Oracle JSON output group by key - sql

Question

I generate SQL statements dynamically from the input file and I want to have the output in JSON format grouped by a key which I provide in an alias in the select statement.
The input file comes from another system and it looks like this:
'abc' AS [x.test1],
'cde' AS [y.test2],
'fgh' AS [y.test3]
In SQL Server I have a working query like this:
SELECT
(SELECT
'abc' AS [x.test1],
'cde' AS [y.test2],
'fgh' AS [y.test3]
FROM "dbo"."TEST"
FOR JSON PATH,
WITHOUT_ARRAY_WRAPPER
) AS RESULT
It returns this output which is grouped by key and this is working perfectly:
{"x":{"test1":"abc"},"y":{"test2":"cde","test3":"fgh"}}
I want to achieve the same output with oracle.
Currently, I got to here:
SELECT
(
SELECT json_object(
KEY '[x.test1]' IS 'abc',
KEY '[y.test2]' IS 'cde',
KEY '[y.test3]' IS 'fgh'
)
FROM test
)
AS RESULT from DUAL;
Problem is that this doesn't group my output by the key:
{"[x.test1]":"abc","[y.test2]":"cde","[y.test3]":"fgh"}

Answer 1

You could nest json_object() calls:
SELECT json_object(
KEY 'x' IS json_object(
KEY 'test1' IS 'abc'
),
KEY 'y' IS json_object(
KEY 'test2' IS 'cde',
KEY 'test3' IS 'fgh'
)
)
AS RESULT from DUAL;
RESULT
{"x":{"test1":"abc"},"y":{"test2":"cde","test3":"fgh"}}
fiddle
Or as you refer to grouping, if your data is really coming from tables, you could use json_objectagg() and the table data, with something like:
select json_object(
'x' value json_object(x.j_key value x.j_value),
'y' value json_objectagg(y.j_key, y.j_value)
) as result
from x
left join y on y.id = x.id
group by x.id, x.j_key, x.j_value
RESULT
{"x":{"test1":"abc"},"y":{"test2":"cde","test3":"fgh"}}
fiddle

Answer 2

WITH data (expr) AS (
SELECT q'~'abc' AS [x.test1],'cde' AS [y.test2],'fgh' AS [y.test3]~' FROM DUAL
),
rdata(expr) AS (
SELECT regexp_substr(expr,'[^,]+',1,LEVEL) AS expr
FROM data
CONNECT BY regexp_substr(expr,'[^,]+',1,LEVEL) IS NOT NULL
),
exprs AS (
SELECT expr, regexp_substr(expr, q'~'(.*)'~', 1, 1, 'i', 1) as val,
regexp_substr(expr, q'~\[(.*)\]~', 1, 1, 'i', 1) as path
FROM rdata
),
spaths AS (
SELECT e.*, LEVEL as lvl, regexp_substr(path,'[^\.]+',1,LEVEL) as pitem
FROM exprs e
CONNECT BY regexp_substr(path,'[^\.]+',1,LEVEL) IS NOT NULL AND prior val = val AND PRIOR sys_guid() IS NOT NULL
)
SELECT json_object(
s.pitem VALUE json_objectagg(
p.pitem VALUE p.val
)
) AS js
FROM spaths s
JOIN spaths p ON s.val = p.val AND p.lvl = 2
WHERE s.lvl = 1
GROUP BY s.pitem
;
JS
{"x":{"test1":"abc"}}
{"y":{"test2":"cde","test3":"fgh"}}