ApEx How 2 turn a multiselect list value (eg. 1:2:3:4 ) into (1,2,3,4)

Question

ApEx newbie here,
I'm trying to get the output of a multi select list into an in list of a sql query for a report. The error message I'm getting is report error:
ORA-01722: invalid number. (The inlist is a list of id numbers, and the data type for this column in the database is NUMBER)
I've got a page item called P3_x which is populated from a MultiSelect list. I learned that these come out as colon delimited strings. (found a reference to hidden items in a blog that helped me figure this out)
So I created a hidden item called P3_x_in_list which does this:
Select '('|| regexp(:p3_x,':',',')||')' from dual which turns this into a comma separated list, like so: (1,2,3,4)
I put this hidden item, P3_X_IN_LIST into the sql in my report region
So in the report my sql looks like:
select a, b, c
from t1
where id in: P3_x_in_list
and some_date between :P1_X and :P2_X
For some reason it throws an invalid number error when it runs. I haven't been able to find anything in the documentation or on the web that sheds any light on this. I'm hoping that there is a benevolent, experienced developer that can point me in the right direction. The debuging information from the page is below:
Here is the debugging information
0.24: ...Session State: Save "P3_X" - saving same value: "1:2:3:4:5"
0.24: ...Session State: Save "P1_X" - saving same value: "01-DEC-2008"
0.24: ...Session State: Save "P2_X" - saving same value: "04-DEC-2008"
0.30: ...Session State: Save Item "P3_X_IN_LIST" newValue="(1,2,3,4,5)" "escape_on_input="N"
0.30: Processing point: ON_SUBMIT_BEFORE_COMPUTATION
0.46: show report
0.46: determine column headings
0.46: parse query as: my_schema
1.76: binding: ":P3_X_IN_LIST"="P3_X_IN_LIST" value="(1,2,3,4,5)"
2.64: binding: ":P2_X"="P2_X" value="04-DEC-2008"
report error:
ORA-01722: invalid number
ORA-02063: preceding line from my_schema
3.23: Computation point: AFTER_BOX_BODY
3.23: Processing point: AFTER_BOX_BODY
3.23: Computation point: BEFORE_FOOTER
3.23: Processing point: BEFORE_FOOTER
3.23: Show page tempate footer

Answer 1

Well, let's say you had a SQL statement like
select * from obj where object_id in 12345
where object_id is defined to be a number type.
Now, if you replace the literal '12345' with a bind variable and then bind "(1,2,3,4,5)" to this bind variable it will be clear why the SQL fails.
As for using pipeline functions it is pretty straightforwad
Here's an example
CREATE OR REPLACE TYPE vc_array_1 AS TABLE OF VARCHAR2 (50);
CREATE OR REPLACE FUNCTION get_list (
   p_string      IN   VARCHAR2,
   p_delimiter   IN   VARCHAR2 DEFAULT ':'
   RETURN vc_array_1 PIPELINED
IS
    l_string     varchar2(32000);
    l_array     wwv_flow_global.vc_arr2;
BEGIN
   l_array := apex_util.STRING_TO_TABLE(p_string,p_delimiter);
   for i in l_array.first..l_array.last loop
      pipe row (trim(l_array(i)));
   end loop;
   return;
end;
select column_value from table (get_list('1:2:3:4:5'));Your query can now be
select a, b, c
from t1
where id in (select column_value from table get_list(: P3_x_in_list)) )   
and some_date between :P1_X and :P2_XVarad