Clojure, Compojure-api: Access Request headers

Question

I am trying to implement request end point authentication. For that I want to access accessToken value from request headers.

My GET request end Point is

CURL Command

curl -X GET \
  'http://localhost:3000/hello?id=10' \
  -H 'accesskey: 23423sfsdfsdfsfg' \
  -H 'cache-control: no-cache' \
  -H 'content-type: application/json' \
  -H 'postman-token: f69b34e6-4888-ec31-5fbc-b734e176571b' \
  -d '{
    "artwork": {id" : 1}
}'

HTTP Command

GET /hello?id=10 HTTP/1.1
Host: localhost:3000
Content-Type: application/json
accessKey: 23423sfsdfsdfsfg
Cache-Control: no-cache
Postman-Token: b974719d-5e1d-4d68-e910-e9ca50562b2f

My Code for GET Method Implementation

(defapi app
  (GET ["/hello/:id", :id #"[0-9]+" ] [id]
    (log/info "Function begins from here")
    (def artworkData (logic/artwork-id (->> id (re-find #"\d+") Long/parseLong)))
    (def data (if (not-empty artworkData)
               {:data artworkData :status 200}
               {:data [] :status 201}))
   (ok data)))

I want to fetch accessKey: 23423sfsdfsdfsfg from request header.

Is there any way to get the value and use in my GET Method?

I am using POSTMAN to test all API end points.

Answer 1

Compojure has custom destructuring syntax (i.e., different from Clojure proper) for the parameters. You can bind the whole request map using keyword :as

(defapi app
  (GET ["/hello/:id", :id #"[0-9]+" ] [id :as request]

If you want only request headers, the following should work

(defapi app
  (GET ["/hello/:id", :id #"[0-9]+" ] [id :as {:headers headers}]

Note that this still allows you to bind path parameter id.

Answer 2

The Compojure Sweet API functions like [compojure.api.sweet :refer [defroutes GET PUT context]] let us bind the whole request or bind select headers. In the snippet below [:as request] makes the whole request available to me.

  (GET
    "/download/:id"
    [:as request]
    :header-params [{x-http-request-id :- X-Http-Request-Id nil}]
    :path-params [id :- (describe String "The encoded id of the image")]
    :summary "Download the image bytes"
    :description "This endpoint responds 307 - Temporary Redirect to a cacheable presigned S3 URL for the actual bytes."
    (let [http-response (->> request
                             walk/keywordize-keys
                             util/extract-base-url
                             (transform/generate-resource-url (util/decode-key id))
                             status/temporary-redirect)
          expire-time (-> 3 hours from-now coerce/to-date ring-time/format-date)]
      (log/infof "x-http-request-id is %s" x-http-request-id)
      (response/header http-response "Expires" expire-time)))

1. The vector beginning :header-params [{x-http-request-id :- X-Http-Request-Id nil}] makes the value of the "X-HTTP-REQUEST-ID" header in the request available to my function directly as x-http-request-id.
2. The squiglies thing {...} makes the presence of x-http-request-id header optional in the request.
3. The :- X-Http-Request-Id nil stuff gives it a Schema which is defined somewhere else like (s/defschema X-Http-Request-Id (rss/describe String "Request ID for tracing calls")).

Once you've got those kids bound to names you just work with the names. The compojure folks don't do a great job at documenting everything you can do there. Poke around their examples and you'll find stuff like this.