regex validation: valid matches not found

j4john Oct 4, 2006 7:30 PM

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Hi

I'm trying to use a regex to validate the format (not the content!) of email addresses. The best regex if found for this so far is

^([0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*@([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,9})$

which I've tested using http://regexlib.com/RETester.aspx

Strings which produce matches using this tester fail validation when I use the same pattern as an item-level validation on an Apex page.

I know that there are some different regex dialects out there, so maybe that's the problem...

Can anybody help out with an explanation - or even a fix :) ?

Many thanks

john

1. Re: regex validation: valid matches not found

Chet Justice Oct 4, 2006 7:43 PM (in response to j4john)

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I am not familiar with regex but I did read this great post the other day on the SQL/PLSQL forum by cd.

Introduction to regular expressions ...

If that doesn't help you, you'd probably get better help over there (hopefully from cd himself).

chet
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2. Re: regex validation: valid matches not found

j4john Oct 4, 2006 8:03 PM (in response to Chet Justice)

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Thanks Chet,

Hadn't spotted cd's thread (on which I've now created a cross-ref to this one).

john
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3. Re: regex validation: valid matches not found

60660 Oct 5, 2006 12:31 AM (in response to j4john)

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The problem seems to be a missing "*" metacharacter. I've put a small test case together:

WITH t AS (SELECT 'Test@oracle.com' email
             FROM dual
            UNION 
           SELECT '1@oracle.com' 
             FROM dual
          )
SELECT t.email 
     , REGEXP_SUBSTR(t.email, '^([0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*@([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,9})$') orig_check
     , REGEXP_SUBSTR(t.email, '^([0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*@([0-9a-zA-Z]*[-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,9})$') new_check
  FROM t
  ;

I'm going to deal with inet specific values (IP4 addresses, emails, URLs) in the second part of my regex introduction.

C.

4. Re: regex validation: valid matches not found

j4john Oct 5, 2006 1:15 AM (in response to 60660)

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Thankyou C,

Your fix does the trick.

I still don't understand why I got different results from http://regexlib.com/RETester.aspx (assuming it is POSIX compliant) and Apex.

I look forward to your next installment.

jd
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5. Re: regex validation: valid matches not found

60660 Oct 5, 2006 2:09 AM (in response to j4john)

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Maybe you should try another regex testing software? 2 out of 3 could give you a hint which implementation could have a bug.

C.
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