return-json-from-compojure

(ns web01.core
  (:import
        java.util.Map
        java.util.HashMap
        [java.io File InputStream]
        [clojure.lang IDeref IFn ISeq])
  (:use
        compojure.core,
        ring.adapter.jetty
        clojure.contrib.json.read
        clojure.contrib.json.write )
    (:require
        [compojure.response :as response]
        [compojure.route :as route] ))

;---------------------------------------
; for testing, switch between text and json
;---------------------------------------
(def json-header {"Content-Type" "application/json"})
(def text-header {"Content-Type" "text/html"} )
; for debugging
(def header text-header)

;---------------------------------------
; define a java.util.HashMap
;---------------------------------------
(def hashmap
  (let [
    body (HashMap.)
    hmap (HashMap.)]
    (doto body
      (.put "a" 1)
      (.put "b" 2)
      (.put "c" 3))
    (doto hmap
      (.put :body body))
    hmap))
;---------------------------------------
; TODO: define a java Array
;---------------------------------------
(def an-array (to-array ["one" "two" "three"]))

;---------------------------------------
; overrides
;---------------------------------------
(defmethod response/render String [_ html]
  {:status  200 :headers header :body  (json-str html)})

(defmethod response/render ISeq [_ coll]
  {:status 200, :headers header, :body (json-str coll)})

(defmethod response/render Map [_ m]
  (merge
    {:status 200, :headers header, :body ""}
    m
    {:body (json-str (:body m ""))}))

; added method to process 'an-array', which is passed as a java.lang.Object
(defmethod response/render Object [_ o]
  {:status 200, :headers header, :body (json-str o)})

(defroutes main-routes
  ; handled by the 'response/render String method
  (GET "/jsonarray" [] (json-str [1,2,3]))

  ; clojure *and* java maps need to be wrapped in a :body, as the 'render Map' method is preferred in response/render
  ; multi-method...and I cannot seem to override this
  (GET "/map" [] {:body {"a" 1, "b" 2, "c", 3}})
  (GET "/hashmap" [] hashmap)

  ; array is passed as a java.lang.Object
  (GET "/array" [] an-array)

  ; I'm not sure why the vector isn't recognized by the 'response/render ISeq' method...
  (GET "/vector" []  [1,2,3])

  ; handled by the 'response/render ISeq' method
  (GET "/list" []  (list 1 2 3))

  ; 404 the request
  (GET "/404" [] {:status 404 :headers header :body {"data" "nothing"}})
    (route/not-found "<h1>Page not found</h1>"))