Can't validate form CakePHP 3 - forms

Question

I'm new on CakePHP and I can't validate a login form. I'm getting the following error: Notice (8): Undefined variable: user [APP/Template\Users\login.ctp, line 5]
I already tried to use this code: <?= $this->Form->create('User'); ?> The error is removed but the validation doesn't works.
Can someone help me?
login.ctp:
<br>
<div class="index large-4 medium-5 large-offset-4 medium-offset-4 columns">
<div class="panel">
<h2 class="text-center">Login</h2>
<?= $this->Form->create($user); ?>
<?php
echo $this->Form->input('email');
echo $this->Form->input('password');
?>
<?= $this->Form->submit('Login', array('class' => 'button')); ?>
<?= $this->Form->end(); ?>
</div>
</div>
login function - UsersController.php:
// Login
public function login()
{
if($this->request->is('post'))
{
$user = $this->Auth->identify();
if($user)
{
$this->Auth->setUser($user);
return $this->redirect(['controller' => 'comentario']);
}
// Erro no Login
$this->Flash->error('Erro de autenticação');
}
}

Answer 1

First of all, change this line
<?= $this->Form->create($user); ?>
to this
<?= $this->Flash->render('auth') ?>
<?= $this->Form->create() ?>
Then, you can simplify your submit like this
<?= $this->Form->button(__('Login')); ?>
Make sure you create UsersTable.php in you src/Model/Table and put this code
// src/Model/Table/UsersTable.php
namespace App\Model\Table;
use Cake\ORM\Table;
use Cake\Validation\Validator;
class UsersTable extends Table
{
public function validationDefault(Validator $validator)
{
return $validator
->notEmpty('username', 'A username is required')
->notEmpty('password', 'A password is required')
}
}
It's not good using redirect the specific controller inside login method. Change it:
return $this->redirect($this->Auth->redirectUrl());
Then tell your Auth Component where user should be redirect after login
$this->loadComponent('Auth', [
'loginRedirect' => [
'controller' => 'Articles',
'action' => 'index'
],
'logoutRedirect' => [
'controller' => 'Pages',
'action' => 'display',
'home'
]
]);
And the most important. Read Authentication and Authorization Tutorial