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request.el

README.rst

Request.el -- Easy HTTP request for Emacs Lisp

Links

What is it?

Request.el is a HTTP request library with multiple backends. It supports url.el which is shipped with Emacs and curl command line program. User can use curl when s/he has it, as curl is more reliable than url.el. Library author can use request.el to avoid imposing external dependencies such as curl to users while giving richer experience for users who have curl.

As request.el is implemented in extensible manner, it is possible to implement other backend such as wget. Also, if future version of Emacs support linking with libcurl, it is possible to implement a backend using it. Libraries using request.el automatically can use these backend without modifying their code.

Request.el also patches url.el dynamically, to fix bugs in url.el. See `monkey patches for url.el`_ for the bugs fixed by request.el.

Installation

request.el is available on MELPA and MELPA stable.

You can install request.el by package.el

Examples

GET:

(request
 "http://httpbin.org/get"
 :params '(("key" . "value") ("key2" . "value2"))
 :parser 'json-read
 :success (cl-function
           (lambda (&key data &allow-other-keys)
             (message "I sent: %S" (assoc-default 'args data)))))

POST:

(request
 "http://httpbin.org/post"
 :type "POST"
 :data '(("key" . "value") ("key2" . "value2"))
 ;; :data "key=value&key2=value2"  ; this is equivalent
 :parser 'json-read
 :success (cl-function
           (lambda (&key data &allow-other-keys)
             (message "I sent: %S" (assoc-default 'form data)))))

POST file (WARNING: it will send the contents of the current buffer!):

(request
 "http://httpbin.org/post"
 :type "POST"
 :files `(("current buffer" . ,(current-buffer))
          ("data" . ("data.csv" :data "1,2,3\n4,5,6\n")))
 :parser 'json-read
 :success (cl-function
           (lambda (&key data &allow-other-keys)
             (message "I sent: %S" (assoc-default 'files data)))))

Rich callback dispatch (like jQuery.ajax):

(request
 "http://httpbin.org/status/418"     ; try other codes, for example:
 ;; "http://httpbin.org/status/200"  ; success callback will be called.
 ;; "http://httpbin.org/status/400"  ; you will see "Got 400."
 :parser 'buffer-string
 :success
 (cl-function (lambda (&key data &allow-other-keys)
                (when data
                  (with-current-buffer (get-buffer-create "*request demo*")
                    (erase-buffer)
                    (insert data)
                    (pop-to-buffer (current-buffer))))))
 :error
 (cl-function (lambda (&rest args &key error-thrown &allow-other-keys)
                (message "Got error: %S" error-thrown)))
 :complete (lambda (&rest _) (message "Finished!"))
 :status-code '((400 . (lambda (&rest _) (message "Got 400.")))
                (418 . (lambda (&rest _) (message "Got 418.")))))

Flexible PARSER option:

(request
 "https://github.com/tkf/emacs-request/commits/master.atom"
 ;; Parse XML in response body:
 :parser (lambda () (libxml-parse-xml-region (point) (point-max)))
 :success (cl-function
           (lambda (&key data &allow-other-keys)
             ;; Just don't look at this function....
             (let ((get (lambda (node &rest names)
                          (if names
                              (apply get
                                     (first (xml-get-children
                                             node (car names)))
                                     (cdr names))
                            (first (xml-node-children node))))))
               (message "Latest commit: %s (by %s)"
                        (funcall get data 'entry 'title)
                        (funcall get data 'entry 'author 'name))))))

PUT JSON data:

(request
 "http://httpbin.org/put"
 :type "PUT"
 :data (json-encode '(("key" . "value") ("key2" . "value2")))
 :headers '(("Content-Type" . "application/json"))
 :parser 'json-read
 :success (cl-function
           (lambda (&key data &allow-other-keys)
             (message "I sent: %S" (assoc-default 'json data)))))

Another PUT JSON example (nested JSON using alist structure, how to represent a boolean & how to selectively evaluate lisp):

;; (1) Prepend alist structure with a backtick (`) rather than single quote (')
;;     to allow elisp evaluation of selected elements prefixed with a comma (,)
;; (2) This value is expected as a boolean so use the nil / t elisp alist denotation
;; (3) The function will be evaluated as it has been prefixed with a comma (,)
(request
 "http://httpbin.org/put"
 :type "PUT"
 :data (json-encode `(("jsonArray" . (("item1" . "value 1") ;; (1)
                                      ("item2" . t)         ;; (2)
                                      ("item3" . ,(your-custom-elisp-function)))))) ;; (3)
 :headers '(("Content-Type" . "application/json"))
 :parser 'json-read
 :success (cl-function
           (lambda (&key data &allow-other-keys)
             (message "I sent: %S" (assoc-default 'json data)))))

GET with Unix domain socket data:

(request
 "http:/hello.txt"
 :unix-socket "/tmp/app.sock"
 :parser (lambda () (buffer-string))
 :success (cl-function
           (lambda (&key data &allow-other-keys)
             (message "Got: %s" data))))

Compatibility / backends

Supported Emacs versions:

Emacs version Does request.el work? Tested on Travis CI Build Status
GNU Emacs 25.1 yes (as of this writing) yes
GNU Emacs 24.5 yes (as of this writing) yes
GNU Emacs 24.4 yes (as of this writing) yes

Supported backends:

Backends Remarks Multipart Form Automatic Decompression Unix Socket
url.el Included in Emacs      
curl Reliable

Related projects

leathekd/grapnel · GitHub:
"HTTP request for Emacs lib built on curl with flexible callback dispatch"
cinsk/emacs-curl · GitHub:
"CURL wrapper for Emacs"
furl-el - Google Project Hosting:
"A wrapper for url.el that adds a nicer API and the ability to make multipart POST requests."

License

Request.el is free software under GPL v3. See COPYING file for details.