From: Phlip <phlip2005@...>
Date: 2008-08-21T17:01:27+09:00
Subject: Re: Validation

Newb Newb wrote:

> Hi all..i am newb for rails as well as ruby

The best group for Rails questions is:

   http://groups.google.com/group/rubyonrails-talk

But you should read /Agile Web Development with Rails/, by the Daves, before 
asking any questions there.

> I have Column called Description In My Table.
> I would Like to Validate That Description Column.
> That is It Should Only Contain Texts Not Images.

Validations are not invariants, they are part of user interaction. How will your 
users put content into the description? If they post it thru a <textarea>, it 
already is only ASCII (actually UTF-8) text. <textarea> cannot absorb rich text 
input with pictures.

> What Do I DO With Using Regular Expressions?

Some validation directives accept a regexp, but you need to characterize what an 
"image" would look like in your input before bouncing it. If, for example, you 
allow users to enter raw HTML, and you will mark it up when displaying it, you 
could write a regexp against "<img". But this will fail if the user wanted a 
cleartext "<img" in their message, and it will fail to remove '<object' and 
'<embed' tags.

Read the book, then post more of your application details to the Rails-talk group!

-- 
   Phlip