Create JSON from XML - JSON_AGG OUTPUT PROBLEM - sql

Question

I have a problem with converting XML content to JSON format (with plain oracle select statement), where more then 1 sub level of data is present in the original XML - with my code the result of level 2+ is presented as string and not as JSON_OBJECT. Please, could someone tell me, where is fault in my code or what I'm doing wrong:
source:
<envelope>
<sender>
<name>IZS</name>
<country>SU</country>
<address>LOCATION 10B</address>
<address>1000 CITY</address>
<sender_identifier>SU46794093</sender_identifier>
<sender_address>
<sender_agent>SKWWSI20XXX</sender_agent>
<sender_mailbox>SI56031098765414228</sender_mailbox>
</sender_address>
</sender>
</envelope>
transformation select statement:
WITH SAMPLE AS (SELECT XMLTYPE ('
<envelope>
<sender>
<name>IZS</name>
<country>SU</country>
<address>LOCATION 10B</address>
<address>1000 CITY</address>
<sender_identifier>SU46794093</sender_identifier>
<sender_address>
<sender_agent>SKWWSI20XXX</sender_agent>
<sender_mailbox>SI56031098765414228</sender_mailbox>
</sender_address>
</sender>
</envelope>') XMLDOC FROM DUAL)
SELECT JSON_SERIALIZE (
JSON_OBJECT (
KEY 'envelope' VALUE
JSON_OBJECTAGG (
KEY ID_LEVEL1 VALUE
CASE ID_LEVEL1
WHEN 'sender' THEN
( SELECT JSON_OBJECTAGG (
KEY ID_LEVEL2 VALUE
CASE ID_LEVEL2
WHEN 'sender_address' THEN
( SELECT JSON_OBJECTagg (KEY ID_LEVEL22 VALUE TEXT_LEVEL22)
FROM XMLTABLE ('/sender/sender_address/*'
PASSING XML_LEVEL2
COLUMNS ID_LEVEL22 VARCHAR2 (128) PATH './name()',
TEXT_LEVEL22 VARCHAR2 (128) PATH './text()'
)
)
ELSE
TEXT_LEVEL2
END)
FROM XMLTABLE ('/sender/*'
PASSING XML_LEVEL2
COLUMNS ID_LEVEL2 VARCHAR2 (1024) PATH './name()',
TEXT_LEVEL2 VARCHAR2 (1024) PATH './text()'
)
)
ELSE
'"' || TEXT_LEVEL1 || '"'
END FORMAT JSON)
) PRETTY
)JSON_DOC
FROM SAMPLE, XMLTABLE ('/envelope/*'
PASSING XMLDOC
COLUMNS ID_LEVEL1 VARCHAR2 (1024) PATH './name()',
TEXT_LEVEL1 VARCHAR2 (1024) PATH './text()',
XML_LEVEL2 XMLTYPE PATH '.'
);
wrong result:
{
"envelope" :
{
"sender" :
{
"name" : "IZS",
"country" : "SU",
"address" : "LOCATION 10B",
"address" : "1000 CITY",
"sender_identifier" : "SU46794093",
"sender_address" : "{\"sender_agent\":\"SKWWSI20XXX\",\"sender_mailbox\":\"SI56031098765414228\"}"
}
}
}
wrong part:
***"sender_address" : "{\"sender_agent\":\"SKWWSI20XXX\",\"sender_mailbox\":\"SI56031098765414228\"}"***

Answer 1

For the level 1 text you're wrapping the value in double-quotes and specifying format json; you aren't doing that for level 2. If you change:
ELSE
TEXT_LEVEL2
END
to:
ELSE
'"' || TEXT_LEVEL2 || '"'
END FORMAT JSON)
then the result is:
{
  "envelope" :
  {
    "sender" :
    {
      "name" : "IZS",
      "country" : "SU",
      "address" : "LOCATION 10B",
      "address" : "1000 CITY",
      "sender_identifier" : "SU46794093",
      "sender_address" :
      {
        "sender_agent" : "SKWWSI20XXX",
        "sender_mailbox" : "SI56031098765414228"
      }
    }
  }
}
fiddle

Answer 2

The problem is that you need kind of conditional "FORMAT JSON" in the "SELECT JSON_OBJECTAGG ( KEY ID_LEVEL2 VALUECASE ID_LEVEL2": when the ID_LEVEL2 is 'sender_address' but not in the ELSE part, but the syntax requires you put after the END of CASE, and of course this fails for the "ELSE TEXT_LEVEL2" part.