Oracle Reading from json respond - sql

Question

i have the next problem. Having this query:
select apex_web_service.make_rest_request(
p_url => 'https://something.com/rest/Discount'
,p_http_method => 'GET'
,p_username => 'username'
,p_password => 'password'
) as custom
from dual;
That return this:
{"hasMore":false,"items":[{"id":12,"Origin":"ALL","Part":"PO423S","Channel":"RC"},{"id":13,"Origin":"ALL","Part":"LO123D","Channel":"RC"},{"id":14,"Origin":"ALL","Part":"SD765S","Channel":"AP"}]}
I want to make a Channel group by to see how many Channels i have to insert into another table.
i try this just to list:
select d.custom.items
from (
select apex_web_service.make_rest_request(
p_url => 'https://something.com/rest/Discount'
,p_http_method => 'GET'
,p_username => 'username'
,p_password => 'password'
) as custom
from dual) d;
but i have this error:
ORA-22806: no es un objeto ni un elemento REF
22806. 00000 - "not an object or REF"
*Cause: An attempt was made to extract an attribute from an item that is
neither an object nor a REF.
*Action: Use an object type or REF type item and retry the operation.
Error en la línea: 12, columna: 8
I also test the next:
create table temp_json (
json_data blob not null
);
alter table temp_json
add constraint temp_data_json
check ( json_data is json );
insert into temp_json
select apex_web_service.make_rest_request(
p_url => 'https://something.com/rest/Discount'
,p_http_method => 'GET'
,p_username => 'username'
,p_password => 'password
) as customDiscAplicability
from dual
;
select d.json_data.items
from temp_json d;
And teh result is this:
ITEMS
-----
(null)
I follow this tutorial: LINK
Can somebody help me ?
Regards

Answer 1

When you select apex_web_service.make_rest_request, it returns a string. The database doesn't know this is JSON data.
If you're on Oracle Database 18c or higher, you should be able to get around this by using treat ... as json:
select d.custom.items.id from (
select treat ( '{
"hasMore": false,
"items": [ {
"id": 12,
"Origin": "ALL",
"Part": "PO423S",
"Channel": "RC"
}, {
"id": 13,
"Origin": "ALL",
"Part": "LO123D",
"Channel": "RC"
}, {
"id": 14,
"Origin": "ALL",
"Part": "SD765S",
"Channel": "AP"
}
]
}' as json ) custom from dual
) d;
ITEMS
[12,13,14]
To understand why inserting the response into the table, then selecting it returns null, we'd need to see the exact JSON that's in there!