Problem setting custom validation rules in Cakephp

I creating a custom validation rule in my cakephp model.

        开发者_C百科'article' => array(
                'rule' => '/^[a-z0-9#.,&; ]{2,255}$/i',
                'required' => true,
                'allowEmpty' => false,
                'message' => 'Alphabets and numbers only(3,255).'
        ),

This works fine. But It stops working, throws a error in model, when I add forward slash [/]. I can't understand why forward causes a problem.

I appreciate any help.

Thanks.

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As stated in your other question, read about preg_match() patterns in the php manual. This function is used internally in the framework.