Reitit routing library

Reitit routing for client and server-side routing

Supports use of ring specification and middleware

Provides content negotiation and data validation.

Library Dependency

Include the bundled distribution containing all modules

Clojure CLILeiningen

deps.edn

metosin/reitit {:mvn/version "0.7.0-alpha5"}

[metosin/reitit "0.7.0-alpha5"]

Require namespace

Require the reitit.ring namespace to provide routing and ring specification support.

ProjectREPL

(:require 
 [reitit.ring :as ring])

(require '[reitit.ring :as ring])

Router function

Takes all requests and delegates them to handler functions

Routes are defined as a vector of vectors structure, with each nested vector containing a string key defining unique paths that match a specific request.

Each key has a configuration map to define a handler for a specific HTTP method (:get :ost etc.)

(def router
  (ring/ring-handler
   (ring/router
    [["/" {:get welcome}]]
    ["/status" {:get status}])))

Passing system configuration argument

Component systems (donut, integrant) use a system configuration (hash-map) which is passed to the router component during start up.

Define the router as a function to recieve the system configuration as an argument and make it available in part or full to the handler functions.

(defn app
  [system-config]
  (ring/ring-handler
   (ring/router
    [["/api"
      ["/v1"
       (scoreboard/routes system-config)]]]

    ;; - middleware, coersion & content negotiation
    router-configuration)))

Handler functions

Handler functions are Clojure functions that take a request map.

(defn welcome [_]
  {:status 200 :body "Awesome Reitit Ring"})

constantly function is commonly used for handlers that do not use the request data initially. constantly returns an anonymous function that takes the ring request hash-map.

(def status
  (constantly 
    (ring.util.response/response 
     {:application "practicalli awesome-api Service" :status "Alive"})))

Use _ argument name when request not used

Handlers might not use the data in a request to return a response. By convention the _ character is used for the argument name when the request data is not used.

System Status handler

An example status report handler namespace

(ns practicalli.awesome-api.api.system-admin
  "Gameboard API system administration handlers"
  (:require [ring.util.response :refer [response]]))

(def status
  "Service status report for external monitoring services, e.g. Statuscake
  Return:
  - `constantly` returns an anonymous function that returns a ring response hash-map"
  (constantly (response {:application "practicalli awesome-api Service" :status "Alive"})))