Oracle 10g trigger to pass variable to xmltype.existsnode() function

Question

Hi all,
Could anyone please help me on this? It is kind of urgent.
I created a trigger below, it compiled successfully, but when I tried to insert a xml document into oracle 10g db, I got error message says:
550- Error Response
ORA-00604: error occurred at recursive SQL level 1
ORA-30625: method dispatch on NULL SELF argument is disallowed
ORA-06512: at "CONTENTDB.VALIDATE_LINK", line 11
ORA-04088: error during execution of trigger 'CONTENTDB.VALIDATE_LINK'
550 End Error Response
My trigger is:
CREATE OR REPLACE TRIGGER VALIDATE_LINK
BEFORE insert on TABLE_LINK
FOR each row
DECLARE
v_key VARCHAR2(1000);
v_count NUMBER(5);
xmldata XMLType;
begin
xmldata := :new.sys_nc_rowinfo$;
IF xmldata.existsnode('/link/key') = 1 THEN
v_key := xmldata.extract('/link/@key').getStringVal();
select count(*) into v_count from table_link WHERE (existsNode(object_value,'/link[key=v_key]') = 1 )
and (existsNode(object_value,'/link/publishingElements[TestingFlag="true"]') = 1);
if (v_count >= 1) then
raise_application_error (-20001, 'TestingFlag can only have one true value.');
end if;
end if;
end;
I have questions regarding above trigger:
1) it seems extract() doesn't work in statement below: v_key := xmldata.extract('/link/@key').getStringVal();
2) can I pass a variable v_key into xmltype.existsnode() function? if yes, what is the right format to do so?
Thanks a lot.
Honson

Answer 1

Hi Mark,
Thanks for your comments, I have added checking for xmltype object is not null logic. and my initial problem was fixed, the only last problem I am having now is xmltype.extract().
CREATE OR REPLACE TRIGGER VALIDATE_LINK
BEFORE insert on table_LINK
FOR each row
DECLARE
v_key VARCHAR2(4000);
v_count NUMBER(5);
xmldata XMLType;
v_tmp VARCHAR2(4000);
begin
xmldata := :new.sys_nc_rowinfo$;
if (xmldata is not null) then
IF xmldata.existsnode('/link/key') = 1 THEN
v_key := xmldata.extract('/link/key').getStringVal();
v_tmp := '/link[key=' || v_key || ']';
select count(*) into v_count from cibc_link WHERE (existsNode(object_value,v_tmp) = 1 )
and (existsNode(object_value,'/link/publishingElements[TestingFlag="true"]') = 1);
if (v_count >= 1) then
raise_application_error (-20001, 'TestingFlag can only have one true value.');
end if;
end if;
end if;
end;
I am expecting this statement:
v_key := xmldata.extract('/link/key').getStringVal();
return v_key := content.link.viewPrintableVISACreditCard
but now it always returns like this:
v_key := <key>content.link.viewPrintableVISACreditCard</key>
I don't want the xml tag <key></key> returned by extract().getStringVal() function.
Could you or anyone please help?
Thanks.
Honson