Re: Parse a field in JSON given a path to the field

[Andreas Röhler]

Am 11.11.21 um 19:42 schrieb Husain Alshehhi:
> Does emacs provide a function that can return a path from a JSON object? I find 
> something like this useful if I want a field from a nested, large JSON. Here is 
> an example of a JSON string
>
> ,----
> | {
> | "field" : {
> |   "field1" : {
> |     "field2" : {
> |       "field3" : "value"
> |     }
> |   }
> | }
> `----
>
> I do something like:
>
> ,----
> | ;; assume that the value is in json-string
> | (let ((json (json-parse json-string))
> |       (field (gethash "field" json))
> |       (field1 (gethash "field1" field))
> |       (field2 (gethash "field2" field1))
> |       (field3 (gethash "field3" field2)))
> |   ;; process field3
> |   )
> `----
>
> I wonder if there is something like
>
> ,----
> | (let ((field3 (json-parse-path "field/field1/field2/field3" json-string)))
> |   ;; process field3
> |   )
> `----

Maybe go on with this, which puts the value into messaging for now.

Idea is to specify the nesting in order to get the value of interest:


(defun getjsonfield (nesting)
  "Get the json-value of the provided nesting."
  (interactive "p")
  (while (< (nth 0 (parse-partial-sexp (point-min) (point))) nesting)
    (down-list))
  (when (looking-at "\\([[:blank:]]*\\)\\([[:print:]]+\\)")
    (goto-char (match-end 2))
    (skip-chars-forward " \t\r\n\f")
    (when (looking-at "\\([[:blank:]]*\\)\\([^: 
]+\\)[[:blank:]]*:[[:blank:]]*\\([[:print:]]+\\)")
      (message "%s" (match-string-no-properties 2))
      (message "%s" (match-string-no-properties 3)))))