Funky IBM i Email Validation Program using SQL Regex

IBM i

Jun 13

Following on from my previous blog (basic email validation) I decided that it would much nicer to (a) have the regex stored in a data area so that we can easily play with it to try different validation scenarios and (b) lets have a shot at a much stricter validation because there is an official standard – RFC5322. Like our basic validation, this doesn’t check that it’s a valid address by checking online, but it does perform some stricter checks for which characters are being used and in which order.

So, lets start with this regex:

General Email Regex (RFC 5322 Official Standard)

(?:[a-z0-9!#$%&’*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&’*+/=?^_`{|}~-]+)*|”(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*”)@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])

*phew* that’s a load of gobbledygook.

You will notice that this regex also has lots of single quotes, double quotes and other naughtiness in it?

As an IBM i Developer I’m sure you are already cringing trying to figure out how to get this variable into your code.

So let’s tidy that variable, plonk it in a data area and create it like this:

CRTDTAARA DTAARA(LITTENN/VLD8EMAIL) TYPE(*CHAR) LEN(1024) VALUE('(?:[a-z0
-9!#$%&''*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&''*+/=?^_`{|}~-]+)*|"(?:[\x01-\x
08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f]
)*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-
9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4]
[0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\
x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])') TEXT('validate 
email regular expression')

This gives us this beautiful thing:

ibm i dtaara with regex for email validation 800x489 - Funky IBM i Email Validation Program using SQL Regex

We can then tinker with our previous code, a couple of quick little changes to the email_is_valid procedure, and simply read the regular expression in from a data area like this:

dcl-proc email_is_valid;
 dcl-pi *n IND;
   myEmail like(email);
 end-pi;
 dcl-s myCount uns(10);
 dcl-s myEmailValidationRegex varchar(1024);
 dcl-ds vld8email dtaara len(1024);

 in vld8email;
 myEmailValidationRegex = %trim(vld8email);

 exec sql
   set :myCount = regexp_count(:myEmail, :myEmailValidationRegex);

 If myCount = 1;
   return *on;
 else;
   return *off;
 endif;
end-proc;

A much nicer solution all round.

Plus the regex analyzer for this regex is way more mental:

complex email validation regex 800x714 - Funky IBM i Email Validation Program using SQL Regex

#timeforacoffee