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

[Tim Landscheidt]

Husain Alshehhi <husain@alshehhi.io> wrote:

> 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
> |   )
> `----

If the path is fixed, you could also use let-alist:

| ELISP> (let ((json (json-parse-string "{\n  \"field\": {\n    \"field1\": {\n 
     \"field2\": {\n        \"field3\": \"value\"\n      }\n    }\n  }\n}\n"
|                                       :object-type 'alist)))
|          (let-alist json
|            (message "field/field1/field2/field3 = %S" 
.field.field1.field2.field3)))
| "field/field1/field2/field3 = \"value\""
| ELISP>

Tim