Yii Model On Insert, Update And Change Password And Alphanumeric password

In Model.php Add this rules

public function rules()

{

        

   return array(

 array('username, password,confirmpassword,firstname,

               lastname, email,address, companyname, usertype,

               isactive',       'required',

               'on'=>'insert'),

        array('username, firstname,lastname, email,address,

        companyname, usertype,isactive', 'required',

              'on'=>'updateuser'),

        array('password,confirmpassword','required',

           'on'=>'changepassword'),

            array('password', 'compare', 'compareAttribute' =>

              'confirmpassword','on'=>'insert,changepassword'),

             

           array('password','passwordalphanumeric',

             'on'=>'changepassword'),   

            

            array('username,password,firstname,lastname,

            email,address,companyname,phoneno,mobileno',

            'filter', 'filter'=>'trim'),

}

public function passwordalphanumeric($attribute_name,$params){

    if(!empty($this->password)){

       if (preg_match('~^[a-z0-9]*[0-9][a-z0-9]*$~i',$this->password)) {

            // $subject is alphanumeric and contains at least 1 number

       } else {   // failed

           $this->addError($attribute_name,'Enter password with digits');

       }       

    }

}