Get Value Of A Select Type Helper Form With Getvalue()

[tovirio]

I need to get the value of a select type:

 

renderForm(){

 

array(
     'type' => 'select',
     'label' => $this->l('Shop Category'),
     'name' => 'CategoryName',
     'options' => array(
            'query' => $query,
             'id' => 'id_feature',
             'name' => 'name'
            )
       ),

....

}

 

all works perfecly, now i want to get the value that user choose. I use this code:

 

getContent(){

 

   Tools::getValue('CategoryName');

 

}

 

 

This code return me nothing. How can i get the value that the user choose ? (the selected $query value)