页面加载时未触发 defroute

Question

我在src/cljs/project/routes.cljs 根目录下的routes.cljs 文件中定义了应用程序路由。

(defn app-routes []
  (secretary/set-config! :prefix "#")

  (defroute
    "/" []
    (re-frame/dispatch [::events/set-active-panel :welcome-panel])))
  ; shortened for brevity

在core.cljs初始化

; required [portfolio-app.events :as events]
(defn ^:export init []
  (routes/app-routes)
  (re-frame/dispatch-sync [::events/initialize-db])
  (dev-setup)
  (mount-root))

它被分派到events.cljs中的::events/set-active-panel

(re-frame/reg-event-db
 ::set-active-panel
 (fn-traced [db [_ active-panel]]
   (assoc db :active-panel active-panel)))

并且在subs.cljs 订阅了:active-panel

(re-frame/reg-sub
 ::active-panel
 (fn [db _]
   (:active-panel db)))

我在layout.cljs 订阅了:active-panel

; required [portfolio-app.subs :as subs]
(defn panel []
  (let [active-panel (re-frame/subscribe [::subs/active-panel])]
    [:div
     "which panel? " @active-panel]))

@active-panel 在我第一次访问页面时是 nil。仅当我浏览页面时才调度面板。我知道这最初是有效的。我在我的提交中看不到任何可能破坏它的东西。

如何让我的defroutes 在页面加载以及通过网站导航时触发？

Answer 1

基于可用代码的几个猜测：

• 您是在页面加载时调用secretary/dispatch，还是仅在后续导航时调用？
• 您的::events/initialize-db 是否在正确设置:active-panel 后初始化数据库，导致您的订阅返回nil？

Answer 2

我怀疑您已经成为重新框架“陷阱”的受害者，其中像 events 这样的命名空间在编译过程中被省略，因为它没有在 (:require ...) 表单中列出。详情请见the Gotcha documentation。

为了使(:require ...) 更明确且更难忘记，我总是将所有(reg-event-* ...) 调用包装在一个从主程序初始化的更大函数中：

(ns demo.core  
  (:require 
     [demo.events :as events]
     [demo.subs :as subs]
     ...))

(defn app-start
  "Initiates the cljs application"
  []
  (events/define-all-events!)
  (subs/initialize-all)
  (configure-browser-routing!)
  ...)

然后：

(ns demo.events ...)
(defn define-all-events! []
  (reg-event-db ...)
  (reg-event-fx ...)
  ...)

我为秘书/会计路由以及定义订阅（即reg-sub）使用了类似的“将其包装在一个函数中”技术。例如：

(defn configure-browser-routing! []
  (println "configure-browser-routing - enter")

  (secretary/defroute "/all" []
    (println :secretary-route-all)
    (browser-nav-handler :all))
  (secretary/defroute "/active" []
    (println :secretary-route-active)
    (browser-nav-handler :active))
  (secretary/defroute "/completed" []
    (println :secretary-route-completed)
    (browser-nav-handler :completed))
  (secretary/defroute "/*" []
    (println ":secretary-route-all  *** default ***")
    (browser-nav-handler :all))

  (accountant/configure-navigation!
    {:nav-handler  (fn [path]
                     (t/spy :accountant--nav-handler--path path)
                     (secretary/dispatch! path))
     :path-exists? (fn [path]
                     (t/spy :accountant--path-exists?--path path)
                     (t/spy :accountant--path-exists?--result
                       (secretary/locate-route path)))})
  (println "configure-browser-routing - leave"))