A tiny, zero dependency, system-agnostic router for Clojure, ClojureScript, Babashka and NBB that operates with a simple data structure where each route is a map inside a vector. Yup, that's it. No magic, no bullshit.

• Routing with Ruuter in a Reagent / Re-frame project

Require the namespace ruuter.core and then pass your routes to the route function along with the current request map, like this:

(ns myapp.core
  (:require [ruuter.core :as ruuter]))

(def routes [{:path "/"
              :method :get
              :response {:status 200
                         :body "Hi there!"}}])

(def request {:uri "/"
              :request-method :get})

(ruuter/route routes request) ; => {:status 200
                              ;     :body "Hi there!"}

This will attempt to match a route with the request map and return the matched route' response. If no route was found, it will attempt to find a route that has a :path that is :not-found, and return its response instead. But if not even that route was found, it will simply return a built-in 404 response instead.

Note that the request-method doesn't have to be a keyword, it can be anything that your HTTP server returns. But it does have to be called request-method for the router to know where to look for. That said, you do not have to provide neither method in the route, nor request-method in the request if you don't want to. You can skip both of them and let Ruuter route based on the :uri alone if you want.

Now, obviously on its own the router is not very useful as it needs an actual HTTP server to return the responses to the world, so here's an example that uses http-kit:

(ns myapp.core
  (:require [ruuter.core :as ruuter]
            [org.httpkit.server :as http]))

(def routes [{:path "/"
              :method :get
              :response {:status 200
                         :body "Hi there!"}}
             {:path "/hello/:who"
              :method :get
              :response (fn [req]
                          {:status 200
                           :body (str "Hello, " (:who (:params req)))})}])

(defn -main []
  (http/run-server #(ruuter/route routes %) {:port 8080}))

Ring Jetty set-up is almost identical to the one of http-kit, and looks like this:

(ns myapp.core
  (:require [ruuter.core :as ruuter]
            [ring.adapter.jetty :as jetty]))

(def routes [{:path "/"
              :method :get
              :response {:status 200
                         :body "Hi there!"}}
             {:path "/hello/:who"
              :method :get
              :response (fn [req]
                          {:status 200
                           :body (str "Hello, " (:who (:params req)))})}])

(defn -main []
  (jetty/run-jetty #(ruuter/route routes %) {:port 8080}))

You can also use Ruuter with Babashka, by using the built-in http-kit server, for example. Either add the dependency in your bb.edn file or if you want to make the whole thing one-file-rules-them-all, then load it in with deps/add-deps, like below:

#!/usr/bin/env bb

(deps/add-deps '{:deps {org.clojars.askonomm/ruuter {:mvn/version "1.3.4"}}})

(require '[org.httpkit.server :as http]
         '[babashka.deps :as deps]
         '[ruuter.core :as ruuter])

(def routes [{:path "/"
              :method :get
              :response {:status 200
                         :body "Hi there!"}}])

(http/run-server #(ruuter/route routes %) {:port 8082})

@(promise)

Like mentioned above, each route is a map inside a vector - the order is important only in that the route matcher will return the first result it finds according to :path.

Each route consists of three items:

A string path starting with a forward slash describing the URL path to match.

To create parameters from the path, prepend a colon (:) in front of a path slice like you would with a Clojure keyword.

A required parameter with a string such as /hi/:name, which would match any string that matches the \/hi\/.* regex in the URI, in its own slice. The :name itself will then be available with its value from the request passed to the response function, like this:

(fn [req]
  (let [name (:name (:params req))]
    {:status 200
     :body (str "Hi, " name)}))

A optional parameter with a string such as /hi/:name?, which would match any string that matches the \/hi\/?.*? regex in the URI, in its own slice. If there is a :name provided in the URI then it will then be available with its value from the request passed to the response function, like this:

(fn [req]
  (let [name (:name (:params req))]
    {:status 200
     :body (str "Hi, " name)}))

The above-mentioned :name and :name? only match in its own path slice, e.g inside a space surrounded by two forward slashes. They cannot, by design, match the whole URL path. If you need wildcard matching, instead use :name*, which will match everything, including forward slashes.

The HTTP method to listen for when matching the given path. This can be whatever the HTTP server uses. For example, if you're using http-kit for the HTTP server then the accepted values are:

• :get
• :post
• :put
• :delete
• :head
• :options
• :patch

The response can be a direct map, or a function returning a map. In case of a function, you will also get passed to you the request map that the HTTP server returns, with added-in :params that contain the values for the URL parameters you use in your route's :path.

Thus, a :response can be a map:

{:status 200
 :body "Hi there!"}

Or a function returning a map:

(fn [req]
  {:status 200
   :body "Hi there!"})

What the actual map can contain that you return depends again on the HTTP server you decided to use Ruuter with. The examples I've noted here are based on http-kit & ring jetty, but feel free to make a PR with additions for other HTTP servers.

• Fixes an issue where if used with middlewares (like Ring), or really anything that passes a :params key from outside of Ruuter in the request, Ruuter overwrites the :params key with its own parametarization. It now does a deep merge instead, with the outside parameters having priority. This means that Ruuter parameters will remain unless overwritten, and should co-exist with outside parameters nicely. Issue #6.

• Added and fixed some tests

• Removed ClojureScript from dependencies to make the bundle size smaller in case you want to use Ruuter with nbb.

• When using wildcard parameters, the keyword returned in ´:params´ of a request was ´:name*´, but aiming for consistency with an optional parameter where we remove the question mark ´?´, the asterisk has been removed.

• A small bugfix related to wildcard parameters losing the first character in the result.

• Fixed an issue with optional parameters not matching correctly when there were multiple optional paremeters in use.
• Implemented wildcard parameters in the form of :name*, which will match everything including forward slashes.

• Fixed an issue where CLJS compilation would fail because of the (:gen-class) that is JVM-only.

• Tests are now runnable for CLJS as well, via clojure -Atest.

• Fixed an issue with regex parsing. Sorry about that.

• Implemented optional route parameters, so now you can do paths like /hi/:name? in your routes, and it would match the route even if the :name is not present. All you have to do is add a question mark to the parameter, and that's it.

• Changed Ruuter from a .clj file to a .cljc file, so it would also work with ClojureScript. Although it would probably require a more hands-on set-up than just a drop-in to an HTTP server like http-kit or ring jetty, there is no reason that the router itself wouldn't work as it does not rely on any platform-specific code.

• Ruuter also works with Babashka, and I've created a "Setting up with Babashka" section in this README to show that.

• Made Ruuter server-agnostic, which means now it really is just a router and nothing else, and can thus be used with just about any HTTP server you can throw at it. It also means there are now zero dependencies! ZERO!