This is for sx.el, a StackExchange client for Emacs. I'm trying to determine whether this issue is a bug in url or a bug in StackExchange's API. If you need the API key, please get in touch with either myself or @Malabarba – we're on the Gitter chatroom for the project pretty regularly.

The following form evaluates to two different responses depending on whether curl is used or whether the url package is used. Since API requests are time-sensitive (and to cut down on your time investment), I've included the responses I get for the two (as parsed by json-read-from-string for readability's sake).

(defconst tmp:access-token

(defconst tmp:key

(defun tmp:api-bug (use-curl access-token key)
  "Post a test answer to the formatting sandbox."
  (let ((random-body-1 (md5 (current-time-string)))
        (random-body-2 (md5 (md5 (current-time-string))))
        (method "https://api.stackexchange.com/2.2/questions/3122/answers/add")
          `(,(format "access_token=%s"
                      "%" "%%" (url-hexify-string access-token)))
            ,(format "key=%s"
                      "%" "%%" (url-hexify-string key)))

    (if use-curl
          "curl --silent -X POST --data %S %s | gunzip"
          (format args random-body-2)
      (let ((url-automatic-caching t)
              (url-inhibit-uncompression t)
              (url-request-data (format args random-body-1))
              (url-request-method "post")
               '(("Content-Type" . "application/x-www-form-urlencoded"))))
              (url-retrieve-synchronously method)
            (goto-char (point-min))
            (search-forward "\n\n")
            (delete-region (point-min) (point))

(require 'json)

(json-read-from-string (tmp:api-bug t tmp:access-token tmp:key))
((total . 1)
 (page_size . 100)
 (page . 1)
 (quota_remaining . 9979)
 (quota_max . 10000)
 (has_more . :json-false)
 (items .
        [((link . "http://meta.stackexchange.com/questions/3122//247295#247295")
          (body_markdown . "this-is-an-answer-test-for-sx.el--e3eeb6228ed9c2c58e5385b73493f0f0")
          (share_link . "http://meta.stackexchange.com/a/247295/188148")
          (answer_id . 247295)
          (creation_date . 1421684370)
          (last_activity_date . 1421684370)
          (score . 0)
          (upvoted . :json-false)
          (downvoted . :json-false)
           (display_name . "Sean Allred")
           (reputation . 160)))]))

(json-read-from-string (tmp:api-bug nil tmp:access-token tmp:key))
((total . 1)
 (page_size . 100)
 (page . 1)
 (quota_remaining . 9977)
 (quota_max . 10000)
 (has_more . :json-false)
 (items .
        [((link . "http://meta.stackexchange.com/questions/3122//247297#247297")
          (share_link . "http://meta.stackexchange.com/a/247297/188148")
          (answer_id . 247297)
          (creation_date . 1421684555)
          (last_activity_date . 1421684555)
          (score . 0)
           (display_name . "Sean Allred")
           (reputation . 160)))]))

Cross-reference: https://stackapps.com/q/6083/11299

  • 3
    Could this be related to user-agent or cookies?
    – abo-abo
    Commented Jan 19, 2015 at 16:47
  • @abo-abo I'm unfortunately unfamiliar with most web stuff. I've very much hacked this together (with a lot of help from @Jonathan), so I'm still learning about all this stuff. There is no mention of user agent in the variables given by url. Commented Jan 19, 2015 at 16:48
  • 3
    I'm not a pro either, but I know that websites can give different responses, depending on user-agent. Most tools can spoof it. And url-retrieve has a inhibit-cookies option, so at least in some cases this could be relevant.
    – abo-abo
    Commented Jan 19, 2015 at 16:50
  • @abo-abo I just tried, and the cookies option makes no difference.
    – Malabarba
    Commented Jan 20, 2015 at 16:55
  • Did you try url-user-agent and useragentstring.com/pages/curl
    – abo-abo
    Commented Jan 20, 2015 at 17:03

1 Answer 1


Annoyingly, the problem was here: (url-request-method "post").

Changing that to (url-request-method "POST") fixes everything.

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