Calculate flow interceptors earlier than user interceptors

Author: kimo-k

docs/releases/2024.md

@@ -6,6 +6,18 @@
 
 > The re-frame [Clojars page](https://clojars.org/re-frame/) contains dependency coordinates for Maven/deps/Lein.
 
+## 1.4.4 (2024-06-24)
+
+#### Changed
+
+    - Changed flows to calculate the new app-db earlier in the chain.
+      - Benefit:  user-defined interceptors can access post-flow app-db value.
+      - Drawback: they can't access the value of app-db directly resulting from the event handler.
+      - Drawback: they can't access flow-related effects like `:reg-flow`.
+
+    - Added a :re-frame/pre-flow-db key to the context
+      - This way, user-defined interceptors can still access the app-db value resulting directly from the event handler.
+
 ## 1.4.3 (2024-01-25)
 
 #### Fixed

src/re_frame/alpha.cljc

@@ -423,10 +423,10 @@
   ([id interceptors handler]
    (events/register id [cofx/inject-db
                         fx/do-fx
-                        flow/interceptor
-                        flow/do-fx
                         std-interceptors/inject-global-interceptors
                         interceptors
+                        flow/interceptor
+                        flow/do-fx
                         (db-handler->interceptor handler)])))
 
 (defn reg-event-fx
@@ -463,10 +463,10 @@
   ([id interceptors handler]
    (events/register id [cofx/inject-db
                         fx/do-fx
-                        flow/interceptor
-                        flow/do-fx
                         std-interceptors/inject-global-interceptors
                         interceptors
+                        flow/interceptor
+                        flow/do-fx
                         (fx-handler->interceptor handler)])))
 
 (defn reg-event-ctx
@@ -500,10 +500,10 @@
   ([id interceptors handler]
    (events/register id [cofx/inject-db
                         fx/do-fx
-                        flow/interceptor
-                        flow/do-fx
                         std-interceptors/inject-global-interceptors
                         interceptors
+                        flow/interceptor
+                        flow/do-fx
                         (ctx-handler->interceptor handler)])))
 
 (defn clear-event

src/re_frame/flow/alpha.cljc

@@ -165,8 +165,10 @@
 
 (def interceptor
   (->interceptor
-   {:id :flow
-    :after (fn [ctx]
-             (let [all-flows (with-cleared @flows)]
-               (swap! flows vary-meta dissoc ::cleared)
-               (reduce run ctx ((memoize topsort) all-flows))))}))
+   {:id    :flow
+    :after (comp (fn [ctx]
+                   (let [all-flows (with-cleared @flows)]
+                     (swap! flows vary-meta dissoc ::cleared)
+                     (reduce run ctx ((memoize topsort) all-flows))))
+                 (fn [{{:keys [db]} :effects :as ctx}]
+                   (assoc ctx :re-frame/pre-flow-db db)))}))