A simple way to generate ring handlers




A simple library for defining ring handlers, a more flexible & powerful version of 'defpage' from Noir. It is an alternative to compojure's


Clojars Project

(:require [defpage.core :as defpage :refer (defpage)])

(defpage foo "/foo/bar" [request]
  "hello world")

the defpage macro takes an optional route name, the route path, then the standard arguments and function body. It defn's a function of one argument, a ring request.

The route path can also be a vector, to specify which HTTP methods it responds to:

(defpage [:post "/bar"] [request]
  "successful post")

Regexes can also be specified

(defpage ping-user [:post "/user/:id/ping" {:id #"\d+"}] ...)

The full grammar is: (defpage Name? Route fn-binding body)

Route = String | [Request-Method Route-Path Route-Regex?] ; Request-Method = Keyword ; Request-Path = String ;

defpage uses compojure and clout under the hood, so all standard compojure/clout route syntax works. route params are available to the function in the request object.

(defpage user [:get  "/user/:id" {:id #"\d+"}] [req]
  (let [uid (-> req :params :id)]

defpage is mostly stateless, in that defining a page doesn't automatically make it serve pages. The macro just creates a normal defn with extra metadata. To hook up your new routes to ring, use collect-routes:


collect-routes collects all defpages in a single namespace, and returns a handler function that behaves like a compojure handler: a fn that takes a request, and returns a ring response, or nil if no route matched. Called with no arguments, it collects routes in the current namespace. defpages are ordered according to line number (from the :line metadata) in the namespace.

Route ordering between namespaces can be handled using standard ring/compojure techniques:

(defn handler []
    (collect-routes* 'foo)
    (collect-routes* 'bar)))


defpages and collect routes both return simple fns that take ring request and return ring responses (or nil), so testing is easy. You can pass a ring request to a defpage fn, or the result of collect-routes:

(defpage foo [req]
  {:status 200
   :body "hello world"})

(deftest foo-works
  (is (= 200 (foo {:uri "/foo" :request-method :get}))))


If you'd like to apply a middleware to routes, but you don't want to interfere with route handling, use map-wrap-routes. For a motivating example, let's say you want to require login for a set of routes, but you want non-matching routes to 404:

(defn catch-all [request]
  {:status 404
   :body nil})

(defpage "/foo" [req]
(defpage "/bar" [req]

(defn wrap-require-login [handler]
  (fn [request]
    (if (logged-in? request)
      (handler request)
      {:status 403
       :body "login required"})))

(def logged-in-app
  (->> (defpage/find-defpages (find-ns 'authenticated.ns))
       (defpage/map-wrap-matching-routes wrap-require-login)

(defn whole-app []
 (routes #'logged-in-app

This will properly check for logged in on "/foo" and "/bar", and return 404 on "/bogus"

Data model

routes defined by defpage are just standard defns with extra metadata:

{:defpage.core/defpage true
 :defpage.core/method :get
 :defpage.core/route "/foo/bar"}

You can use url-for to return a complete path, given a route

(url-for ping-user {:id 10}) => "/user/10/ping"


0.1.4 - map-wrap-routes now updates the request :params to contain the route params from the matching route. Also updates the request to includ :defpage.core/method and :defpage.core/route of the matching route.


Copyright © 2015 Allen Rohner.

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.