Non-Static Method Called Statically

Why This Happens

PHP distinguishes between static and instance methods. Static methods are called with :: and do not have access to $this. Instance methods require an object. In PHP 8.0+, calling a non-static method statically throws a fatal error instead of the previous deprecation notice.

The Problem

class UserService {
    public function findAll(): array {
        return $this->repository->findAll();
    }
}
$users = UserService::findAll(); // Not a static method

The Fix

class UserService {
    public function findAll(): array {
        return $this->repository->findAll();
    }
}
$service = new UserService();
$users = $service->findAll();

Step-by-Step Fix

1. 1

   Check the method declaration

   Look at the method definition. If it does not have the static keyword, it is an instance method that requires an object.

2. 2

   Create an instance

   Instantiate the class with new and call the method on the instance using -> instead of ::.

3. 3

   Make static if appropriate

   If the method does not use $this or instance state, add the static keyword to the method declaration.