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 <and...@tao11.riddles.org.uk>: > >>>>> "Charles" == Charles Cui <charles.cui1...@gmail.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) >
