Re: BUG #14354: Wrong interpretation of JSON 'null'

On 10/5/16, kouber@gmail.com <kouber@gmail.com> wrote:
> The following bug has been logged on the website:
>
> Bug reference:      14354
> Logged by:          Kouber Saparev
> Email address:      kouber@gmail.com
> PostgreSQL version: 9.4.5
> Operating system:   Fedora
> Description:
>
> Trying to pass 'null' to jsonb_each_text() results in an ERROR, while at the
> same time it is considered a valid JSON value. This behaviour seems quite
> inconsistent - either such a value should be considered invalid in general,
> either the function should treat it as a normal NULL instead.
>
> db=# select 'null'::jsonb;
>  jsonb
> -------
>  null
> (1 row)
>
> db=# select jsonb_each_text('null'::jsonb);
> ERROR:  cannot call jsonb_each_text on a non-object
>
> db=# select jsonb_each_text(NULL);
>  jsonb_each_text
> -----------------
> (0 rows)

It is not a bug. It works as expected.

1. NULL::jsonb is not the same as 'null'::jsonb
PG's NULL (not jsonb's 'null'!) as input returns NULL output.

2. Argument for jsonb_each_text should be a jsonb with an
_json-object_ at top-level (see types of primitives by [1] and [2]),
e.g. '{"key1":"value1", "key2":"value2"}' to produce pairs (key,
value).

Your example has jsonb value with a null-value at top-level. The same
exception is raised if you send a json-string as an input:
db=# select jsonb_each_text('"str"'::jsonb);
ERROR:  cannot call jsonb_each_text on a non-object


P.S.: what you're expecting from the "select
jsonb_each_text('null'::jsonb)" call?

[1] https://www.postgresql.org/docs/9.6/static/datatype-json.html#JSON-TYPE-MAPPING-TABLE
[2] https://www.postgresql.org/docs/9.6/static/datatype-json.html#JSON-KEYS-ELEMENTS
--
Best regards,
Vitaly Burovoy