pls-00306 error when trying to print output - oracle

Question

This code block returns error pls-00306 wrong number or types of arguments in call to 'put_line':
SET SERVEROUTPUT ON
DECLARE
ch varchar2(16);
cursor ebs_user_cur
is
select xmlagg(xmlelement("r", ch)).extract('//text()').getstringval()
from
(
select distinct first_value(ch) over (partition by lower(ch))
from (
select substr('abcd#efghijklmn#pqrstuvwxyzABC$DEFGHIJK$LMNPQR!STUVWXYZ1!23456789',
level, 1) ch
from dual
connect by level <= 59
order by dbms_random.value
)
where rownum <= dbms_random.value(18,18)
);
l_passwd ebs_user_cur%ROWTYPE;
BEGIN
open ebs_user_cur;
loop
fetch ebs_user_cur into l_passwd;
DBMS_OUTPUT.PUT_LINE(l_passwd);
EXIT WHEN l_passwd%NOTFOUND;
END LOOP;
close ebs_user_cur;
END;
Where is mistake?
Thank you

Answer 1

You should give column alias in your cursors
You should specify exact field name in l_passwd.{field_name}:
SET SERVEROUTPUT ON
DECLARE
ch varchar2(16);
cursor ebs_user_cur
is
select xmlagg(xmlelement("r", ch)).extract('//text()').getstringval()
as res -- <<< see here
from
(
select distinct first_value(ch) over (partition by lower(ch))
from (
select substr('abcd#efghijklmn#pqrstuvwxyzABC$DEFGHIJK$LMNPQR!STUVWXYZ1!23456789',
level, 1) ch
from dual
connect by level <= 59
order by dbms_random.value
)
where rownum <= dbms_random.value(18,18)
);
l_passwd ebs_user_cur%ROWTYPE;
BEGIN
open ebs_user_cur;
loop
fetch ebs_user_cur into l_passwd;
DBMS_OUTPUT.PUT_LINE(l_passwd.res); -- <<< .res here
EXIT WHEN l_passwd%NOTFOUND;
END LOOP;
close ebs_user_cur;
END;