To begin with, yii2 basic must already be installed. How to do this is described here: Short instruction. How to install Yii 2 basic.

Configure the connection to the database in the file /config/db.php and proceed.

Add authorization on the site in Yii2 basic

Open the console and add the migration to create the User table

yii migrate/create create_user_table

Open the file with the migration /migration/m000000_000000_create_user_table.php and add the code for creating the migration, we will not reinvent the wheel, and we will do the same as in the version advanced:

<?php

use yii\db\Migration;

class m000000_000000_create_user_table extends Migration
{

    public function up()
    {
        $tableOptions = null;

        if ($this->db->driverName === 'mysql') {
            $tableOptions = 'CHARACTER SET utf8 COLLATE utf8_unicode_ci ENGINE=InnoDB';
        }

        $this->createTable('user', [
            'id' => $this->primaryKey(),
            'username' => $this->string()->notNull()->unique(),
            'auth_key' => $this->string(32)->notNull(),
            'password_hash' => $this->string()->notNull(),
            'password_reset_token' => $this->string()->unique(),
            'email' => $this->string()->notNull()->unique(),
            'status' => $this->smallInteger()->notNull()->defaultValue(10),
            'created_at' => $this->integer()->notNull(),
            'updated_at' => $this->integer()->notNull(),
        ], $tableOptions);
    }

    public function down()
    {
        $this->dropTable('user');
    }

}

After saving the edits in the migration file (copy only the methods code up() and down()), execute it in the console:

yii migrate

Edit model /models/User.php:

<?php

namespace app\models;

use Yii;
use yii\base\NotSupportedException;
use yii\behaviors\TimestampBehavior;
use yii\db\ActiveRecord;
use yii\web\IdentityInterface;

/**
 * User model
 *
 * @property integer $id
 * @property string $username
 * @property string $password_hash
 * @property string $password_reset_token
 * @property string $email
 * @property string $auth_key
 * @property integer $status
 * @property integer $created_at
 * @property integer $updated_at
 * @property string $password write-only password
 */
class User extends ActiveRecord implements IdentityInterface
{
    const STATUS_DELETED = 0;
    const STATUS_ACTIVE = 10;

    /**
     * @inheritdoc
     */
    public static function tableName()
    {
        return '{{%user}}';
    }

    /**
     * @inheritdoc
     */
    public function behaviors()
    {
        return [
            TimestampBehavior::className(),
        ];
    }

    /**
     * @inheritdoc
     */
    public function rules()
    {
        return [
            ['status', 'default', 'value' => self::STATUS_ACTIVE],
            ['status', 'in', 'range' => [self::STATUS_ACTIVE, self::STATUS_DELETED]],
        ];
    }

    /**
     * @inheritdoc
     */
    public static function findIdentity($id)
    {
        return static::findOne(['id' => $id, 'status' => self::STATUS_ACTIVE]);
    }

    /**
     * @inheritdoc
     */
    public static function findIdentityByAccessToken($token, $type = null)
    {
        throw new NotSupportedException('"findIdentityByAccessToken" is not implemented.');
    }

    /**
     * Finds user by username
     *
     * @param string $username
     * @return static|null
     */
    public static function findByUsername($username)
    {
        return static::findOne(['username' => $username, 'status' => self::STATUS_ACTIVE]);
    }

    /**
     * @inheritdoc
     */
    public function getId()
    {
        return $this->getPrimaryKey();
    }

    /**
     * @inheritdoc
     */
    public function getAuthKey()
    {
        return $this->auth_key;
    }

    /**
     * @inheritdoc
     */
    public function validateAuthKey($authKey)
    {
        return $this->getAuthKey() === $authKey;
    }

    /**
     * Validates password
     *
     * @param string $password password to validate
     * @return bool if password provided is valid for current user
     */
    public function validatePassword($password)
    {
        return Yii::$app->security->validatePassword($password, $this->password_hash);
    }

    /**
     * Generates password hash from password and sets it to the model
     *
     * @param string $password
     */
    public function setPassword($password)
    {
        $this->password_hash = Yii::$app->security->generatePasswordHash($password);
    }

    /**
     * Generates "remember me" authentication key
     */
    public function generateAuthKey()
    {
        $this->auth_key = Yii::$app->security->generateRandomString();
    }

}

Authorization is ready, now we will add a user to check authorization. Open the controller /controllers/SiteController.php and add the action to the end of the controller which will help us add the user:

public function actionAddAdmin() {
    $model = User::find()->where(['username' => 'admin'])->one();
    if (empty($model)) {
        $user = new User();
        $user->username = 'admin';
        $user->email = 'admin@devreadwrite.com';
        $user->setPassword('admin');
        $user->generateAuthKey();
        if ($user->save()) {
            echo 'good';
        }
    }
}

Run the action: site.com/web/index.php?r=site/add-admin and check the authorization site.com/web/index.php?r=site/login

After successful authorization, the AddAdmin action can be deleted as a useless item.

