Set Validation on form:Cakephp 3

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1

LoginControlller.php

namespace App\Controller;
use Cake\ORM\TableRegistry;

use App\Controller\AppController;
class LoginController extends AppController
{
public function initialize()
{
parent::initialize();

    $this->loadComponent('Flash'); // Include the FlashComponent
}

public function index()
{
	$this->set('login', $this->Login->find('all'));
    $this->set(compact('login'));	
}

public function add()
{
    $login = $this->Login->newEntity();
    if ($this->request->is('post')) {
        $login = $this->Login->patchEntity($login, $this->request->getData());
        if ($this->Login->save($login)) {
            $this->Flash->success(__('Your login has been saved.'));
            return $this->redirect(['action' => 'index']);
        }
        $this->Flash->error(__('Unable to add your login.'));
    }
    $this->set('login', $login);
}

}

add.ctp

Add User

<?php 
echo $this->Form->create($login);
echo $this->Form->control('username');
echo $this->Form->control('password');
echo $this->Form->button(__('Save Article'));

echo $this->Form->end();

?>

Model/Login.php

<?php namespace App\Model\Table; App::uses('AuthComponent', 'Controller/Component'); use Cake\ORM\Table; use Cake\Validation\Validator; class Login extends AppModel { public $validate = array('username' => array('rule' => 'notEmpty')); } ?>

validation added in Login.php is not working.Please help