Rewrite sources in all joined-fields (#12161)

src/metabase/driver/sql/query_processor.clj

@@ -812,7 +812,7 @@
 ;;; -------------------------------------------- putting it all togetrher --------------------------------------------
 
 (defn- expressions->subselect
-  [{:keys [expressions fields] :as query}]
+  [{:keys [expressions] :as query}]
   (let [subselect (-> query
                       (select-keys [:joins :source-table :source-query :source-metadata])
                       (assoc :fields
@@ -823,14 +823,12 @@
                                  (mbql.u/replace expression-definition
                                    [:expression expr] (expressions (keyword expr)))])
                               (distinct
-                               (mbql.u/match query [(_ :guard #{:field-literal :field-id :joined-field}) & _])))))
-        ;; TODO -- correctly handle fields in multiple tables with the same name
-        fields    (mbql.u/replace fields
-                    [:joined-field alias field] [:joined-field "source" field])]
+                               (mbql.u/match query [(_ :guard #{:field-literal :field-id :joined-field}) & _])))))]
     (-> query
+        ;; TODO -- correctly handle fields in multiple tables with the same name
+        (mbql.u/replace [:joined-field alias field] [:joined-field "source" field])
         (dissoc :source-table :source-query :joins :expressions :source-metadata)
-        (assoc :source-query subselect
-               :fields       fields))))
+        (assoc :source-query subselect))))
 
 (defn- apply-clauses
   "Like `apply-top-level-clauses`, but handles `source-query` as well, which needs to be handled in a special way

test/metabase/query_processor_test/expressions_test.clj

@@ -242,3 +242,25 @@
                       :limit       3
                       :order-by    [[:asc $name]]})
                    mt/rows)))))))
+
+
+;;; +----------------------------------------------------------------------------------------------------------------+
+;;; |                                     JOINS                                                                      |
+;;; +----------------------------------------------------------------------------------------------------------------+
+
+(deftest expressions+joins-test
+  (datasets/test-drivers (mt/normal-drivers-with-feature :expressions)
+    (testing "Do calculated columns play well with joins"
+      (is (= "Quentin Sören"
+             (-> (mt/run-mbql-query checkins
+                   {:expressions {:prev_month [:+ $date [:interval -31 :day]]}
+                    :fields      [[:joined-field "users__via__user_id" [:field-id (data/id :users :name)]]
+                                  [:expression :prev_month]]
+                    :limit       1
+                    :joins       [{:strategy :left-join
+                                   :source-table (data/id :users)
+                                   :alias        "users__via__user_id"
+                                   :condition    [:= $user_id
+                                                  [:joined-field "users__via__user_id" [:field-id (data/id :users :id)]]]}]})
+                 mt/rows
+                 ffirst))))))