bug#8706: 24.0.50; [PATCH] Function to build a URL query-string

[Ted Zlatanov]

On Fri, 20 May 2011 11:37:45 -0700 Ian Eure <ian@simplegeo.com> wrote: 

IE> This patch adds a url-build-query-string method, which performs the
IE> opposite job of url-parse-query-string. I find myself needing this
IE> method in many projects, and having it in url-util.el seems
IE> beneficial.

I think this is useful.

IE> +  (c-concat-separated
IE> +   (mapcar (lambda (pair) (apply 'format "%s=%s" pair)) query) "&"))

I would use `mapconcat' (it's what `c-concat-separated' uses under the
hood anyhow).

Also `format' errors out if it doesn't have enough arguments and it's
legitimate to build a URL query like "url?x;y;z" where x, y, and z don't
have values.  So I would change the lambda to (untested):

(lambda (pair)
  (if (nth 1 pair)
      (apply 'format "%s=%s" pair)
    (format "%s" (car-safe pair))))

This also handles the case where `pair' is nil by design or by accident.

Finally, the key and the value should be URL-encoded.  Do you assume
that will be done before the function is called?

Thanks
Ted