Bypass the JSON object using PL / SQL, and output all data in key value format in Oracle

If you have access to the native JSON types (JSON_ELEMENT_T, JSON_ARRAY_T, etc.) you should always use them over using the APEX_JSON package ans they will have much better performance. A package similar to the one below can be used to output the full hierarchy of a JSON object or array. Feel free to tweak the package to change the format of the output.

Package Specification

CREATE OR REPLACE PACKAGE output_json
AS
    c_padding_char     CONSTANT VARCHAR2 (1) := '-';
    c_padding_amount   CONSTANT PLS_INTEGER := 1;

    PROCEDURE output_scalar (p_element    json_element_t,
                             p_padding    PLS_INTEGER,
                             p_json_key   VARCHAR2 DEFAULT NULL);

    PROCEDURE output_object (p_object json_object_t, p_padding PLS_INTEGER);

    PROCEDURE output_array (p_array json_array_t, p_padding PLS_INTEGER);

    PROCEDURE output_element (p_element    json_element_t,
                              p_padding    PLS_INTEGER,
                              p_json_key   VARCHAR2 DEFAULT NULL);
END;
/

Package Body

CREATE OR REPLACE PACKAGE BODY output_json
AS
    PROCEDURE output_scalar (p_element    json_element_t,
                             p_padding    PLS_INTEGER,
                             p_json_key   VARCHAR2 DEFAULT NULL)
    IS
    BEGIN
        DBMS_OUTPUT.put_line (
               LPAD (c_padding_char, p_padding, c_padding_char)
            || CASE WHEN p_json_key IS NOT NULL THEN p_json_key || ' : ' END
            || CASE
                   WHEN p_element.is_boolean
                   THEN
                       CASE WHEN p_element.to_boolean THEN 'TRUE' ELSE 'FALSE' END || ' (boolean)'
                   WHEN p_element.is_date
                   THEN
                       TO_CHAR (p_element.TO_DATE, 'YYYY-MM-DD') || ' (date)'
                   WHEN p_element.is_number
                   THEN
                       p_element.TO_NUMBER || ' (number)'
                   WHEN p_element.is_string
                   THEN
                       p_element.TO_STRING || ' (string)'
               END);
    END;

    PROCEDURE output_object (p_object json_object_t, p_padding PLS_INTEGER)
    IS
        l_keys      json_key_list;
        l_element   json_element_t;
    BEGIN
        l_keys := p_object.get_keys;

        FOR i IN 1 .. l_keys.COUNT
        LOOP
            l_element := p_object.get (l_keys (i));
            output_element (l_element, p_padding, l_keys (i));
        END LOOP;
    END;

    PROCEDURE output_array (p_array json_array_t, p_padding PLS_INTEGER)
    IS
    BEGIN
        FOR i IN 0 .. p_array.get_size - 1
        LOOP
            output_element (p_array.get (i), p_padding);
        END LOOP;
    END;

    PROCEDURE output_element (p_element    json_element_t,
                              p_padding    PLS_INTEGER,
                              p_json_key   VARCHAR2 DEFAULT NULL)
    IS
    BEGIN
        DBMS_OUTPUT.put_line (
            CASE
                WHEN p_json_key IS NOT NULL AND NOT p_element.is_scalar THEN p_json_key || ' : '
            END);

        IF p_element.is_scalar
        THEN
            output_scalar (p_element, p_padding, p_json_key);
        ELSIF p_element.is_object
        THEN
            output_object (TREAT (p_element AS json_object_t), p_padding + c_padding_amount);
        ELSIF p_element.is_array
        THEN
            output_array (TREAT (p_element AS json_array_t), p_padding + c_padding_amount);
        END IF;
    END;
END;
/

Example Call

DECLARE
    l_clob   CLOB;
BEGIN
    l_clob :=
        '{"arr":[1,2,3],"devices":{"id":"d652f632-0835-871b-a140-58701f019000","scale_id":"88348A32BD3D149FE055000000000001"},"data":{"external_id":"40023"},"data_weight":{"weight":"20322","prevWeight":"1000","prevTransaction":"1607680754361","transaction":"1607680754361","on":"false","transactionDataCount":"1","stable":"false","duration":"12","transactionMaxWeight":"2000","perimetr":"true","driverInCar":"false"}}';

    output_json.output_element (json_element_t.parse (l_clob), 0);
END;
/

Example Output

arr :
--1 (number)
--2 (number)
--3 (number)
devices :
--id : "d652f632-0835-871b-a140-58701f019000" (string)
--scale_id : "88348A32BD3D149FE055000000000001" (string)
data :
--external_id : "40023" (string)
data_weight :
--weight : "20322" (string)
--prevWeight : "1000" (string)
--prevTransaction : "1607680754361" (string)
--transaction : "1607680754361" (string)
--on : "false" (string)
--transactionDataCount : "1" (string)
--stable : "false" (string)
--duration : "12" (string)
--transactionMaxWeight : "2000" (string)
--perimetr : "true" (string)
--driverInCar : "false" (string)