Pass Checkbox Parameters from HTML Form to a stored procedure

Question

I'm still looking for a solution to my forms problem. FYI, I'm not using Applications Express to build my application--I'm using straight PL/SQL. I need to know how to pass checkbox parameters from my Web form. I'm allowing folks to select one or more checkboxes on a form that will call a delete function to delete the selected records. What I read in Oracle's "Database Application Developer's Guide - Fundamentals" isn't helpful to me. If someone would point me to some examples, maybe I could see what I'm doing wrong. Here's what was written in "Database Application Developer's Guide - Fundamentals":
All the checkboxes with the same NAME attribute make up a checkbox group. If none of the checkboxes in a group is checked, the stored procedure receives a null value for the corresponding parameter.
If one checkbox in a group is checked, the stored procedure receives a single VARCHAR2 parameter.
If more than one checkbox in a group is checked, the stored procedure receives a parameter with the PL/SQL type TABLE OF VARCHAR2. You must declare a type like this, or use a predefined one like OWA_UTIL.IDENT_ARR. To retrieve the values, use a loop:
CREATE OR REPLACE PROCEDURE handle_checkboxes ( checkboxes owa_util.ident_arr )
AS
BEGIN
FOR i IN 1..checkboxes.count
LOOP
htp.print('<p>Checkbox value: ' || checkboxes(i));
END LOOP;
END;
SHOW ERRORS;

Answer 1

I'm not sure I understand what your issue is.
If your web form has the following checkboxes defined all with the same name:
<input type="checkbox" name="attrib" value="1">one</input>
<input type="checkbox" name="attrib" value="2">two</input>
<input type="checkbox" name="attrib" value="3">three</input>Then you would create and register a procedure to handle the form submission that has a parameter with the name attrib of type owa_util.ident_arr e.g.:
create or replace procedure handle_form(attrib owa_util.ident_arr) as
  iter number;
begin
  for iter in attrib.first .. attrib.last loop
    -- do something with attrib(iter)
  end loop;
end;
/Now the one problem with this handler (or any form handler for that matter) is that if the user selects none of the check boxes, or no value for any of the expected parameters, the handler would be called with some parameters missing or with out any parameters passed to it, and the call will error out.
To get around that you need to provide default values for all the parameters passed to your handler including the ident_arr parameters, however with ident_arr parameters that's difficult to do with standalone procedures. If you place your procedure in a package you can define package level variables of the appropriate types that can be used as default values:
create or replace package my_web as
  empty_arr owa_util.ident_arr;
  procedure handle_form(attrib owa_util.ident_arr := empty_arr);
end my_web;
create or replace package body my_web as
  procedure handle_form(attrib owa_util.ident_arr := empty_arr) as
    iter number;
  begin
    for iter in attrib.first .. attrib.last loop
      -- do something with attrib(iter)
    end loop;
  end;
end my_web;
/now when you hit the situation where the user doesn't select any check boxes, the call to handle_form won't err out due to missing parameters, and the empty_arr won't have any elements to iterate over so the loop in the procedure body will be fine and you will be able to retrieve each selected check box value from the attrib array when you iterate over it.