;; Does hydrating `:personal_collection_id` force creation of Personal Collections?
+(expect
+  (tt/with-temp User [temp-user]
+    (-> (hydrate temp-user :personal_collection_id)
+        :personal_collection_id
+        integer?)))
+
 
 ;;; +----------------------------------------------------------------------------------------------------------------+
 ;;; |                                    Moving Collections "Across the Boundary"                                    |