add optional context-fn setting

reagent-data-views-browserchannel/src/reagent_data_views/browserchannel/server.clj

@@ -8,11 +8,12 @@
 (defn configure-views!
   "performs browserchannel-specific initialization on the views system that is
    necessary to hook views and reagent-data-views together via browserchannel."
-  []
+  [& {:keys [context-fn]}]
   (views/set-send-fn!
     (fn [client-id [view-sig view-data]]
       (log/trace client-id "refresh view" view-sig)
-      (browserchannel/send-data! client-id [:views/refresh view-sig view-data]))))
+      (browserchannel/send-data! client-id [:views/refresh view-sig view-data])))
+  (server/set-context-fn! context-fn))
 
 (def middleware
   "clj-browserchannel server-side event middleware. this should be included in the

reagent-data-views/src/reagent_data_views/server/core.clj

@@ -4,25 +4,32 @@
     [views.core :as views]
     [reagent-data-views.utils :refer [relevant-event?]]))
 
+(defn- handle-subscriptions!
+  [client-id view-sig context]
+  (log/trace client-id "subscribing to" view-sig)
+  (views/subscribe! view-sig client-id context))
+
+(defn- handle-unsubscriptions!
+  [client-id view-sig context]
+  (log/trace client-id "unsubscribing from" view-sig)
+  (views/unsubscribe! view-sig client-id context))
+
+(defn- update-context
+  [existing-context]
+  (if-let [context-fn (get-in @views/view-system [:reagent-data-views :context-fn])]
+    (context-fn existing-context)
+    existing-context))
+
 (defn on-close!
   [client-id context]
   (log/trace client-id "on-close, unsubscribing from all views")
   (views/unsubscribe-all! client-id))
 
-(defn handle-subscriptions!
-  [client-id view-sig context]
-  (log/trace client-id "subscribing to" view-sig)
-  (views/subscribe! view-sig client-id context))
-
-(defn handle-unsubscriptions!
-  [client-id view-sig context]
-  (log/trace client-id "unsubscribing from" view-sig)
-  (views/unsubscribe! view-sig client-id context))
-
 (defn on-receive!
   [client-id data context]
   (when (relevant-event? data)
-    (let [[event view-sig] data
+    (let [context          (update-context context)
+          [event view-sig] data
           ; for safety, since this is otherwise coming in un-altered from clients
           view-sig         (dissoc view-sig :namespace)]
       (condp = event
@@ -31,3 +38,7 @@
         (log/warn client-id "unrecognized event" event "-- full received data:" data))
       ; indicating that we handled the received event
       true)))
+
+(defn set-context-fn!
+  [f]
+  (swap! views/view-system assoc-in [:reagent-data-views :context-fn] f))