Clear dimension data when the special_type is not supported

If a field is set to an enum or category type and has a remapping,
that should be cleared if the field moves to a special_type that is
not allowed to have remappings (i.e. text). This commit adds checks
for that and clears the dimension in that case.

src/metabase/api/field.clj

@@ -40,6 +40,23 @@
        (or (nil? new-special-type)
            (not (isa? new-special-type :type/FK)))))
 
+(defn- internal-remapping-allowed? [base-type special-type]
+  (and (isa? base-type :type/Integer)
+       (or
+        (nil? special-type)
+        (isa? special-type :type/Category)
+        (isa? special-type :type/Enum))))
+
+(defn- clear-dimension-on-type-change!
+  "Removes a related dimension if the field is moving to a type that
+  does not support remapping"
+  [{{old-dim-id :id, old-dim-type :type} :dimensions, :as old-field} base-type new-special-type]
+  (when (and old-dim-id
+             (= :internal old-dim-type)
+             (not (internal-remapping-allowed? base-type new-special-type)))
+    (db/delete! Dimension :id old-dim-id))
+  true)
+
 (api/defendpoint PUT "/:id"
   "Update `Field` with ID."
   [id :as {{:keys [caveats description display_name fk_target_field_id points_of_interest special_type visibility_type], :as body} :body}]
@@ -67,6 +84,7 @@
         (if removed-fk?
           (clear-dimension-on-fk-change! field)
           true)
+        (clear-dimension-on-type-change! field (:base_type field) new-special-type)
         (db/update! Field id
           (u/select-keys-when (assoc body :fk_target_field_id (when-not removed-fk? fk-target-field-id))
             :present #{:caveats :description :fk_target_field_id :points_of_interest :special_type :visibility_type}

test/metabase/api/field_test.clj

@@ -501,3 +501,38 @@
           after-change  (simple-field-details (Field field-id-2))]
       [(tu/boolean-ids-and-timestamps before-change)
        (tu/boolean-ids-and-timestamps after-change)])))
+
+;; Changing a remapped field's type to something that can't be remapped will clear the dimension
+(expect
+  [{:id true
+    :created_at true
+    :updated_at true
+    :type :internal
+    :name "some dimension name"
+    :human_readable_field_id false
+    :field_id true}
+   []]
+  (tt/with-temp* [Field [{field-id :id} {:name "Field Test"
+                                         :base_type "type/Integer"}]]
+    (dimension-post field-id {:name "some dimension name", :type "internal"})
+    (let [new-dim (dimension-for-field field-id)]
+      ((user->client :crowberto) :put 200 (format "field/%d" field-id) {:special_type "type/Text"})
+      [(tu/boolean-ids-and-timestamps new-dim)
+       (dimension-for-field field-id)])))
+
+;; Change from supported type to supported type will leave the dimension
+(expect
+  (repeat 2 {:id true
+             :created_at true
+             :updated_at true
+             :type :internal
+             :name "some dimension name"
+             :human_readable_field_id false
+             :field_id true})
+  (tt/with-temp* [Field [{field-id :id} {:name "Field Test"
+                                         :base_type "type/Integer"}]]
+    (dimension-post field-id {:name "some dimension name", :type "internal"})
+    (let [new-dim (dimension-for-field field-id)]
+      ((user->client :crowberto) :put 200 (format "field/%d" field-id) {:special_type "type/Category"})
+      [(tu/boolean-ids-and-timestamps new-dim)
+       (tu/boolean-ids-and-timestamps (dimension-for-field field-id))])))