Re-Frame accepts nil in :dispatch-n vector but re-frame-flow fails to handle it and throws errors.

[CalebMacdonaldBlack]

I can pass nil into :dispatch-n fx vector successfully with re-frame but re-frame-flow fails to deal with this

https://github.com/day8/re-frame/blob/ecb756e66fe30efca896879369a420df1e271605/src/re_frame/fx.cljc#L147

(reg-fx
  :dispatch-n
  (fn [value]
    (if-not (sequential? value)
      (console :error "re-frame: ignoring bad :dispatch-n value. Expected a collection, but got:" value)
      (doseq [event (remove nil? value)] (router/dispatch event)))))

I get errors because of a nil id param being passed into these two re-frame-flow.core functions:

(defn- kw->str [id]
  (if (qualified-keyword? id)
    (str (namespace id) "/" (name id))
    (name id)))


(defn- id->node [id]
  {:id (kw->str id)
   :style {:fontSize 14
           :fontFamily "monospace"
           :wordBreak "break-word"
           :width 200}
   :data {:label id
          :name (name id)
          :namespace (namespace id)}
   :sourcePosition "right"
   :targetPosition "left"
   :position {:x 0 :y 0}})

[ertugrulcetin]

Thanks for reaching out @CalebMacdonaldBlack. What is the exact error are you getting? Also, could you send your code snippet that causes the error? I tried passing nil to dispatch-n and did not get any errors;

(reg-event-fx
  ::call-some-stuff
  (fn [{:keys [db]} _]
    {:dispatch-n nil}))

Also, the code ignores if the dispatch-n is nil: https://github.com/ertugrulcetin/re-frame-flow/blob/master/src/re_frame_flow/core.cljc#L27

So nil shouldn't pass these functions, I need more info about this one.

[CalebMacdonaldBlack]

Hi @ertugrulcetin. I love your project! Thank you for making it.

the dispatch-n takes a vector. Run this and you should see the error in your console:

(rf/reg-event-fx
  :foo
  (fn [_ _]
    {:dispatch-n [nil]}))

(rf/dispatch [:foo])

Here's the stack trace though:

router.cljc:204 Uncaught Error: Doesn't support name: 
    at Object.cljs$core$name [as name] (core.cljs:9500)
    at Object.re_frame_flow$core$kw__GT_str [as kw__GT_str] (core.cljc:57)
    at re_frame_flow$core$id__GT_node (core.cljc:68)
    at eval (core.cljs:4712)
    at eval (core.cljs:4712)
    at Object.eval [as sval] (core.cljs:3415)
    at Object.eval [as cljs$core$ISeqable$_seq$arity$1] (core.cljs:3472)
    at Object.cljs$core$seq [as seq] (core.cljs:1213)
    at eval (core.cljs:3770)
    at Object.eval [as sval] (core.cljs:3415)

The event key is nil and name cannot accept nil as a value. Re-frame deals with nil values here by filtering them out before dispatching them.

[ertugrulcetin]

@CalebMacdonaldBlack thank you for the detailed explanation. I fixed it and released a new version "0.1.3", please try it. If some error occurs, let me know.