Re: Extract numeric filed in JSONB more effectively

po 14. 8. 2023 v 9:06 odesílatel Andy Fan <zhihui(dot)fan1213(at)gmail(dot)com> napsal:

>
>> We'd still have functions like jsonb_field_as_numeric() under the
>> hood, but there's not an expectation that users call them explicitly.
>>
>
> To avoid the lots of functions like jsonb_field_as_int2/int4, I defined
> Datum jsonb_object_field_type(.., Oid target_oid) at last, so the
> function must return "internal" or "anyelement". Then we can see:
>
> select jsonb_object_field_type(tb.a, 'a'::text, 1700) from tb;
> ERROR: cannot display a value of type anyelement.
>

you cannot to use type as parameter. There should be some typed value - like

jsonb_object_field, '{"a":10}', 'a', NULL::int)

and return type should be anyelement.

Another solution should be more deeper change like implementation of
"coalesce"

>
> The reason is clear to me, but I'm not sure how to fix that or deserves
> a fix? Or shall I define jsonb_object_field_int2/int8 to avoid this?
>
> This is an unresolved issue at the latest patch.
> --
> Best Regards
> Andy Fan
>