If you only need authorization via a database in Yii2 basic, then you can end this. If in addition to authorizing through the database on the site you need to add registration and password recovery, then continue.

Add registration to the site in Yii2 basic

First, create a model for the registration forms, for this you need to create a file /models/SignupForm.php with the following content:

<?ph

namespace app\models;

use Yii;
use yii\base\Model;

/**
 * Signup form
 */
class SignupForm extends Model
{

    public $username;
    public $email;
    public $password;

    /**
     * @inheritdoc
     */
    public function rules()
    {
        return [
            ['username', 'trim'],
            ['username', 'required'],
            ['username', 'unique', 'targetClass' => '\app\models\User', 'message' => 'This username has already been taken.'],
            ['username', 'string', 'min' => 2, 'max' => 255],
            ['email', 'trim'],
            ['email', 'required'],
            ['email', 'email'],
            ['email', 'string', 'max' => 255],
            ['email', 'unique', 'targetClass' => '\app\models\User', 'message' => 'This email address has already been taken.'],
            ['password', 'required'],
            ['password', 'string', 'min' => 6],
        ];
    }

    /**
     * Signs user up.
     *
     * @return User|null the saved model or null if saving fails
     */
    public function signup()
    {

        if (!$this->validate()) {
            return null;
        }

        $user = new User();
        $user->username = $this->username;
        $user->email = $this->email;
        $user->setPassword($this->password);
        $user->generateAuthKey();
        return $user->save() ? $user : null;
    }

}

Next, in /controllers/SiteController.php in use, add registration model SignupForm and action signup:

<?php

namespace app\controllers;

//...

use app\models\LoginForm;
use app\models\ContactForm;
use app\models\SignupForm;

class SiteController extends Controller
{

    //...

    public function actionSignup()
    {
        $model = new SignupForm();

        if ($model->load(Yii::$app->request->post())) {
            if ($user = $model->signup()) {
                if (Yii::$app->getUser()->login($user)) {
                    return $this->goHome();
                }
            }
        }

        return $this->render('signup', [
            'model' => $model,
        ]);
    }

}

Next, you need to add a view for registration, add a file /views/site/signup.php with the following content:

<?php

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

$this->title = 'Signup';
$this->params['breadcrumbs'][] = $this->title;
?>
<div class="site-signup">
    <h1><?= Html::encode($this->title) ?></h1>
    <p>Please fill out the following fields to signup:</p>
    <div class="row">
        <div class="col-lg-5">

            <?php $form = ActiveForm::begin(['id' => 'form-signup']); ?>
                <?= $form->field($model, 'username')->textInput(['autofocus' => true]) ?>
                <?= $form->field($model, 'email') ?>
                <?= $form->field($model, 'password')->passwordInput() ?>
                <div class="form-group">
                    <?= Html::submitButton('Signup', ['class' => 'btn btn-primary', 'name' => 'signup-button']) ?>
                </div>
            <?php ActiveForm::end(); ?>

        </div>
    </div>
</div>

And the last thing you need to do is add registration to the menu. Open the file /views/layouts/main.php find the menu widget and add the registration item, after which the widget with the following form:

<?php

NavBar::begin([
    'brandLabel' => 'My Company',
    'brandUrl' => Yii::$app->homeUrl,
    'options' => [
        'class' => 'navbar-inverse navbar-fixed-top',
    ],
]);

echo Nav::widget([
    'options' => ['class' => 'navbar-nav navbar-right'],
    'items' => [
        ['label' => 'Home', 'url' => ['/site/index']],
        ['label' => 'About', 'url' => ['/site/about']],
        ['label' => 'Contact', 'url' => ['/site/contact']],
        Yii::$app->user->isGuest ? (
            ['label' => 'Login', 'url' => ['/site/login']]
        ) : (
            '<li>'
            . Html::beginForm(['/site/logout'], 'post')
            . Html::submitButton(
                'Logout (' . Yii::$app->user->identity->username . ')',
                ['class' => 'btn btn-link logout']
            )
            . Html::endForm()
            . '</li>'
        )
    ],
]);

