### Update
This expression will evaluate to show the cause. The only requirement is an emacs with `url`. As you can see, the result from using `curl` and that from using the `url` package is different. Fields `upvoted`, `downvoted`, and `body_markdown` are missing from the `url` request. What is differing between these two requests, and how can I fix the problem?
I recommend instrumenting the function before evaluating it.
Since this issue is bordering off-topic now, I'm going to post [this question on Emacs.SE][emacs.se]. The underlying issue though still concerns the API. I believe these two issues have the same cause, but if I should post this as a separate question for tracking purposes, just let me know.
<!-- language: lang-lisp -->
(defconst access-token
"YOUR ACCESS TOKEN")
(defconst key
"AN API 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")
(args
(mapconcat
#'identity
`(,(format "access_token=%s"
(replace-regexp-in-string
"%" "%%" (url-hexify-string access-token)))
,(format "key=%s"
(replace-regexp-in-string
"%" "%%" (url-hexify-string key)))
"site=meta"
"pagesize=100"
"filter=%%21GoYr1we0U5inG5G7wBg4JBGpbgX%%29C7LDqpy-%%2AbfwPOujOr4SR4W%%29bLNSyYUpQDdTwTj.XChTFB0gfLaAJq0hv"
"body=this-is-an-answer-test-for-sx.el--%s")
"&")))
(if use-curl
(shell-command-to-string
(format
"curl --silent -X POST --data %S %s | gunzip"
(format args random-body-2)
method))
(let ((url-automatic-caching t)
(url-inhibit-uncompression t)
(url-request-data (format args random-body-1))
(url-request-method "post")
(url-request-extra-headers
'(("Content-Type" . "application/x-www-form-urlencoded"))))
(with-current-buffer
(url-retrieve-synchronously method)
(goto-char (point-min))
(search-forward "\n\n")
(delete-region (point-min) (point))
(buffer-string))))))
(tmp:api-bug t access-token key)
"{\"items\":[{\"owner\":{\"reputation\":160,\"display_name\":\"Sean Allred\"},\"downvoted\":false,\"upvoted\":false,\"score\":0,\"last_activity_date\":1421684370,\"creation_date\":1421684370,\"answer_id\":247295,\"share_link\":\"http://meta.stackexchange.com/a/247295/188148\",\"body_markdown\":\"this-is-an-answer-test-for-sx.el--e3eeb6228ed9c2c58e5385b73493f0f0\",\"link\":\"http://meta.stackexchange.com/questions/3122//247295#247295\"}],\"has_more\":false,\"quota_max\":10000,\"quota_remaining\":9979,\"page\":1,\"page_size\":100,\"total\":1}"
(tmp:api-bug nil access-token key)
"{\"items\":[{\"owner\":{\"reputation\":160,\"display_name\":\"Sean Allred\"},\"score\":0,\"last_activity_date\":1421684555,\"creation_date\":1421684555,\"answer_id\":247297,\"share_link\":\"http://meta.stackexchange.com/a/247297/188148\",\"link\":\"http://meta.stackexchange.com/questions/3122//247297#247297\"}],\"has_more\":false,\"quota_max\":10000,\"quota_remaining\":9977,\"page\":1,\"page_size\":100,\"total\":1}"
---
When upvoting an answer via the API, `preview=true` gives the correct new `score` value but `preview=false` does not.
When the following expressions are evaluated, we receive different responses.
<!-- language: lang-lisp -->
(sx-method-call "answers"
:id 7192
:submethod "upvote"
:auth 'warn
:url-method 'post
:keywords (list (cons 'preview 'true)) ;; NOTE
:site "emacs")
=>
[((question_id . 7189)
(answer_id . 7192)
(creation_date . 1420761994)
(last_edit_date . 1420762419)
(last_activity_date . 1420762419)
(score . 4)
(is_accepted . t)
(owner
(link . "http://emacs.stackexchange.com/users/105/drew")
(display_name . "Drew")
(profile_image . "https://www.gravatar.com/avatar/32a8e553d85d193ee5ae1533ce6ec158?s=128&d=identicon&r=PG&f=1")
(user_type . "registered")
(user_id . 105)
(reputation . 6689)))]
versus
<!-- language: lang-lisp -->
(sx-method-call "answers"
:id 7192
:submethod "upvote"
:auth 'warn
:url-method 'post
:keywords (list (cons 'preview 'false)) ;; NOTE
:site "emacs")
=>
[((question_id . 7189)
(answer_id . 7192)
(creation_date . 1420761994)
(last_edit_date . 1420762419)
(last_activity_date . 1420762419)
(score . 3)
(is_accepted . t)
(owner
(link . "http://emacs.stackexchange.com/users/105/drew")
(display_name . "Drew")
(profile_image . "https://www.gravatar.com/avatar/32a8e553d85d193ee5ae1533ce6ec158?s=128&d=identicon&r=PG&f=1")
(user_type . "registered")
(user_id . 105)
(reputation . 6689)))]
Note the difference:
- when `preview=true`, `.score=4`
- when `preview=false`, `.score=3`
However, the POST does succeed; `.score` is updated when you re-retrieve the answer:
<!-- language: lang-lisp -->
(sx-method-call "answers"
:id 7192
:site "emacs")
=>
[((question_id . 7189)
(answer_id . 7192)
(creation_date . 1420761994)
(last_edit_date . 1420762419)
(last_activity_date . 1420762419)
(score . 4)
(is_accepted . t)
(owner
(link . "http://emacs.stackexchange.com/users/105/drew")
(display_name . "Drew")
(profile_image . "https://www.gravatar.com/avatar/32a8e553d85d193ee5ae1533ce6ec158?s=128&d=identicon&r=PG&f=1")
(user_type . "registered")
(user_id . 105)
(reputation . 6699)))]
Note that to reproduce the issue with the Elisp examples provided, you must `sx-authenticate` first.
----------
I cannot figure out how to correctly `POST` to the API with curl, so feel free to edit this Q to use curl if you know how. As it stands, clone http://stackapps.com/q/3950/11299 (or install `M-x package-install RET sx RET` from MELPA) and require `sx-load`.
<sub>Cross-reference [`vermiculus/sx.el#223`][pull223], [Emacs.SE question][emacs.se]</sub>
[pull223]: https://github.com/vermiculus/sx.el/pull/223
[emacs.se]: http://emacs.stackexchange.com/q/7545/2264