Reading data in an inner array with pljson - pljson

Question

Sample JSON:
{"TestResults": [{
"Messages": ["PASS: Status date 7/1/2002, ID"],
"Status": "Pass",
"Name": "IFTA License"
},
{
"Messages": ["Carrier compliant"],
"Status": "Pass",
"Name": "MCOLS carrier compliance check"
},
{
"Messages": ["No"],
"Status": "Pass",
"Name": "IFTA Revoked"
},
{
"Messages": ["PASS=> Not under Federal Out Of Service order"],
"Status": "Pass",
"Name": "Federal Out of Service Status"
},
{
"Messages": ["PASS => Carrier status code 100: Active ID"],
"Status": "Pass",
"Name": "IRP Status"
},
{
"Messages": ["PASS => Status Code 1: Active"],
"Status": "Pass",
"Name": "IFTA Status"
},
{
"Messages": ["PASS => UCR fee paid for 2017",
"PASS => UCR fee paid for 2016"],
"Status": "Pass",
"Name": "UCR Fee Status"
},
{
"Messages": ["PASS => MCMIS Status = A: Active"],
"Status": "Pass",
"Name": "USDOT Status"
},
{
"Messages": ["PASS=> Not under Federal Out Of Service order"],
"Status": "Pass",
"Name": "PRISM Target Status"
},
{
"Messages": ["PASS => ISS Score: 42 No Inspection Warranted"],
"Status": "Pass",
"Name": "ISS2 Score"
},
{
"Messages": ["PASS => MCS-150 Up to Date: Last Update 4/28/2016"],
"Status": "Pass",
"Name": "MCS-150 Status"
},
{
"Messages": ["PASS => Carrier is authorized"],
"Status": "Pass",
"Name": "Operating Authority Status"
}]
}
Code utilizing pljson:
DECLARE
l_http_req UTL_HTTP.REQ;
l_http_resp UTL_HTTP.RESP;
l_response CLOB;
l_buffer VARCHAR2(4000);
l_response_json common.json;
l_testresults_list common.json_list;
l_messages_list common.json_list;
BEGIN
utl_http.set_wallet('file:/home/oracle/wallet/blah',NULL);
l_http_req := utl_http.begin_request('https://some_url', 'GET');
utl_http.set_header(l_http_req, 'Content-Type', 'application/json');
utl_http.set_authentication(l_http_req, 'user', 'password');
BEGIN
dbms_lob.createtemporary(l_response, TRUE);
dbms_lob.open(l_response, dbms_lob.lob_readwrite);
l_http_resp := utl_http.get_response(l_http_req);
LOOP
utl_http.read_text(l_http_resp, l_buffer, 2000);
dbms_lob.writeappend(l_response, LENGTH(l_buffer), l_buffer);
END LOOP;
EXCEPTION
WHEN utl_http.end_of_body THEN
NULL;
WHEN OTHERS THEN
RAISE;
END;
dbms_lob.close(l_response);
utl_http.end_response(l_http_resp);
-- Convert CLOB content to JSON object.
BEGIN
l_response_json := common.json(l_response);
EXCEPTION
WHEN OTHERS THEN
RAISE;
END;
BEGIN
l_testresults_list := json_ext.get_json_list(l_response_json, 'TestResults');
FOR i IN 1..l_testresults_list.COUNT LOOP
dbms_output.put_line('name: '||common.json_ext.get_string(common.json(l_testresults_list.GET(i)), 'Name'));
dbms_output.put_line('status: '||common.json_ext.get_string(common.json(l_testresults_list.GET(i)), 'Status'));
l_messages_list := json_ext.get_json_list(common.json(l_testresults_list.GET(i)), 'Messages');
FOR j IN 1..l_messages_list.COUNT LOOP
dbms_output.put_line('messages: '||common.json_ext.get_string(common.json(l_messages_list.GET(j)), 'Messages'));
dbms_output.put_line('count : '||j);
END LOOP;
END LOOP;
END;
EXCEPTION
WHEN OTHERS THEN
utl_http.end_response(l_http_resp);
RAISE;
END;
I'm able to extract the name and status values from this JSON, but when this line of code is executed to extract the messages:
dbms_output.put_line('messages: '||common.json_ext.get_string(common.json(l_messages_list.GET(j)), 'Messages'));
I receive an ORA-30625: method dispatch on NULL SELF argument is disallowed
Has anyone been able to successfully read values from an inner array with pljson?

Answer 1

Since you are working with the array, you should be able to simply:
dbms_output.put_line( l_messages_list.get(j).to_char() );