gistfile1.txt

 public function behaviors()
    {
        return [
            [
                'class' => TimestampBehavior::className(),
                'attributes' => [
                    ActiveRecord::EVENT_BEFORE_INSERT => ['created_at', 'updated_at'],
                    ActiveRecord::EVENT_BEFORE_UPDATE => ['updated_at'],
                ],
                // if you're using datetime instead of UNIX timestamp:
                // 'value' => new Expression('NOW()'),
            ],
        ];
    }

use yii\behaviors\BlameableBehavior;
use yii\behaviors\SluggableBehavior;
use yii\behaviors\TimestampBehavior;
use yii\db\Expression;

public function behaviors()
    {
        return [
            [
                'class' => TimestampBehavior::className(),
                'value' => new Expression('NOW()'),
            ],
            [
                'class' => BlameableBehavior::className(),
            ],
            [
                'class' => SluggableBehavior::className(),
                'attribute' => 'title',
            ],
        ];
    }