Re: json results parsing

Thanks you guys for answering my questions, and sorry for confusion.
To clarify, I think my question is functions like json_each or
json_object_keys() are
set returning functions (
https://www.postgresql.org/docs/9.5/static/functions-srf.html)
which means it returns a set of results into a Datum.
I am wondering how to parse the Datum? I know there are functions like
DatumGetCString()
which parse the Datum into a cstring. Are there any helpers for set
returning functions?

2018-05-30 23:00 GMT-07:00 Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>:

> >>>>> "Charles" == Charles Cui <charles(dot)cui1984(at)gmail(dot)com> writes:
>
> Charles> Hi mentors and hackers,
> Charles> Found the json API page here
> Charles> https://www.postgresql.org/docs/9.3/static/functions-json.html
>
> Charles> For some APIs, it returns set of results, for example,
> Charles> json_each(json) and json_object_keys().
>
> Charles> Basically, I want to call these json API inside a plugin,
>
> If you want to process the whole of a json (not jsonb) value inside a
> plugin, then maybe pg_parse_json is what you should be looking at rather
> than the SQL-callable functions.
>
> For jsonb, there's an iterator interface (JsonbIteratorInit/
> JsonbIteratorNext)
>
> --
> Andrew (irc:RhodiumToad)
>