Yii2 login from database

1. Create users table
   
   CREATE TABLE `users` (
     `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
     `email` varchar(255) DEFAULT NULL,
     `password_hash` varchar(255) DEFAULT NULL,
     PRIMARY KEY (`id`),
     KEY `email` (`email`) USING BTREE
   );
     
2. Create Users Model
   
   
   
   
   While you are at Gii, you should create search model too.
   
   
   
3. Add the following namespaces in Users model class
   
   use yii\base\NotSupportedException;
   use yii\db\ActiveRecord;
   use yii\helpers\Security;
   use yii\web\IdentityInterface;
   
   
4.  Implements the IdentityInterface interface class with Users model class
   
   class Users extends \yii\db\ActiveRecord  implements IdentityInterface
   
   Then add all the inherited functions from yii\web\IdentityInterface. See https://www.yiiframework.com/doc/api/2.0/yii-web-identityinterface
   
   Add function validatePassword in model/Users.php.
   
   /**
        * Validates password
        *
        * @param string $password password to validate
        * @return bool if password provided is valid for current user
        */
   
       public function validatePassword($password)
       {
           return password_verify($password, $this->password_hash);
       }
   
   You can change the code to whatever you use to validate the password.
   
   
5. Assign identityClass in config\web.php
   
   'user' => [
       'identityClass' => 'app\models\Users',
       'enableAutoLogin' => false,
   ],
   
   
6. Modify models\LoginForm to use email as login and Users model. Just do a global replace in models\LoginForm to replace username with email.
   
   For function getUser, change the model to Users and fix the capitalization. And add function findByEmail in models/Users.php.
   
       /**
        * Finds user by email
        *
        * @param  string      $email
        * @return static|null
        */
       public static function findByEmail($email)
       {
           return static::findOne(['email' => $email]);
       }
   
   
   
7. Update views/site/login.php and do global replace to change username to email
   
   
8. Update views/layout/main.php and change 'Logout (' . Yii::$app->user->identity->email . ')' to 'Logout (' . Yii::$app->user->identity->email . ')'. This will update the logout menu to use email field instead of username.

Additional validation (optional):

1. ['email', 'email'] in models/LoginForm
2. ['email', 'email'] and ['email', 'unique'] in model/Users

Completed models\Users.php

<?php
namespace app\models;

use Yii;
use yii\base\NotSupportedException;
use yii\db\ActiveRecord;
use yii\helpers\Security;
use yii\web\IdentityInterface;

/**
 * This is the model class for table "users".
 *
 * @property string $id
 * @property string $email
 * @property string $password_hash
 */
class Users extends \yii\db\ActiveRecord  implements IdentityInterface
{
    /**
     * {@inheritdoc}
     */
    public static function tableName()
    {
        return 'users';
    }

    /**
     * {@inheritdoc}
     */
    public function rules()
    {
        return [
            [['email', 'password_hash'], 'string', 'max' => 255],
            ['email', 'email'],
            ['email', 'unique'],
        ];
    }

    /**
     * {@inheritdoc}
     */
    public function attributeLabels()
    {
        return [
            'id' => 'ID',
            'email' => 'Email',
            'password_hash' => 'Password Hash',
        ];
    }
 
    public static function findIdentity($id)
    {
        return static::findOne($id);
    }

    public static function findIdentityByAccessToken($token, $type = null)
    {
        return static::findOne(['access_token' => $token]);
    }

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

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

    public function validateAuthKey($authKey)
    {
        return $this->authKey === $authKey;
    }
 
    /**
     * Validates password
     *
     * @param string $password password to validate
     * @return bool if password provided is valid for current user
     */

    public function validatePassword($password)
    {
        return password_verify($password, $this->password_hash);
    }

    /**
     * Finds user by email
     *
     * @param  string      $email
     * @return static|null
     */
    public static function findByEmail($email)
    {
        return static::findOne(['email' => $email]);
    }
}

models/LoginForm.php

<?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 [
            // email and password are both required
            [['email', 'password'], 'required'],
            // rememberMe must be a boolean value
            ['rememberMe', 'boolean'],
            // password is validated by validatePassword()
            ['password', 'validatePassword'],
            ['email', 'email'],
        ];
    }

    /**
     * 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 email or password.');
            }
        }
    }

    /**
     * Logs in a user using the provided email 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) {
            $this->_user = Users::findByEmail($this->email);
        }

        return $this->_user;
    }
}

Credit: https://www.compromath.com/code-formatting-syntax-highlighter-for-blogger