How to remove control chars from clob, prior to creating xmltype

Question

Hi,
I am struggling with what should be really straightforward ...
I have a simple program that takes an xml file stored in a clob column and attempts to convert it into an xml type.
The program is
declare
     v_xml xmltype;
     v_jobs_clob clob := empty_clob();
begin
     dbms_lob.createtemporary(v_jobs_clob,true);
     select clob_tmp into v_jobs_clob from clob_tmp where rownum < 2;
     v_xml := XMLTYPE.createxml(v_jobs_clob);
end;
However my clob clearly contains at least one invalid character as I get this
declare
ERROR at line 1:
ORA-31011: XML parsing failed
ORA-19202: Error occurred in XML processing
LPX-00217: invalid character 7 (U+0007)
Error at line 450
ORA-06512: at "SYS.XMLTYPE", line 5
ORA-06512: at line 8
What I would like to do is to strip all the control characters from the v_jobs_clob before calling createXML.
I have tried all sorts of things, like replace etc, but to no avail.
Please help...
Ralph

Answer 1

I would have suggested that too but the [:cntrl:] character class also includes XML-valid characters such as #x9, #xA and #xD :
SQL> select level as "AsciiCode"
  2       , chr(level) as "ControlChar"
  3  from dual
  4  where regexp_like(chr(level), '[[:cntrl:]]')
  5  connect by level < 256;
AsciiCode Cont
         1 ☺
         2 ☻
         3 ♥
         4 ♦
         5 ♣
         6 ♠
         7
         8
         9
        10
        11 ♂
        12 ♀
        13
        14 ♫
        15 ☼
        16 ►
        17 ◄
        18 ↕
        19 ‼
        20 ¶
        21 §
        22 ▬
        23 ↨
        24 ↑
        25 ↓
        26 →
        27 ←
        28 ∟
        29 ↔
        30 ▲
        31 ▼
       127 ⌂
32 rows selected.