NavBar::end();
?>

Full code:

<?php

NavBar::begin([
    'brandLabel' => 'My Company',
    'brandUrl' => Yii::$app->homeUrl,
    'options' => [
        'class' => 'navbar-inverse navbar-fixed-top',
    ],
]);

$menuItems = [
    ['label' => 'Home', 'url' => ['/site/index']],
    ['label' => 'About', 'url' => ['/site/about']],
    ['label' => 'Contact', 'url' => ['/site/contact']],
];

if (Yii::$app->user->isGuest) {
    $menuItems[] = ['label' => 'Signup', 'url' => ['/site/signup']];
    $menuItems[] = ['label' => 'Login', 'url' => ['/site/login']];
} else {
    $menuItems[] = '<li>'
        . Html::beginForm(['/site/logout'], 'post')
        . Html::submitButton(
            'Logout (' . Yii::$app->user->identity->username . ')',
            ['class' => 'btn btn-link logout']
        )
        . Html::endForm()
        . '</li>';
}

echo Nav::widget([
    'options' => ['class' => 'navbar-nav navbar-right'],
    'items' => $menuItems,
]);

NavBar::end();
?>

Now we have registration and authorization in Yii2 basic.

For full functionality only need to do reset and password recovery.

Add password recovery on the site in Yii2 basic

First, you need to modify the /models/User.php model and add several methods to create and reset the token of password:

public static function findByPasswordResetToken($token)
{
    if (!static::isPasswordResetTokenValid($token)) {
        return null;
    }
    return static::findOne([
        'password_reset_token' => $token,
        'status' => self::STATUS_ACTIVE,
    ]);
}
public static function isPasswordResetTokenValid($token)
{
    if (empty($token)) {
        return false;
    }
    $timestamp = (int) substr($token, strrpos($token, '_') + 1);
    $expire = Yii::$app->params['user.passwordResetTokenExpire'];
    return $timestamp + $expire >= time();
}
public function generatePasswordResetToken()
{
    $this->password_reset_token = Yii::$app->security->generateRandomString() . '_' . time();
}
public function removePasswordResetToken()
{
    $this->password_reset_token = null;
}

As a result, the model /models/User.php will look like this:

<?php

namespace app\models;

use Yii;
use yii\base\NotSupportedException;
use yii\behaviors\TimestampBehavior;
use yii\db\ActiveRecord;
use yii\web\IdentityInterface;

class User extends ActiveRecord implements IdentityInterface
{
    const STATUS_DELETED = 0;
    const STATUS_ACTIVE = 10;

    public static function tableName()
    {
        return '{{%user}}';
    }

    public function behaviors()
    {
        return [
            TimestampBehavior::className(),
        ];
    }

    public function rules()
    {
        return [
            ['status', 'default', 'value' => self::STATUS_ACTIVE],
            ['status', 'in', 'range' => [self::STATUS_ACTIVE, self::STATUS_DELETED]],
        ];
    }

    public static function findIdentity($id)
    {
        return static::findOne(['id' => $id, 'status' => self::STATUS_ACTIVE]);
    }

    public static function findIdentityByAccessToken($token, $type = null)
    {
        throw new NotSupportedException('"findIdentityByAccessToken" is not implemented.');
    }

    public static function findByUsername($username)
    {
        return static::findOne(['username' => $username, 'status' => self::STATUS_ACTIVE]);
    }

    public static function findByPasswordResetToken($token)
    {

        if (!static::isPasswordResetTokenValid($token)) {
            return null;
        }

        return static::findOne([
            'password_reset_token' => $token,
            'status' => self::STATUS_ACTIVE,
        ]);
    }

    public static function isPasswordResetTokenValid($token)
    {

        if (empty($token)) {
            return false;
        }

        $timestamp = (int) substr($token, strrpos($token, '_') + 1);
        $expire = Yii::$app->params['user.passwordResetTokenExpire'];
        return $timestamp + $expire >= time();
    }

    public function getId()
    {
        return $this->getPrimaryKey();
    }

    public function getAuthKey()
    {
        return $this->auth_key;
    }

    public function validateAuthKey($authKey)
    {
        return $this->getAuthKey() === $authKey;
    }

    public function validatePassword($password)
    {
        return Yii::$app->security->validatePassword($password, $this->password_hash);
    }

    public function setPassword($password)
    {
        $this->password_hash = Yii::$app->security->generatePasswordHash($password);
    }

    public function generateAuthKey()
    {
        $this->auth_key = Yii::$app->security->generateRandomString();
    }

    public function generatePasswordResetToken()
    {
        $this->password_reset_token = Yii::$app->security->generateRandomString() . '_' . time();
    }

    public function removePasswordResetToken()
    {
        $this->password_reset_token = null;
    }

