join.cljs

(def PACKAGE-ID s/Int)

(def PACKAGE
  {:id PACKAGE-ID
   :url s/Str
   :inner_title s/Str})
 
(def db-schema
  {:package-ids [PACKAGE-ID]
   :package/by-id {PACKAGE-ID PACKAGE}})
 
;; probably not that efficient (if I understand correctly)

(register-sub
 :packages
 (fn [db _]
   (reaction (mapv (:package/by-id @db) (:packages @db)))))
   
;; should be better (mapv will not be run on each @db change)

;; ...trivial :package/by-id and :package-ids subscriptions...

(register-sub
 :packages-better
 (fn [db _]
   (let [package-by-id (subscribe [:package/by-id)])
         package-ids (subscribe [:package-ids])]
     (reaction (mapv package-by-id package-ids))))