PL/SQL UTL_HTTP.REQUEST - Curly Braces/Semicolon - oracle

Question

I'm trying to call a URL using the UTL_HTTP package in Oracle Autonomous Database and getting an ORA-06512:
ORA-06502: PL/SQL: numeric or value error: character to number conversion error
ORA-06512: at "SYS.UTL_HTTP", line 1810
ORA-06512: at "SYS.UTL_HTTP", line 144
ORA-06512: at "SYS.UTL_HTTP", line 1745
ORA-06512: at line 1
06502. 00000 - "PL/SQL: numeric or value error%s"
*Cause: An arithmetic, numeric, string, conversion, or constraint error
occurred. For example, this error occurs if an attempt is made to
assign the value NULL to a variable declared NOT NULL, or if an
attempt is made to assign an integer larger than 99 to a variable
declared NUMBER(2).
*Action: Change the data, how it is manipulated, or how it is declared so
that values do not violate constraints.
All network ACLS etc. are configured correctly.
The URL in question requires JSON directly in the URL which I understand is bad practice, however I don't have control over the API. If I remove the curly braces ( {} ) and semicolons ( : ), the request using UTL_HTTP works but the output is incorrect as the JSON becomes invalid.
I've tried encoding the URL using an online encoder as well as the UTL_URL.ESCAPE function, which gives the same error as above.
The encoding from UTL_URL.ESCAPE IS:
An example of the URL format is:
https://example.com/rest.php?entity=contact&action=get&json={"name": "Lorum Ipsum", "end_date": {"IS NULL": 1}, "return": "id,contact_id"}
I've tried a straight select using utl_http.request:
SELECT UTL_HTTP.REQUEST('https://example.com/rest.php?entity=contact&action=get&json={"name": "Lorum Ipsum", "end_date": {"IS NULL": 1}, "return": "id,contact_id"}') FROM DUAL;
And calling using PL/SQL:
declare
req UTL_HTTP.REQ;
resp UTL_HTTP.RESP;
val VARCHAR2(2000);
str varchar2(1000);
begin
req := UTL_HTTP.BEGIN_REQUEST('https://example.com/rest.php?entity=contact&action=get&json={"name": "Lorum Ipsum", "end_date": {"IS NULL": 1}, "return": "id,contact_id"}');
resp := UTL_HTTP.GET_RESPONSE(req);
LOOP
UTL_HTTP.READ_LINE(resp, val, TRUE);
DBMS_OUTPUT.PUT_LINE(val);
END LOOP;
UTL_HTTP.END_RESPONSE(resp);
EXCEPTION
WHEN UTL_HTTP.END_OF_BODY
THEN
UTL_HTTP.END_RESPONSE(resp);
END;
/
How do I call this url using UTL_HTTP?

Answer 1

They talk about this a bit in the UTL_URL documentation, but colons are reserved characters - they're valid in some parts of a URL, but not in others. (Curly braces are not allowed at all.) There's been some debate about whether or not they're valid in the Query portion of a URL - the ABNF in the RFC seems to say yes, but a lot of implementations don't allow it.
By default, UTL_URL.ESCAPE doesn't escape reserved characters (because that would screw up the https:// part, etc), but you can change that by passing TRUE as the second argument. In general, best practice seems to be escaping reserved characters in any query string that might contain them:
req := UTL_HTTP.BEGIN_REQUEST('https://example.com/rest.php?entity=contact&action=get&json='
|| utl_url.escape('{"name": "Lorum Ipsum", "end_date": {"IS NULL": 1}, "return": "id,contact_id"}'
,TRUE));
See if that helps?