JSON operator feature request

[david . turon]

Good morning,

we have everywhere in code:
 COALESCE(json_data, '{}'::json(b)) || json(b)_build_object(...)
        or something like
IF json_data IS NULL THEN ....


I made some code refactoring with

CREATE OR REPLACE FUNCTION public.jsonb_concat_null(a jsonb, b jsonb)
RETURNS jsonb AS
$$

    SELECT
    CASE
            WHEN a IS NOT NULL AND b IS NOT NULL
                THEN a || b
            WHEN a IS NULL AND b IS NULL
                THEN NULL
            WHEN a IS NULL
                THEN b
            WHEN b IS NULL
                THEN a
            ELSE
                NULL

    END;

$$ LANGUAGE SQL IMMUTABLE;


CREATE OPERATOR public.||| (
    PROCEDURE = public.jsonb_concat_null,
    LEFTARG = JSONB,
    RIGHTARG = JSONB,
    COMMUTATOR =  OPERATOR(public.|||)
);


So now is possible join json data with NULL:

json_data || NULL -> NULL
json_data ||| NULL -> json_data

without coalesce or other NOT NULL check in code. Maybe can be usefull have
this operator in pg? Code can be written better than my and in C. Anybody
have same issue with concat json and NULL?

David T.
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