How can I "URL decode" a string in Emacs Lisp?

Question

I've got a string like "foo%20bar" and I want "foo bar" out of it.

I know there's got to be a built-in function to decode a URL-encoded string (query string) in Emacs Lisp, but for the life of me I can't find it today, either in my lisp/ folder or with Google.

What is it called?

score 49 · Answer 1 · answered Mar 05 '09 at 08:06

49

url-unhex-string

answered Mar 05 '09 at 08:06

huaiyuan

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I've got a url-unhex-string no match with Emacs 25 :/ – Natim Jan 22 '19 at 10:49
2

You may need to (require 'url-util) -- in practice, this will often be done by some other code loading but certainly not good to rely on that. – Derek Slager May 12 '20 at 17:07

score 30 · Answer 2 · answered Jun 30 '11 at 21:03

In my case I needed to do this interactively. The previous answers gave me the right functions to call, then it was just a matter of wrapping it a little to make them interactive:

(defun func-region (start end func)
  "run a function over the region between START and END in current buffer."
  (save-excursion
    (let ((text (delete-and-extract-region start end)))
      (insert (funcall func text)))))

(defun hex-region (start end)
  "urlencode the region between START and END in current buffer."
  (interactive "r")
  (func-region start end #'url-hexify-string))

(defun unhex-region (start end)
  "de-urlencode the region between START and END in current buffer."
  (interactive "r")
  (func-region start end #'url-unhex-string))

Add salt, I mean bind to keys according to taste.

score 11 · Answer 3 · edited Jul 31 '21 at 08:07

Emacs is shipped with a URL library that provides a bunch of URL parsing functions—as huaiyuan and Charlie Martin already pointed out. Here is a small example that'd give you an idea how to use it:

(let ((url "http://www.google.hu/search?q=elisp+decode+url&btnG=Google+keres%E9s&meta="))
  ;; Return list of arguments and values
  (url-parse-query-string
   ;; Decode hexas
   (url-unhex-string
    ;; Retrieve argument list
    (url-filename
     ;; Parse URL, return a struct
     (url-generic-parse-url url)))))
=> (("meta" "") ("btnG" "Google+keresés") ("/search?q" "elisp+decode+url"))

I think is better to rely on it rather than Org-mode as it is its main purpose to parse a URL.

score 6 · Accepted Answer · answered Mar 04 '09 at 20:31

6

org-link-unescape does the job for very simple cases ... w3m-url-decode-string is better, but it isn't built in and the version I have locally isn't working with Emacs 23.

answered Mar 04 '09 at 20:31

Derek Slager

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That's good enough for now. It is strange that it uses only a constant list of 17 chars, though. Maybe I'll fix that sometime. – Ken Mar 04 '09 at 21:07
15

`url-unhex-string` does what you want. – Cheeso May 12 '11 at 12:22

score 2 · Answer 5 · edited Jul 31 '21 at 08:03

2

You can grab urlenc from MELPA and use urlenc:decode-region for a region or urlenc:decode-insert to insert your text interactively.

edited Jul 31 '21 at 08:03

Peter Mortensen

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answered May 24 '21 at 11:32

elig

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score 0 · Answer 6 · answered Mar 04 '09 at 18:44

0

I think you're making it a little too hard: split-string will probably do most of what you want. For fancier stuff, have a look at the functions in url-expand.el; unfortunately, many of them don't have doc-strings, so you may have to read code.

url-generic-parse-url looks like a potential winner.

answered Mar 04 '09 at 18:44

Charlie Martin

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Hmm, maybe I misspoke. I've got a string like "foo%20bar" and I want "foo bar" out of it. I don't see how split-string or url-generic-parse-url or anything in url-expand.el really helps here. – Ken Mar 04 '09 at 19:07

How can I "URL decode" a string in Emacs Lisp?

6 Answers6

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