}

The method of checking token of password reset isPasswordResetTokenValid uses the variable user.passwordResetTokenExpire to reset password token, it must be specified in the file /congif/params.php:

<?php
return [
    'adminEmail' => 'admin@example.com',
    'user.passwordResetTokenExpire' => 3600,
];

Next, you must add the request form model to change the password and the password change form model. Total 2 models. First, we'll add the model of the request form to change the password /models/PasswordResetRequestForm.php with the following content:

<?php

namespace app\models;

use Yii;
use yii\base\Model;

/**
 * Password reset request form
 */
class PasswordResetRequestForm extends Model
{
    public $email;

    /**
     * @inheritdoc
     */
    public function rules()
    {
        return [
            ['email', 'trim'],
            ['email', 'required'],
            ['email', 'email'],
            ['email', 'exist',
                'targetClass' => '\app\models\User',
                'filter' => ['status' => User::STATUS_ACTIVE],
                'message' => 'There is no user with such email.'
            ],
        ];
    }

    /**
     * Sends an email with a link, for resetting the password.
     *
     * @return bool whether the email was send
     */
    public function sendEmail()
    {
        /* @var $user User */
        $user = User::findOne([
            'status' => User::STATUS_ACTIVE,
            'email' => $this->email,
        ]);

        if (!$user) {
            return false;
        }

        if (!User::isPasswordResetTokenValid($user->password_reset_token)) {
            $user->generatePasswordResetToken();
            if (!$user->save()) {
                return false;
            }
        }

        return Yii::$app
            ->mailer
            ->compose(
                ['html' => 'passwordResetToken-html', 'text' => 'passwordResetToken-text'],
                ['user' => $user]
            )
            ->setFrom([Yii::$app->params['supportEmail'] => Yii::$app->name . ' robot'])
            ->setTo($this->email)
            ->setSubject('Password reset for ' . Yii::$app->name)
            ->send();
    }

}

The model will send a confirmation to email for the password change. For this, it uses 2 layouts (html and text), we already have html, we need to add text. To do this, create a file /mail/layouts/text.php With the following content:

<?php
use yii\helpers\Html;
?>
<?php $this->beginPage() ?>
<?php $this->beginBody() ?>
<?= $content ?>
<?php $this->endBody() ?>
<?php $this->endPage() ?>

Also it is necessary to create 2 representations of the letter (html and text version). We will create an html version of the mail view, for this we create a file /mail/passwordResetToken-html.php with the following content:

<?php

use yii\helpers\Html;

$resetLink = Yii::$app->urlManager->createAbsoluteUrl(['site/reset-password', 'token' => $user->password_reset_token]);
?>

<div class="password-reset">
    <p>Hello <?= Html::encode($user->username) ?>,</p>
    <p>Follow the link below to reset your password:</p>
    <p><?= Html::a(Html::encode($resetLink), $resetLink) ?></p>
</div>

And the view for text version /mail/passwordResetToken-text.php:

<?php
$resetLink = Yii::$app->urlManager->createAbsoluteUrl(['site/reset-password', 'token' => $user->password_reset_token]);
?>
Hello <?= $user->username ?>,
Follow the link below to reset your password:
<?= $resetLink ?>

Model indicate as sender of e-mail from the parameter supportEmail, it must also be added. To do this, open the file /config/params.php for editing and add the element supportEmail to the array, you will end up with the following:

<?php

return [
    'adminEmail' => 'admin@devreadwrite.com',
    'user.passwordResetTokenExpire' => 3600,
    'supportEmail' => 'robot@devreadwrite.com'
];

Next, the model for the form of password change /models/ResetPasswordForm.php with the following content:

<?php

namespace app\models;

use yii\base\Model;
use yii\base\InvalidParamException;

