Learn YII with Real Code Examples

<?php

// controllers/CounterController.php
namespace app\controllers;
use Yii;
use yii\web\Controller;

class CounterController extends Controller {
    public function actionIndex() {
        $session = Yii::$app->session;
        if (!$session->has('count')) { $session->set('count', 0); }
        $count = $session->get('count');
        return $this->render('index', ['count' => $count]);
    }

    public function actionIncrement() {
        $session = Yii::$app->session;
        $session->set('count', $session->get('count', 0) + 1);
        return $this->redirect(['index']);
    }

    public function actionDecrement() {
        $session = Yii::$app->session;
        $session->set('count', $session->get('count', 0) - 1);
        return $this->redirect(['index']);
    }

    public function actionReset() {
        Yii::$app->session->set('count', 0);
        return $this->redirect(['index']);
    }
}

// views/counter/index.php
<h2>Counter: <?= $count ?></h2>
<form method='post' action='increment'><button type='submit'>+</button></form>
<form method='post' action='decrement'><button type='submit'>-</button></form>
<form method='post' action='reset'><button type='submit'>Reset</button></form>

Demonstrates a simple Yii controller and view for a counter using session for state persistence.