What's the correct approach to debugging a pedestal.io app?

Question

I'm currently trying to reimplement the todo example app to understand how it works and I'm getting an error when I load the page. I'm not certain how to go from here. What concerns me is the error appears to be in cljs.core.

todo-app.simulated.services.receive_messages = (function receive_messages(app){
  return io.pedestal.app.protocols.put_message.call(null,(new cljs.core.Keyword("\uFDD0:input")).call(null,app),cljs.core.PersistentArrayMap.fromArray([io.pedestal.app.messages.type,"\uFDD0:create-todo",io.pedestal.app.messages.topic,cljs.core.PersistentVector.fromArray(["\uFDD0:todo"], true)], true));
});

The exception message is:

Uncaught TypeError: Object function (meta,cnt,arr,__hash){
this.meta = meta;
this.cnt = cnt;
this.arr = arr;
this.__hash = __hash;
this.cljs$lang$protocol_mask$partition1$ = 4;
this.cljs$lang$protocol_mask$partition0$ = 16123663;
} has no method 'fromArray'

And my dependencies are:

[[org.clojure/clojure "1.5.1"]
 [org.clojure/clojurescript "0.0-1820"]
 [domina "1.0.1"]
 [ch.qos.logback/logback-classic "1.0.7" :exclusions [org.slf4j/slf4j-api]]
 [io.pedestal/pedestal.app "0.1.9"]
 [io.pedestal/pedestal.app-tools "0.1.9"]]

Any help or insight would be appreciated!

bostonou · Answer 1 · 2013-07-18T01:33:52.967

I was seeing this error too, and it seemed like it came out of nowhere. Clearing the out/ dir (:target-path in your project.clj) fixed it for me. Based off that, I think there was some disconnect in the cljs compilation process and/or pedestal.

This issue looks similar and the fix was similar, so I assume it's a cljs build problem.

I don't have much to offer regarding pedestal debugging in general, but if I see an error that appears to be in a core library, I start from the assumption that something is wrong on my end. :)

EDIT

A little more info, it's recommended to delete the out\ dir every time you upgrade ClojureScript or Pedestal.

score 1 · Answer 2 · edited May 23 '17 at 12:09

As bostonou suggested, the best approach is deleting the out directory. My current approach is to use lein-cljsbuild, I personally do this by adding it to my user profile.

You can do so by calling nano ~/.lein/profiles.clj

Mine currently looks like:

{:user {:plugins [[lein-difftest "2.0.0"]
                  [lein-marginalia "0.7.1"]
                  [lein-pprint "1.1.1"]
                  [lein-swank "1.4.4"]
                  [lein-catnip "0.5.1"]
                  [environ/environ.lein "0.3.0"]
                  [lein-cljsbuild "0.3.2"]]
        :hooks [environ.leiningen.hooks]}}

You can now automatically build cljs files by calling lein-cljsbuild once inside the project folder. Calling lein-cljsbuild auto ensures that when the source files are edited then they are automatically compiled.

I also currently add :hooks [leiningen.cljsbuild] to my project.clj so that calling lein clean will also remove files built by lein-cljsbuild.

What's the correct approach to debugging a pedestal.io app?

2 Answers2