ZF2 using PHP5 vs PHP7

Question

I have a problem with my custom class located in:

module/SomeModule/src/SomeModule/Model/someClass.php

I get a database adapter like this using the ServiceLocator (exactly as in this Learning Zend Framework 2 tutorial):

public function getAdapter()
{
  if (!$this->adapter) {
    $sm = $this->getServiceLocator();
    $this->adapter = $sm->get('Zend\Db\Adapter\Adapter');
  }
  return $this->adapter;
}

In PHP 5 it works just fine, but in PHP 7 it doesn't. It seems that the class is no longer ServiceLocatorAware in PHP 7. And gives this error:

Fatal error: Uncaught Error: Using $this when not in object context in C:\Zend9\Apache24\htdocs\Project\module\Account\src\Account\Model\User.php:316 
Stack trace:
#0 C:\Zend9\Apache24\htdocs\Project\module\Account\src\Account\Model\User.php(271): Account\Model\User::getAdapter()
#1 C:\Zend9\Apache24\htdocs\Project\module\Account\src\Account\Controller\LoginController.php(40): Account\Model\User::userLogin('xxx', 'xxx')
#2 C:\Zend9\ZendServer\data\libraries\Zend_Framework_2\2.4.9\library\Zend\Mvc\Controller\AbstractActionController.php(82): Account\Controller\LoginController->indexAction()
#3 [internal function]: Zend\Mvc\Controller\AbstractActionController->onDispatch(Object(Zend\Mvc\MvcEvent))
#4 C:\Zend9\ZendServer\data\libraries\Zend_Framework_2\2.4.9\library\Zend\EventManager\EventManager.php(444): call_user_func(Array, Object(Zend\Mvc\MvcEvent))
#5 C:\Zend9\ZendServer\data\libraries\Zend_Framework_2\2.4.9\library\Zend\EventManager\EventManager.php(205): Zend\EventManager\EventManager->trigg
in C:\Zend9\Apache24\htdocs\Project\module\Account\src\Account\Model\User.php on line 316

Anyone can tell me why there is this difference between PHP 5 and PHP 7 and how to resolve it?

Answer 1

You or the Zend Framework are calling a static member with $this (similiar to calling a non-static member using a static call).

If you didn't remove half of your error message I could tell you where exactly this happens.

From http://php.net/manual/en/language.oop5.basic.php

The pseudo-variable $this is available when a method is called from within an object context. $this is a reference to the calling object (usually the object to which the method belongs, but possibly another object, if the method is called statically from the context of a secondary object). As of PHP 7.0.0 calling a non-static method statically from an incompatible context results in $this being undefined inside the method. Calling a non-static method statically from an incompatible context has been deprecated as of PHP 5.6.0. As of PHP 7.0.0 calling a non-static method statically has been generally deprecated (even if called from a compatible context). Before PHP 5.6.0 such calls already triggered a strict notice.