How to process validations using PL/SQL function

Question

Hi.
I created a page with a form to process DML operations against a database table. Also created a validation using PL/SQL function that returns a boolean value:
declare
v_dummy varchar2(1)
begin
select 'X'
into v_dummy
from s_customer
where id = :p2_id;
return (TRUE);
exception
when no_data_found then
return (FALSE);
when others
return (TRUE);
end;
In this case i want to send a message to the user indicating that an certain row (the one with :p2_id value) already exists in the database. The piece of code above will do the job. If this function returns true, it means the row is in the DB already.
The problem is that i don´t know what do to or how to tell htmldb that a TRUE value should issue a message or be processed as en error, whilst a FALSE means OK.
How do i tell htmldb what to do?
Suppose must do something with "expression 1" , "expression 2", etc.
Any ideas???

Answer 1

Hóla LuÃs,
when you pick the PL/SQL function body returning a boolean, it implicitly means that TRUE means OK, while FALSE means error, always.
In order to associate such error to a given form field, you have to go back to the page definiton / validations and specify the name of the item in the corresponding field.
When you first create the validation rule, this value is not present even if you ask for the error message inline with the field.
The error message text can be specified in the validation definition, if I am not wrong.
When you need to return special error messages, including dynamic content for instance, you can use the Function Returning Error Message type, which reports an error when the string returned by the function is not null. This comes in handy when you want to display an item's code, for example, rather than generic text.
Even in this case, you must go back to the validation and specify the name of the field if you want to see it inline.
Hope it helps,
Flavio