YII2 add user->identity variable

class User extends ActiveRecord implements \yii\web\IdentityInterface
{
    // Other code goes here...
    public function getFullname()
    {
        $profile = Profile::find()->where(['user_id'=>$this->id])->one();
        if ($profile !==null)
            return $profile->fullname;
        return false;
    }
}

Yii::$app->user->identity->fullname;