**Course Title:** Mastering Yii Framework: Building Scalable Web Applications **Section Title:** Database Management with Active Record **Topic:** Create models and perform CRUD operations on a database-driven application (e.g., a basic blog system).(Lab topic) **Objective:** By the end of this topic, you will be able to create models and perform CRUD (Create, Read, Update, Delete) operations on a database-driven application using Yii's Active Record component. **Prerequisites:** * You have a basic understanding of the Yii framework and its ecosystem. * You have set up a Yii development environment (Composer, PHP, and Yii installer). * You have explored Yii's directory structure and configuration files. * You have a basic understanding of the MVC (Model-View-Controller) architecture. * You have introduced to routing in Yii (URL management). * You have created and managed controllers. * You have built views with Yii's templating system (PHP-based). * You have passed data between controllers and views. * You have introduced to Yii's database components. * You have used Active Record for database interactions. * You have performed CRUD operations using Active Record. * You have understood relations in Active Record (one-to-one, one-to-many, many-to-many). **Step 1: Create a Model** A model in Yii represents a database table. To create a model, you need to create a PHP class that extends the `yii\db\ActiveRecord` class. ```php // models/Blog.php namespace app\models; use yii\db\ActiveRecord; class Blog extends ActiveRecord { public static function tableName() { return 'blogs'; } } ``` In the above code, we have created a `Blog` model that extends the `ActiveRecord` class. The `tableName()` method returns the name of the database table that this model represents. **Step 2: Create a Migration** To create a migration, you need to run the following command in your terminal: ```bash yii migrate/create create_table_blogs ``` This will create a new migration file in the `migrations` directory. ```php // migrations/m190701_000000_create_table_blogs.php use yii\db\Migration; class m190701_000000_create_table_blogs extends Migration { public function up() { $this->createTable('blogs', [ 'id' => $this->primaryKey(), 'title' => $this->string(), 'title' => $this->string(), 'content' => $this->text(), ]); } public function down() { $this->dropTable('blogs'); } } ``` In the above code, we have created a migration that creates a `blogs` table with four columns: `id`, `title`, `content`, and `created_at`. **Step 3: Perform CRUD Operations** To perform CRUD operations, you need to use the `find()` method to retrieve data from the database, and the `save()` method to save data to the database. ```php // controllers/BlogController.php namespace app\controllers; use yii\web\Controller; use app\models\Blog; class BlogController extends Controller { public function actionIndex() { $blogs = Blog::find()->all(); return $this->render('index', ['blogs' => $blogs]); } public function actionCreate() { $blog = new Blog(); if ($blog->load(Yii::$app->request->post()) && $blog->save()) { return $this->redirect(['index']); } return $this->render('create', ['blog' => $blog]); } public function actionUpdate($id) { $blog = Blog::findOne($id); if ($blog->load(Yii::$app->request->post()) && $blog->save()) { return $this->redirect(['index']); } return $this->render('update', ['blog' => $blog]); } public function actionDelete($id) { $blog = Blog::findOne($id); $blog->delete(); return $this->redirect(['index']); } } ``` In the above code, we have created a `BlogController` that performs CRUD operations on the `blogs` table. **Conclusion:** In this topic, we have learned how to create models and perform CRUD operations on a database-driven application using Yii's Active Record component. We have created a `Blog` model, a migration, and a `BlogController` that performs CRUD operations on the `blogs` table. **Exercise:** Create a new model and a new migration for a `Category` table. Create a new controller that performs CRUD operations on the `categories` table. **Additional Resources:** * Yii Framework Documentation: <https://www.yiiframework.com/doc/> *> * Yii Framework Tutorials: <https://www.yiiframework.com/tutorials*> * Yii Framework Forum: <https://www.yiiframework.com/forum*> **Leave a comment or ask for help:** If you have any questions or need help with this topic, please leave a comment below.