Yii2 how to properly validate email?

Question

Yii

Started learning yii2. Doesn't validate email for existence. Here is the code:
sitecontroller.php

public function actionRegister()
    {
        $model = new RegisterForm();
        $model->load(Yii::$app->request->post());
        return $this->render('register', ['model' => $model]);
    }

RegisterForm.php

<?php

namespace app\models;
use yii\base\Model;

/**
 * Description of RegisterForm
 *
 * @author kvonosan
 */
class RegisterForm extends Model{
    public $login;
    public $password;
    public $email;
    public $username;
    
    
    public function rules() {
        return [
            [['login', 'password', 'email'], 'required'],
            ['email', 'email'],
            ['email', 'validateEmail', 'message'=>'Email already exists!'],
        ];
    }
    
    public function validateEmail($attribute, $params) {
        $users = new users();
        if ($users->EmailExist($this->email)) {
            $this->addError('email', 'This email already exist.');
        }
    }
}

users.php

<?php

namespace app\models;
use Yii;

/**
 * Description of users
 *
 * @author kvonosan
 */
class users
{
    public function register($login, $password, $username, $email) {
        if (empty($login) || empty($password) || empty($email)) {
            return false;
        }
        if (empty($username)) {
            $username = 'Аноним';
        }
        $sql = "INSERT INTO users (id, login, password, username, fotos, email)"
            . "VALUES (NULL , :login, :password, :username, NULL , :email);";
        $command = Yii::$app->db->createCommand($sql);
        $result = $command->execute(array(':login' => $login, ':password' => $password,
                    ':username' => $username, ':email' => $email));
        Yii::trace("insert into execute return " . $result);
        return true;
    }
    
    public function EmailExist($email) {
        if (empty($email)) {
            return true;
        }
        $sql = "SELECT COUNT(*) FROM users WHERE email=:email";
        $command = Yii::$app->db->createCommand($sql);
        $result = $command->execute(array(':email' => $email));
        if ($result === 1) {
            return true;
        } else {
            return false;
        }
    }
}

register.php

<?php

use yii\helpers\Html;
use yii\bootstrap\ActiveForm;

$this->title = 'Register';
?>

<div class="site-register">
    <h1><?= Html::encode($this->title) ?></h1>
    <div class="row">
        <div class="col-lg-4">
            <?php $form = ActiveForm::begin(['id' => 'register-form']) ?>
            <?= $form->field($model, 'login')->textInput(['autofocus' => true]) ?>
            <?= $form->field($model, 'password') ?>
            <?= $form->field($model, 'email') ?>
            <?= $form->field($model, 'username') ?>
            <div class="form-group">
                    <?= Html::submitButton('Submit', ['class' => 'btn btn-primary', 'name' => 'register-button']) ?>
            </div>
            <?php ActiveForm::end(); ?>
        </div>
    </div>
</div>

Link love.peshkova-natalia.ru/site/register
There is an email [email protected] in the database, in theory it should swear, but nothing happens.
Tell me what's wrong, please.

Answer 1

Good evening.
From documentation
Want to check if an email address is unique?
I think it will be better

['email', 'unique', 'targetClass' => self::className(),
                                'message' => 'Email already exists!'],