/**
 * Password reset form
 */
class ResetPasswordForm extends Model
{

    public $password;

    /**
     * @var \app\models\User
     */
    private $_user;

    /**
     * Creates a form model given a token.
     *
     * @param string $token
     * @param array $config name-value pairs that will be used to initialize the object properties
     * @throws \yii\base\InvalidParamException if token is empty or not valid
     */
    public function __construct($token, $config = [])
    {
        if (empty($token) || !is_string($token)) {
            throw new InvalidParamException('Password reset token cannot be blank.');
        }

        $this->_user = User::findByPasswordResetToken($token);

        if (!$this->_user) {
            throw new InvalidParamException('Wrong password reset token.');
        }

        parent::__construct($config);
    }

    /**
     * @inheritdoc
     */
    public function rules()
    {
        return [
            ['password', 'required'],
            ['password', 'string', 'min' => 6],
        ];
    }

    /**
     * Resets password.
     *
     * @return bool if password was reset.
     */
    public function resetPassword()
    {
        $user = $this->_user;
        $user->setPassword($this->password);
        $user->removePasswordResetToken();
        return $user->save(false);
    }

}

Now we add actions to work with the models described above. Open the controller /controllers/SiteController.php in use add the created models and 2 actions (actionRequestPasswordReset and actionResetPassword):

<?php

namespace app\controllers;

//...

use app\models\SignupForm;
use app\models\PasswordResetRequestForm;
use app\models\ResetPasswordForm;

class SiteController extends Controller
{

    //...

    /**
     * Requests password reset.
     *
     * @return mixed
     */
    public function actionRequestPasswordReset()
    {
        $model = new PasswordResetRequestForm();

        if ($model->load(Yii::$app->request->post()) && $model->validate()) {

            if ($model->sendEmail()) {
                Yii::$app->session->setFlash('success', 'Check your email for further instructions.');
                return $this->goHome();
            } else {
                Yii::$app->session->setFlash('error', 'Sorry, we are unable to reset password for email provided.');
            }

        }

        return $this->render('requestPasswordResetToken', [
            'model' => $model,
        ]);
    }

    /**
     * Resets password.
     *
     * @param string $token
     * @return mixed
     * @throws BadRequestHttpException
     */
    public function actionResetPassword($token)
    {
        try {
            $model = new ResetPasswordForm($token);
        } catch (InvalidParamException $e) {
            throw new BadRequestHttpException($e->getMessage());
        }

        if ($model->load(Yii::$app->request->post()) && $model->validate() && $model->resetPassword()) {
            Yii::$app->session->setFlash('success', 'New password was saved.');
            return $this->goHome();
        }

        return $this->render('resetPassword', [
            'model' => $model,
      }

}

Next, for these two actions, you need to add views, start with the request form to change the password /views/site/passwordResetRequestForm.php:

<?php

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

$this->title = 'Request password reset';
$this->params['breadcrumbs'][] = $this->title;
?>

<div class="site-request-password-reset">
    <h1><?= Html::encode($this->title) ?></h1>
    <p>Please fill out your email. A link to reset password will be sent there.</p>
    <div class="row">
        <div class="col-lg-5">

            <?php $form = ActiveForm::begin(['id' => 'request-password-reset-form']); ?>
                <?= $form->field($model, 'email')->textInput(['autofocus' => true]) ?>
                <div class="form-group">
                    <?= Html::submitButton('Send', ['class' => 'btn btn-primary']) ?>
                </div>
            <?php ActiveForm::end(); ?>

        </div>
    </div>
</div>

And the view for the password change form /views/site/resetPasswordForm.php:

<?php

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

$this->title = 'Reset password';
$this->params['breadcrumbs'][] = $this->title;
?>

<div class="site-reset-password">
    <h1><?= Html::encode($this->title) ?></h1>
    <p>Please choose your new password:</p>
    <div class="row">
        <div class="col-lg-5">

            <?php $form = ActiveForm::begin(['id' => 'reset-password-form']); ?>
                <?= $form->field($model, 'password')->passwordInput(['autofocus' => true]) ?>
                <div class="form-group">
                    <?= Html::submitButton('Save', ['class' => 'btn btn-primary']) ?>
                </div>
            <?php ActiveForm::end(); ?>

        </div>
    </div>
</div>

The final touch, add a link to reset the password in the authorization form view, to do this, open the file /views/site/login.php add a link to reset password:

