15/11/2017

Accessing JSON data in elisp

:PUBDATE: <2017-11-15 mer 10:50> :ID: 339a61c5-ffab-4b55-a334-35ffddc39bde

<2017-11-14 mar>

(require 'json)  

(let* ((json-object-type 'hash-table)  
       (json-array-type 'list)  
       (json-key-type 'string)  
       (json (json-read-file "test.json")))  
  (car (gethash "projects" json)))

The let* is required because otherwise the call to json-read-file will not see the previously bound values as let sets them in parallel…

As for the access functions, gethash retrieves a value by key from a hash table, whereas car returns the first list element. If you need a different one, you can use nth with an index.

https://emacs.stackexchange.com/questions/27407/accessing-json-data-in-elisp

Introducing json.el zero

<2017-11-14 mar> JSON is a lightweight data interchange format based on a subset of JavaScript. You can read all about JSON at json.org. json.el is a JSON parser and generator for Emacs Lisp, which can produce an Emacs Lisp data structure from a JSON object and vice-versa. It’s been Included with Emacs since February 2008.

Using it is pretty straightforward; here are some examples.

TODO org-json.el — conversion between org and json zero

https://www.emacswiki.org/emacs/org-json.el

;; Usage:

;; 1. call (org-json-encode) to convert org(in current buffer) to json,
;;    return convert json.
;; 2. call (org-json-decode json) to convert json to org,
;;    return converted text.

;; Example:

;; * i1 [2,3,4]
;; * i2 3.4
;; * i3 "fdsafs"
;; => (("i1" . [2,3,4]) ("i2" . 3.4) ("i3" . "fdsafs"))
;;

;; * i1
;; [2,3,4]
;; * i2
;; 3.4
;; => (("i1"  . [2,3,4]) ("i2" 3.4)).

;; * lv1_1
;; ** lv2a 1
;; ** lv2b 2
;; * lv1_2 "tt"
;; => (("lv1_1" . (("lv2a" . 1) ("lv2b" . 2))) ("lv1_2" . "tt"))

;; * vect
;; ** 0 "idx0"
;; ** 1 1.23
;; ** 2
;; [5.2, "2.3t", 1]
;; => (("vect" . ["idx0" 1.23 [5.2 "2.3t" 1]]))

;; * long_src
;; +begin_src
;; line1
;; line2
;; +end_src
;; => (("long_src" . "line1\nline2\n"))

(<)

Accessing JSON data in elisp

Introducing json.el zero

TODO org-json.el — conversion between org and json zero