Complete steps to use yii3 loging using di

Yii 3.0
1

Hi,

Can any one provide complete steps to add logging in yii3 using di and Psr\Log\LoggerInterface

Thanks,

2

1: Install Logger (Monolog)
Yii3 uses PSR-3, so we install Monolog:

composer require monolog/monolog

2: Configure Logger in DI Container

Open your DI config (usually):

config/common/di.php

Add this:


use Psr\Log\LoggerInterface;
use Monolog\Logger;
use Monolog\Handler\StreamHandler;

return [
    LoggerInterface::class => function () {
        $logger = new Logger('app');

        // logs will be saved in runtime/logs/app.log
        $logger->pushHandler(
            new StreamHandler(__DIR__ . '/../../runtime/logs/app.log', Logger::DEBUG)
        );

        return $logger;
    },
];

3: Use Logger in Controller / Service

Now you can inject logger anywhere using DI:

use Psr\Log\LoggerInterface;

class SiteController
{
    private $logger;

    public function __construct(LoggerInterface $logger)
    {
        $this->logger = $logger;
    }

    public function actionIndex()
    {
        $this->logger->info('This is info log');
        $this->logger->error('Something went wrong');

        echo "Check log file!";
    }
}

4: Log File Location

After running, check:
runtime/logs/app.log
You’ll see logs like:

[2026-04-09] app.INFO: This is info log
[2026-04-09] app.ERROR: Something went wrong

5: Different Log Types (Easy)

$this->logger->debug(‘Debug message’);
$this->logger->info(‘Info message’);
$this->logger->warning(‘Warning message’);
$this->logger->error(‘Error message’);
$this->logger->critical(‘Critical issue’);

3

Step 1: Install Yii3 User/Auth Packages

composer require yiisoft/auth yiisoft/user

Step 2: Create User Model

// User.phpclass User{    private int $id;    private string $username;    private string $password;    public function getId(): int    {        return $this->id;    }    public function getUsername(): string    {        return $this->username;    }    public function getPassword(): string    {        return $this->password;    }}

Step 3: Save Password Hashed

$passwordHash = password_hash('123456', PASSWORD_DEFAULT);

Save $passwordHash in database.

Step 4: Create Login Form

<form method="post" action="/login">    <input type="text" name="username" placeholder="Username">    <input type="password" name="password" placeholder="Password">    <button type="submit">Login</button></form>

Step 5: Create Login Controller

public function login(ServerRequestInterface $request): ResponseInterface{    $data = $request->getParsedBody();    $username = $data['username'];    $password = $data['password'];    $user = $this->userRepository->findByUsername($username);    if ($user && password_verify($password, $user->getPassword())) {        $identity = new Identity(            $user->getId(),            $user->getUsername()        );        $this->auth->login($identity);        return $this->responseFactory            ->createResponse(302)            ->withHeader('Location', '/dashboard');    }    echo "Invalid Login";}

Step 6: Add Route

Route::post('/login', [LoginController::class, 'login']);

Step 7: Test Login

Open:

http://localhost/login

Login with:

username: adminpassword: 123456

Step 8: Logout

$this->auth->logout();

Step 9: Check Logged User

if ($this->auth->isAuthenticated()) {    echo "Logged In";}

Memory almost f