What libraries or functions, internal or external, does Elisp use to
extract fields from JSON?
reddit / emacs

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vfclists · 2022-12-21 23:07

Does Emacs have good libraries for extracting fields from JSON values?

Are there some libraries which demonstrate good working examples of
these?

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phr46 · 2022-12-21 23:35

Emacs comes with a JSON parsing library:

[Parsing JSON](https://www.gnu.org/software/emacs/manual/html_node/eli
sp/Parsing-JSON.html)

I don't know a good place for examples but to start you off, json-
parse-string parses JSON from a string into an elisp hash table, which
you can access with gethash:

    (gethash "hello" (json-parse-string "{\"hello\": \"world\"}"))
    -> "world"

[Hash Access](https://www.gnu.org/software/emacs/manual/html_node/elis
p/Hash-Access.html)

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sebhoagie · 2022-12-22 00:34

You can also change the type of object you get back from hash-table to
alist, and then use the wonderful get-alist macro the navigate the
file contents.
This is good for smaller JSON, the bigger what you are parsing the
more you benefit from the faster hash-tables.

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vfclists · 2022-12-24 13:05

I have had a go at this and it is all good.