PhpStorm object reference error object within object

I have this code, which works fine

use path\to\class\exampleClass;
class foo {
  public function preparePortalService() {
    $this->portalService = new exampleClass(array(), $this->getWsdl('portal'));
    $portalservice_header = new \SoapHeader($this->getWsdl('portal'), 'SessionHeader', $header);
    // Set the Session Header.
    $this->portalService->__setSoapHeaders($portalservice_header);
  }
}

in another file (which is being autoloaded successfully

namespace path\to\class\exampleClass;

class exampleClass extends \SoapClient {
  public function __construct(array $options = array(), $wsdl = 'wsdl/Interface.xml')
  {}
}

However, I get a 'Field portalService not found in class foo' warning in PhpStorm (Note: not in the error logs, the code works fine).

Why is this, and how can I get it to recognise the object properties and methods?

EDIT: expanded, sorry for the formatting.

To clarify, the class methods and properties autocompletes are accessible through $portalService in PhpStorm if I do this:

$portalService = new exampleClass(array(), $this->getWsdl('portal'));

But if I do this,

$this->portalService = $portalService;

then PhpStorm tells me it can't find it when I try this

$this->portalService->__setSoapHeaders($portalservice_header);

Solution

PHPStorm is nagging you because although your code will compile and run, it's not well designed. When you try to assign a new value to $this->portalService, the IDE looks around but cannot find any declaration for class property postalService. In short, you are assigning a value to a property that does not exist.

The code still runs because PHP, unlike some other languages, will infer that you intended to declare a class property and assign a value to it, even though you never actually declared it. The better design is to add a declaration:

class foo {
  private $postalService=null; //now you've formally declared the class property

  public function preparePortalService() {
    $this->portalService = ... // no problem. this property exists.
  }
}

You also mentioned that:

$portalService = new exampleClass... doesn't pose a problem

That's correct. On this line, you're not referring to a class property (eg: $this->postalService, but you are creating and setting a local variable.