使用Phalcon过滤器时得到未定义的变量？

Question

I am unclear here! I got error Notice: Undefined variable: filter when running below code!

But when I remove declare public $filter line,It worked !!! Why ?

use Phalcon\Filter;

class Auth extends Component {   
    public $filter;//remove this line is working
    public function initialize() {
        $this->db = $this->getDI()->getShared("db");
        $this->login_db = $this->getDI()->getShared("login_db");
        $this->filter = new Filter();
    }
    public function auth($name) {
    $name = $this->filter->sanitize($name,"string");
    }

    }

Answer 1

I made a simple test and reproduced the issue. Let me explain what happens here.

1. auth($name) is a constructor for the Auth class. Yes, this is old constructor style . This method is called when the object is created. initialize() is not called before the object is created and thus the code $this->filter = new Filter(); is not called before auth() method.

2. If you comment out declaration public $filter and access the property in constructor then the magic __get() method is invoked from parent class \\Phalcon\\Di\\Injectable and the property is taken from DI container . This is why no errors are shown.

3. If you specify the property public $filter and create the object the constructor ( auth() method) is called before initialize() method and thus property is only defined but not initialized. In this case you get the error.

Fatal error: Call to a member function sanitize() on a non-object in /var/www/app/models/Auth.php on line 19

Let me know if you have any questions.