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clojureleiningencompojurering

trying to use ring.middleware.json-params with compojure

I am new to Clojure, leiningen, and java tool chains (but not to lisp, functional programming, software in general). I'm trying to bootstrap some RESTful web services in Compojure.

I had no trouble getting started with compojure, following the instructions at

https://github.com/weavejester/compojure/wiki/Getting-Started

I am now trying to incrementally add in functionality from the now-outdated web site

http://mmcgrana.github.com/2010/08/clojure-rest-api.html

Starting with the working leiningen project from the first link above (it works via lein ring start, I add ONE line to project.clj

(defproject hello-world "0.1.0-SNAPSHOT"
  :description "FIXME: write description"
  :url "http://example.com/FIXME"
  :dependencies [[org.clojure/clojure "1.4.0"]
                 [ring-json-params "0.1.3"]  ;;; <---===/// Here's the line I added
                 [compojure "1.1.5"]]
  :plugins [[lein-ring "0.8.2"]]
  :ring {:handler hello-world.handler/app}
  :profiles
  {:dev {:dependencies [[ring-mock "0.1.3"]]}})

Then I rerun lein deps and a bunch of stuff downloads. All good, the project still works. Now I add one line to handler.clj:

(ns hello-world.handler
  (:use     compojure.core)
  (:use     ring.middleware.json-params)  ;;; <---===/// Here's the line I added
  (:require [compojure.handler :as handler]
            [compojure.route :as route]))

(defroutes app-routes
  (GET "/" [] "Hello World")
  (route/not-found "Not Found"))

(def app
  (handler/site app-routes))

And now I get

java.io.FileNotFoundException: Could not locate ring/middleware/json_params__init.class or ring/middleware/json_params.clj on classpath: 
 at clojure.lang.RT.load (RT.java:432)
    clojure.lang.RT.load (RT.java:400)
    clojure.core$load$fn__4890.invoke (core.clj:5415)
    clojure.core$load.doInvoke (core.clj:5414)

Since I am a total noob to the toolchain, I don't know how to set or inspect the classpath or to find out where json_params was deposited by leiningen, or even how to look inside the class files to find out what the name should have been.

In addition to a specific solution to this problem, I would appreciate pointers to newbie stuff so maybe I can solve straightforward problems like this on my own in the future.

Solution

  • Did you get that error when you start the server? Nothing is wrong on my enviroment. enter image description here

    Here's what i have done:

    lein new compojure hello

    Then change project.clj as you do and run:

    lein deps

    At last add:

    (:use ring.middleware.json-params)

    to handle.clj

    Start server, no error occurs.

    I suggest you building a new project and try again.