php - How to access a public function from a model inside a controller in magento? -

\ magento issue. have controller called imagescontroller.php where

class my_sell_imagescontroller extends mage_core_controller_front_action 

i extending/inhering core controller

now, have class

class my_advert_model_advert extends mage_core_model_abstract {  public function isvalid($arrsteptpcheck){ ... 

i access isvalid inside my_sell_imagescontroller maybe like

 $advert = mage::registry('current_advert');  $arrerror = $this->isvalid(array('step1')); 

but gives me

fatal error: call undefined method my_sell_imagescontroller::isvalid() in .....imagescontroller.php 

i new magento backend. please help?

try code

mage::getmodel('advert/advert')->isvalid(array('step1')); 

or

my_advert_model_advert::isvalid(array('step1'));