Question

I have the following routes definition:

(require '[compojure.core :as ccore]
         '[ring.util.response :as response])

(def *main-routes*
     (ccore/defroutes avalanche-routes
       (ccore/GET "/" [] "Hello World 2")
       (ccore/GET "/images/:id" [id] (get-image-response id))))

In this example, requesting / works like a charm and returns the expected Hello World 2.

The get-images-response method is defined like this:

(defn get-image-response
  [id]
  (let [record (db/get-image id false)]
    (-> (response/response (:data record))
        (response/content-type (:content-type record))
        (response/header "Content-Length" (:size record)))))

I get a 404 though, so the serving of binary files doesn’t quite work yet. Any ideas why?

Edit:
Ok, the issue relates to the fact that images are being requested on /images/name.jpg. As soon as I remove the .jpg the handler gets called. So the question becomes how do I match on anything but the extension?

Answer 1

The real answer in this case was that there was a bug in the clojure-couchdb library. The patch is available on github here.

It boils down to adding the {:as :byte-array} map parameter and value to the request sent via clj-http to couch’s api.

The other issue in my code was that ring doesn’t really know what to do with byte-arrays when it’s rendering them. Rather than patching ring, I just wrapped the byte-array into a java.io.ByteArrayInputStream. Here is the complete code for handling the download:

(defn get-image-response
  [id]
  (let [record (db/get-image id false)]
    (-> (response/response (new java.io.ByteArrayInputStream (:data record)))
        (response/content-type (:content-type (:content-type record)))
        (response/header "Content-Length" (:size record)))))