Postgres json alias - sql

Question

I write SQL-query in PostgreSQL. I have now:
SELECT T.order,
(SELECT row_to_json(item) FROM (
SELECT T.title, T.subtitle, T.text
FROM table T
WHERE T.id = 1
) AS item)
FROM table T
WHERE T.id = 1;
The result is:
order | row_to_json
---------------+------------------------------------------------------
2 | {"title":"AAA","subtitle":"aaaa","text":"aaaa"}
But I need result:
order | row_to_json
---------------+------------------------------------------------------
2 | {"item":{"title":"AAA","subtitle":"aaaa","text":"aaaa"}}
Could you tell me how I can get it?

Answer 1

You wouldn't need subquery for such result and using Postgres jsonb function jsonb_build_object you can achieve your goal like that:
-- Test data:
WITH "table"( id, "order", title, subtitle, "text" ) AS (
VALUES ( 1::int, 2::int, 'AAA'::text, 'aaaa'::text, 'aaaa'::text),
( 2::int, 3::int, 'BBB'::text, 'bbbb'::text, 'bbbb'::text)
)
-- The query:
SELECT "order",
jsonb_build_object(
'items',
jsonb_build_object(
'title', title,
'subtitle', subtitle,
'text', "text"
)
) AS myjson
FROM "table"
WHERE id = 1;
-- Result:
order | myjson
-------+-----------------------------------------------------------------
2 | {"items": {"text": "aaaa", "title": "AAA", "subtitle": "aaaa"}}
(1 row)