• 3 min read

Smooth client-side routing in a figwheel-only project

One of the few things I missed when starting with re-frame was the excellent client-side routing setup you get with ember-cli, especially the development server part of that.

After some digging I found this fantastic article, No-hashes bidirectional routing in re-frame with silk and pushy, in which Pablo lays out all the Clojurescript required for nice push state based routing.

In the article though Pablo does note that he hasn't tried setting this up with a figwheel only project. I needed to figure this out for myself, and it turned out that my first journey into the wilderness was not nearly as daunting as I thought.

Browsing through the lein-figwheel docs I found a reference to providing your own ring-handler. Looking around further I noticed that Arne Brasseur's chestnut provides a custom ring-handler for a smoother development experience.

Using these hints I got it working fairly easily!

Project updates

First off, add the following dependencies to your project.clj

    [ring "1.4.0"]
    [ring/ring-defaults "0.2.0"]
    [compojure "1.5.0"]

Still in your project.clj, add a :ring-handler option to the fighweel settings like so:

    :figwheel {:css-dirs ["resources/public/css"]
               :ring-handler example.dev-server/http-handler}
               ;; ^-- THIS

Now it is time to create the dev-server, simply open up src/clj/example/dev_server.clj (making the parent directories and setting the right namespace) and drop in the following:

(ns example.dev-server
  (:require [clojure.java.io :as io]
            [compojure.core :refer [ANY defroutes]]
            [ring.middleware.defaults :refer [wrap-defaults site-defaults]]))

(defroutes routes
  (ANY "*" _
    {:status 200
     :headers {"Content-Type" "text/html; charset=utf-8"}
     :body (io/input-stream (io/resource "public/index.html"))}))

(def http-handler
  (-> routes
      (wrap-defaults site-defaults)))

Basically what this does is turn your index.html file into a 404 handler. The dev-server will serve up this file when figwheel can't find static assets in your project.

Deployment

Just for completeness sake, when deploying your figwheel build you'll need to add something like this to server directive in nginx:

server {
  location / {
    expires -1;

    try_files $uri $uri/ /index.html =404;
  }
}

That try_files directive does the same as our ring middleware. It turns your index.html into a glorified 404 handler.

Beware though to properly do 404 handling in your client-side application when you don't recognize the URL, or if a backend API returns a 404. You don't have nice status codes now, which may or may not matter to your app.

In closing

I'm sure there are many more ways to get this done, so do some research before just pasting my code in :). For one, maybe setting up the dependencies in the development profile in leiningen instead of a hard dependency for the entire project.

There are many small things like this that makes ember-cli shine. But we can bring those refinements across bit by bit. Then again, figwheel offers an amazing developer experience on its own.

At the moment though I can say I'm very happy with learning Clojure & ClojureScript. There is still so much to learn!

Image from REM online.

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