Re: how to correctly cast json value to text?

[Pavel Stehule]

po 3. 5. 2021 v 11:26 odesílatel Marko Tiikkaja  napsal:

> On Mon, May 3, 2021 at 12:24 PM Pavel Stehule 
> wrote:
>
>> Is it possible to do this with built functionality?
>>
>> I miss the cast function for json scalar string value to string.
>>
>
> #>>'{}'
>

It is working. Thank you. But this syntax is a little bit scary.  Maybe we
can introduce some functions for this case. Until to pg 14 this
functionality was not necessary, but now it can be nice to have it.

DO $$
DECLARE v jsonb;
BEGIN
  -- hodnota musi byt validni json
  v['a'] = '"Ahoj"';
  RAISE NOTICE '%', v['a'] #>> '{}';
END;
$$;
NOTICE:  Ahoj
DO

Some ideas about the name of this function?

CREATE OR REPLACE FUNCTION jsonscalar_to_text(jsonb)
RETURNS text AS $$
SELECT $1 #>> '{}'
$$ LANGUAGE sql;



>
> .m
>

Re: how to correctly cast json value to text?

[Marko Tiikkaja]

On Mon, May 3, 2021 at 12:24 PM Pavel Stehule 
wrote:

> Is it possible to do this with built functionality?
>
> I miss the cast function for json scalar string value to string.
>

#>>'{}'


.m

Re: how to correctly cast json value to text?

[Pavel Stehule]

Hi

po 3. 5. 2021 v 11:15 odesílatel Pavel Stehule 
napsal:

> Hi
>
> I am testing a new subscripting interface for jsonb, and I found one issue.
>
> DO $$
> DECLARE v jsonb;
> BEGIN
>   v['a'] = '"Ahoj"';
>   RAISE NOTICE '%', v['a'];
> END;
> $$;
> NOTICE:  "Ahoj"
> DO
>
> When I use this interface for reading, the jsonb type is returned. What is
> the correct way for casting from jsonb text to text value? I would not
> double quotes inside the result. Cast to text doesn't help. For operator
> API we can use "->>" symbol. But we have nothing similar for subscript API.
>

now I need function like

CREATE OR REPLACE FUNCTION public.value_to_text(jsonb)
 RETURNS text
 LANGUAGE plpgsql
 IMMUTABLE
AS $function$
DECLARE x jsonb;
BEGIN
  x['x'] = $1;
  RETURN x->>'x';
END;
$function$

DO $$
DECLARE v jsonb;
BEGIN
  -- hodnota musi byt validni json
  v['a'] = '"Ahoj"';
  RAISE NOTICE '%', value_to_text(v['a']);
END;
$$;
NOTICE:  Ahoj
DO

Is it possible to do this with built functionality?

I miss the cast function for json scalar string value to string.

Regards

Pavel


> Regards
>
> Pavel
>
>
>

how to correctly cast json value to text?

[Pavel Stehule]

Hi

I am testing a new subscripting interface for jsonb, and I found one issue.

DO $$
DECLARE v jsonb;
BEGIN
  v['a'] = '"Ahoj"';
  RAISE NOTICE '%', v['a'];
END;
$$;
NOTICE:  "Ahoj"
DO

When I use this interface for reading, the jsonb type is returned. What is
the correct way for casting from jsonb text to text value? I would not
double quotes inside the result. Cast to text doesn't help. For operator
API we can use "->>" symbol. But we have nothing similar for subscript API.

Regards

Pavel