ok, great. This is really fabulous. So far most everything feels
natural and good.
I see something odd in terms of the jsonb use case coverage. One of
the major headaches with json deserialization presently is that
there's no easy way to easily move a complex (record- or array-
containing) json structure into a row object. For example,
create table bar(a int, b int[]);
postgres=# select jsonb_populate_record(null::bar, '{"a": 1, "b":
[1,2]}'::jsonb, false);
ERROR: cannot populate with a nested object unless use_json_as_text
is true
If find the use_json_as_text argument here to be pretty useless
(unlike in the json_build to_record variants where it least provides
some hope for an escape hatch) for handling this since it will just
continue to fail:
postgres=# select jsonb_populate_record(null::bar, '{"a": 1, "b":
[1,2]}'::jsonb, true);
ERROR: missing "]" in array dimensions
OTOH, the nested hstore handles this no questions asked:
postgres=# select * from populate_record(null::bar, '"a"=>1,
"b"=>{1,2}'::hstore);
a | b
---+-------
1 | {1,2}
So, if you need to convert a complex json to a row type, the only
effective way to do that is like this:
postgres=# select* from populate_record(null::bar, '{"a": 1, "b":
[1,2]}'::json::hstore);
a | b
---+-------
1 | {1,2}
Not a big deal really. But it makes me wonder (now that we have the
internal capability of properly mapping to a record) why *both* the
json/jsonb populate record variants shouldn't point to what the nested
hstore behavior is when the 'as_text' flag is false. That would
demolish the error and remove the dependency on hstore in order to do
effective rowtype mapping. In an ideal world the json_build
'to_record' variants would behave similarly I think although there's
no existing hstore analog so I'm assuming it's a non-trival amount of
work.
Now, if we're agreed on that, I then also wonder if the 'as_text'
argument needs to exist at all for the populate functions except for
backwards compatibility on the json side (not jsonb). For non-complex
structures it does best effort casting anyways so the flag is moot.
