Simple ZF2 validation using inputProviderInterface

YourForm.php

<?php

namespace Application\Form;

use Zend\Form\Form;
use Zend\Validator;
use Zend\InputFilter\InputFilterProviderInterface;

class YourForm extends Form implements InputFilterProviderInterface
{

  public function __construct()
	{
		parent::__construct('your-form-name');

		$this->add(array(
			'name' => 'persons_name',
			'type' => 'text';
		));
		
		$this->add(array(
			'name' => 'dynamically_added',
			'type' => 'text'
		));
		
		$this->getInputFilter()->add(array(
                        'name' => 'dynamically_added',
                        'required' => true,
                        'validators' => array(
                            new Validator\LessThan(
                                array(
                                    'max' => 1,
                                    'inclusive' => true
                                )
                            )
                	)
	        ));

		$this->add(array(
			'name' => 'amount',
			'type' => 'text';
		));

	}

    public function getInputFilterSpecification()
    {
        return array(
            'persons_name' => array(
                'required' => true,
                'allow_empty' => true,
            ),
            'amount' => array(
                'required' => true,
                'allow_empty' => true,
                'validators' => array(
                	new Validator\LessThan(
                		array(
                			'max' => 10
                		)
                	),
                	new Validator\Callback(
                		array(
                			'callback' => function ($value) {
						return $value / 2;
					}
                		)
                	)
                )
            ),
        );
    }

}