YII框架的行为是什么？YII框架如何使用行为？

yii\base\Behavior

events()

// behaviors/LoggerBehavior.php
namespace app\behaviors;

use yii\base\Behavior;
use yii\db\ActiveRecord;
use yii\base\Event;

class LoggerBehavior extends Behavior
{
    public $logCategory = 'application';

    public function events()
    {
        return [
            ActiveRecord::EVENT_AFTER_INSERT => 'logAfterInsert',
            ActiveRecord::EVENT_AFTER_UPDATE => 'logAfterUpdate',
        ];
    }

    public function logAfterInsert(Event $event)
    {
        \Yii::info("新记录插入: " . get_class($event->sender) . " ID: " . $event->sender->id, $this->logCategory);
    }

    public function logAfterUpdate(Event $event)
    {
        \Yii::info("记录更新: " . get_class($event->sender) . " ID: " . $event->sender->id, $this->logCategory);
    }

    public function customLogMessage($message)
    {
        \Yii::info($message, $this->logCategory);
    }
}

behaviors()

// models/Product.php
namespace app\models;

use yii\db\ActiveRecord;
use app\behaviors\LoggerBehavior;

class Product extends ActiveRecord
{
    public static function tableName()
    {
        return 'product';
    }

    public function behaviors()
    {
        return [
            'logger' => [ // 行为的名称，可以是任意字符串
                'class' => LoggerBehavior::class,
                'logCategory' => 'product_activity', // 配置行为的属性
            ],
            // 也可以附加其他行为
            // 'timestamp' => [
            //     'class' => \yii\behaviors\TimestampBehavior::class,
            // ],
        ];
    }

    // ... 其他方法
}

$product = new Product();
// ... 设置 $product 属性
$product->save(); // 会触发 LoggerBehavior 的 logAfterInsert

$product->customLogMessage("产品保存成功，额外信息。"); // 直接调用行为方法

Cat

Animal

Product

Product

ActiveRecord

EVENT_BEFORE_INSERT

EVENT_AFTER_UPDATE

Controller

EVENT_BEFORE_ACTION

events()

events()

SeoBehavior

Controller::EVENT_AFTER_ACTION

AccessControlBehavior

Controller::EVENT_BEFORE_ACTION

// behaviors/SeoBehavior.php
namespace app\behaviors;

use yii\base\Behavior;
use yii\web\Controller;
use yii\base\ActionEvent; // 注意这里是 ActionEvent，因为我们关心action

class SeoBehavior extends Behavior
{
    public function events()
    {
        return [
            Controller::EVENT_AFTER_ACTION => 'setSeoMeta',
        ];
    }

    public function setSeoMeta(ActionEvent $event)
    {
        // 假设这里根据当前action和model数据动态生成SEO信息
        $controller = $event->sender; // 获取触发事件的控制器
        $view = $controller->getView();

        // 简单示例：根据控制器ID和Action ID设置标题
        $view->title = ucfirst($controller->id) . ' - ' . ucfirst($event->action->id);

        // 实际中可能还会设置keywords, description等
        $view->registerMetaTag(['name' => 'keywords', 'content' => 'Yii, Behavior, SEO']);
        $view->registerMetaTag(['name' => 'description', 'content' => 'Yii框架行为与SEO的结合应用。']);
    }
}

// controllers/ProductController.php
namespace app\controllers;

use yii\web\Controller;
use app\behaviors\SeoBehavior;

class ProductController extends Controller
{
    public function behaviors()
    {
        return [
            'seo' => [
                'class' => SeoBehavior::class,
            ],
        ];
    }

    public function actionView($id)
    {
        // ... 获取产品数据并渲染视图
        return $this->render('view', ['model' => $product]);
    }
}

ProductController

SeoBehavior

setSeoMeta

behaviors()

// models/User.php
namespace app\models;

use yii\db\ActiveRecord;
use yii\behaviors\TimestampBehavior;
use yii\behaviors\BlameableBehavior; // 假设有一个记录操作者的行为

class User extends ActiveRecord
{
    public function behaviors()
    {
        return [
            [ // 无名称的行为，Yii会自动生成一个
                'class' => TimestampBehavior::class,
                'createdAtAttribute' => 'created_at',
                'updatedAtAttribute' => 'updated_at',
                'value' => new \yii\db\Expression('NOW()'),
            ],
            'blameable' => [ // 有名称的行为，方便后续通过名称访问
                'class' => BlameableBehavior::class,
                'createdByAttribute' => 'created_by',
                'updatedByAttribute' => 'updated_by',
            ],
        ];
    }
    // ...
}

attachBehavior()

attachBehaviors()

use yii\base\Component;
use app\behaviors\LoggerBehavior;

$myComponent = new Component();

// 动态附加单个行为
$myComponent->attachBehavior('dynamicLogger', [
    'class' => LoggerBehavior::class,
    'logCategory' => 'dynamic_logs',
]);

// 现在可以通过 $myComponent 访问 LoggerBehavior 的方法
$myComponent->customLogMessage("这是通过动态附加的行为记录的消息。");

// 动态附加多个行为
$anotherComponent = new Component();
$anotherComponent->attachBehaviors([
    'behaviorA' => ['class' => 'app\behaviors\BehaviorA'],
    'behaviorB' => ['class' => 'app\behaviors\BehaviorB'],
]);

// 也可以在需要时移除行为
$myComponent->detachBehavior('dynamicLogger');

ActiveRecord