php - How add custom attribute in zend framework 2 using zend from -

i want use angularjs in zend framework project , in project forms generated using zend form. how can add angular directive such "ng-model" in form elements whenever trying add custom attribute in zend-form elements (input, select etc) in view not getting attribute ----

here lead form

class leadform extends form {

public function __construct() {      parent::__construct('lead_form');      $this->setattributes(array(         'action' => '',         'method' => 'post',         'name' => 'lead_form',         'id' => 'lead_form',         'class' => 'smart-form',         'role' => 'form',         'novalidate' => 'novalidate'     ));      $this->add(array(         'name' => 'first_name',         'type' => 'text',         'options' => array(             'label' => 'first name',         ),         'attributes' => array(             'class' => 'form-control validate[required,custom[onlylettersp]]',                             'placeholder' => 'first name',                             **'ng-model' => "first_name", // attribute not generating in view**         ),                 )); } 

}

here controller calling form , send view displaying

$createleadform = new \admin\form\leadform();  return new viewmodel(array(             'form' => $createleadform, )); 

here code in view showing element

<?php echo $this->forminput($this->form->get('first_name')); ?> 

but after prinnting form element getting see no "ng-model" in input element

<input type="text" value="" placeholder="first name" class="form-control validate[required,custom[onlylettersp]]" name="first_name" > 

i have set 1 attribute "ng-model " attribute not appearing in view

i want element (using zend form ) -

<input type="text" ng-model="first_name" value="" placeholder="first name" class="form-control validate[required,custom[onlylettersp]]" name="first_name" > 

how can using zend form , need change in form , why can not able add custom attribute? please me.

thanks in advance

you can use data-ng-*:

$this->add(array(     // ...     'attributes' => array(         // ...         'data-ng-model' => 'first_name',     ),             ));