From: Justin Collins <justincollins@...>
Date: 2009-07-14T18:38:57+09:00
Subject: Re: a regex that does not contain comma

Sijo Kg wrote:
> Hi
>    Could anybody please tell how to write the validates_format_of a
> string(in rails) which is only valid when it does not contain a
> comma.For example
>
> The are valid
>
> hi welcome
> Hello
> h123 kk
> hh gg hh
>
> The are not valid
>
> Hello,
> Hi , world
> Hello,welcome
>
> Thanks in advnce
> Sijo
>   

I believe

/^[^,]*$/

will do what you need, including matching empty strings. rubular.com is 
a good place to try out regular expressions.

-Justin