<div>
    If you forgot your password you can <?= Html::a('reset it', ['site/request-password-reset']) ?>.
</div>

As a result, the view of authorization on the site will look like this:

<?php

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

$this->title = 'Login';
$this->params['breadcrumbs'][] = $this->title;
?>

<div class="site-login">
    <h1><?= Html::encode($this->title) ?></h1>
    <p>Please fill out the following fields to login:</p>

    <?php $form = ActiveForm::begin([
        'id' => 'login-form',
        'layout' => 'horizontal',
        'fieldConfig' => [
            'template' => "{label}\n<div class=\"col-lg-3\">{input}</div>\n<div class=\"col-lg-8\">{error}</div>",
            'labelOptions' => ['class' => 'col-lg-1 control-label'],
        ],
    ]); ?>
        <?= $form->field($model, 'username')->textInput(['autofocus' => true]) ?>
        <?= $form->field($model, 'password')->passwordInput() ?>
        <?= $form->field($model, 'rememberMe')->checkbox([
            'template' => "<div class=\"col-lg-offset-1 col-lg-3\">{input} {label}</div>\n<div class=\"col-lg-8\">{error}</div>",
        ]) ?>
        <div style="color:#999;margin:1em 0">
            If you forgot your password you can <?= Html::a('reset it', ['site/request-password-reset']) ?>.
        </div>
        <div class="form-group">
            <div class="col-lg-offset-1 col-lg-11">
                <?= Html::submitButton('Login', ['class' => 'btn btn-primary', 'name' => 'login-button']) ?>
            </div>
        </div>
    <?php ActiveForm::end(); ?>

</div>

As a result, we got a full functionality of authorization through the database, registration and reset of password in Yii2 basic using the functionality of the template of Yii2 advanced.

Authorization in Yii2 by e-mail instead of username

For authorization on the site, I prefer using the user's e-mail as a login instead of a nickname, by default, yii2 uses a nickname as the login. To fix this is quite simple.

Let's start with the /models/User.php model and add the findByEmail method to search for the user by e-mail:

public static function findByEmail($email)
{
    return static::findOne(['email' => $email, 'status' => self::STATUS_ACTIVE]);
}

Next, in the model /models/LoginForm.php change the $username property to $email in the rules method, add e-mail handling of rule [['email'], 'email'] and in the getUser () method, change the User::findByUsername($this->username) to User::findByEmail($this->email), this is what you get:

<?php

namespace app\models;

use Yii;
use yii\base\Model;

/**
 * LoginForm is the model behind the login form.
 *
 * @property User|null $user This property is read-only.
 *
 */
class LoginForm extends Model
{
    public $email;
    public $password;
    public $rememberMe = true;
    private $_user = false;

    /**
     * @return array the validation rules.
     */
    public function rules()
    {
        return [
            // username and password are both required
            [['email', 'password'], 'required'],
            [['email'], 'email'],
            // rememberMe must be a boolean value
            ['rememberMe', 'boolean'],
            // password is validated by validatePassword()
            ['password', 'validatePassword'],
        ];
    }

    /**
     * Validates the password.
     * This method serves as the inline validation for password.
     *
     * @param string $attribute the attribute currently being validated
     * @param array $params the additional name-value pairs given in the rule
     */
    public function validatePassword($attribute, $params)
    {

        if (!$this->hasErrors()) {

            $user = $this->getUser();

            if (!$user || !$user->validatePassword($this->password)) {
                $this->addError($attribute, 'Incorrect username or password.');
            }

        }

    }

    /**
     * Logs in a user using the provided username and password.
     * @return bool whether the user is logged in successfully
     */
    public function login()
    {
        if ($this->validate()) {
            return Yii::$app->user->login($this->getUser(), $this->rememberMe ? 3600*24*30 : 0);
        }
        return false;
    }

    /**
     * Finds user by [[email]]
     *
     * @return User|null
     */
    public function getUser()
    {
        if ($this->_user === false) {
            $this->_user = User::findByEmail($this->email);
        }
        return $this->_user;
    }

}

Finally, in the /views/site/login.php view, change the username field to email:

<?= $form->field($model, 'email')->textInput(['autofocus' => true]) ?>

All source code is available on github: https://github.com/egor/yii2-basic-auth-through-db.

Article source: https://кодер.укр/записи/yii2-basic-авторизация-и-регистрация-через-бд.