APEX_JSON get array object - oracle

Question

declare
l_json_doc VARCHAR2(32767);
l_numcols number;
l_numrows number;
begin
l_json_doc := '{
"table": {
"name": "sometablename",
"numofcolumns": 5,
"numofrows": 5,
"colheadings": [{
"colname": "customcol1",
"coltype": "number"
},
{
"colname": "customcol2",
"coltype": "varchar2"
},
{
"colname": "customcol3",
"coltype": "varchar2"
},
{
"colname": "customcol4",
"coltype": "varchar2"
},
{
"colname": "customcol5",
"coltype": "number"
}
],
"data": [{
"customcol1": "datacolumn1",
"customcol2": "datacolumn2",
"customcol3": "datacolumn3",
"customcol4": "datacolumn4",
"customcol5": "datacolumn5"
},
{
"customcol1": "2datacolumn1",
"customcol2": "2datacolumn2",
"customcol3": "2datacolumn3",
"customcol4": "2datacolumn4",
"customcol5": "2datacolumn5"
},
{
"customcol1": "3datacolumn1",
"customcol2": "3datacolumn2",
"customcol3": "3datacolumn3",
"customcol4": "3datacolumn4",
"customcol5": "3datacolumn5"
},
{
"customcol1": "4datacolumn1",
"customcol2": "4datacolumn2",
"customcol3": "4datacolumn3",
"customcol4": "4datacolumn4",
"customcol5": "4datacolumn5"
}
]
}
}';
APEX_JSON.parse(l_json_doc);
l_numcols := APEX_JSON.get_count(p_path => 'table.colheadings');
l_numrows := APEX_JSON.get_count(p_path => 'table.data');
FOR i IN 1 .. l_numrows LOOP
FOR j IN 1 .. l_numcols LOOP
dbms_output.put_line('TEST ' || APEX_JSON.get_varchar2(p_path => 'table.data[%d]') );
END LOOP;
END LOOP;
end;
This is my code which is supposed to extract the data array objects. I expect the following output:
TEST {"customcol1": "datacolumn1","customcol2": "datacolumn2","customcol3": "datacolumn3","customcol4": "datacolumn4","customcol5": "datacolumn5"}
TEST { "customcol1": "2datacolumn1","customcol2": "2datacolumn2","customcol3": "2datacolumn3","customcol4": "2datacolumn4","customcol5": "2datacolumn5"}
etc ...
But when I try to get the json object from the data array using the APEX_JSON.get_varchar2 it returns empty

Answer 1

Two problems with the code there
You have not provided an index to the get_varchar2 function. So the path is not complete. You need to provide a value in the p0 parameter of that function
That's not how APEX_JSON.get_varchar2 works. You are expecting the
function to return the entire JSON object in the data array but get_varchar2 cannot do that. It can only get you the VALUE that is a VARCHAR at a specified path. It cannot get you the entire object.
For your output
DECLARE
l_json_doc VARCHAR2 (32767);
l_numcols NUMBER;
l_numrows NUMBER;
v_colname VARCHAR2 (32767);
BEGIN
l_json_doc := '{
"table": {
"name": "sometablename",
"numofcolumns": 5,
"numofrows": 5,
"colheadings": [{
"colname": "customcol1",
"coltype": "number"
},
{
"colname": "customcol2",
"coltype": "varchar2"
},
{
"colname": "customcol3",
"coltype": "varchar2"
},
{
"colname": "customcol4",
"coltype": "varchar2"
},
{
"colname": "customcol5",
"coltype": "number"
}
],
"data": [{
"customcol1": "datacolumn1",
"customcol2": "datacolumn2",
"customcol3": "datacolumn3",
"customcol4": "datacolumn4",
"customcol5": "datacolumn5"
},
{
"customcol1": "2datacolumn1",
"customcol2": "2datacolumn2",
"customcol3": "2datacolumn3",
"customcol4": "2datacolumn4",
"customcol5": "2datacolumn5"
},
{
"customcol1": "3datacolumn1",
"customcol2": "3datacolumn2",
"customcol3": "3datacolumn3",
"customcol4": "3datacolumn4",
"customcol5": "3datacolumn5"
},
{
"customcol1": "4datacolumn1",
"customcol2": "4datacolumn2",
"customcol3": "4datacolumn3",
"customcol4": "4datacolumn4",
"customcol5": "4datacolumn5"
}
]
}
}';
APEX_JSON.parse (l_json_doc);
l_numcols := APEX_JSON.get_count (p_path => 'table.colheadings');
l_numrows := APEX_JSON.get_count (p_path => 'table.data');
FOR i IN 1 .. l_numrows
LOOP
DBMS_OUTPUT.put ('TEST {');
FOR j IN 1 .. l_numcols
LOOP
v_colname :=
apex_json.get_varchar2 ('table.colheadings[%d].colname', j);
DBMS_OUTPUT.put (
'"' || v_colname || '":"'
|| APEX_JSON.get_varchar2 (
p_path => 'table.data[%d].' || v_colname,
p0 => i)
|| '",');
END LOOP;
DBMS_OUTPUT.put_line ('}');
END LOOP;
END;
Here is the output of the code:
TEST {"customcol1":"datacolumn1","customcol2":"datacolumn2","customcol3":"datacolumn3","customcol4":"datacolumn4","customcol5":"datacolumn5",}
TEST {"customcol1":"2datacolumn1","customcol2":"2datacolumn2","customcol3":"2datacolumn3","customcol4":"2datacolumn4","customcol5":"2datacolumn5",}
TEST {"customcol1":"3datacolumn1","customcol2":"3datacolumn2","customcol3":"3datacolumn3","customcol4":"3datacolumn4","customcol5":"3datacolumn5",}
TEST {"customcol1":"4datacolumn1","customcol2":"4datacolumn2","customcol3":"4datacolumn3","customcol4":"4datacolumn4","customcol5":"4datacolumn5",}
NOTE: I didn't care to remove the final comma after the last key:value pair in each row. If you want that then you have to store all the key value pairs in a variable and RTRIM the comma out.