Factory Pattern in the Real World

If you're as excited as I am about the Factory pattern, you may want to start using it in your Symfony applications. Fortunately, Symfony provides solid support.

Using Factories with Symfony

Check it out! Go to the Symfony docs site, search for "Using Factory", and click on the first link here.

This shows us a ton of ways to use a factory, like creating objects through a "static factory", which is just a static method inside of a service class. And down here, we can see the configuration we need to set this up - by using the factory option in the client definition to specify the factory class and static method to call. Super helpful!

Another option is making the class you want to instantiate its own factory. It also works with a static method, and it's super handy for minimizing the amount of classes we have, all while keeping the instantiation logic in one place. Down here, we also have the "Non-Static Factory", which is pretty similar to what we've been doing. The main difference is that Symfony will take care of instantiating the factory, calling the make() method, and injecting whatever it returns into the service that needs it. Oh, and if your make() method requires some arguments, you can use the arguments option to define them. And if none of these options works for you, you can always inject your factory into your services and call the make() method yourself, just like we did in this tutorial.

Factory in Symfony Forms

Okay, those are some of the options Symfony gives us for using the Factory pattern. But does Symfony use the pattern internally? You bet! Symfony uses the Factory pattern in the Form component.

Let's take a look at the code:

class TaskController extends AbstractController
{
    public function new(Request $request): Response
    {
        $task = new Task();

        $form = $this->createForm(TaskType::class, $task);
        
        $form->handleRequest($request);
        ...
    }
}

This is a simple controller method that receives a request, creates a form object by calling $this->createForm(), and processes it. Now, let's look at the createForm() method.

class AbstractController implements ServiceSubscriberInterface
{
    protected function createForm(string $type, mixed $data = null, array $options = []): FormInterface
    {
        return $this->container->get('form.factory')->create($type, $data, $options);
    }
}

This is a shortcut for fetching the form.factory service from the container and calling create() on it. If you look at the arguments, it receives a $type parameter that determines what form object to create, as well as some data to fill it in. Look familiar? We did this earlier too!

Conclusion

All right! That's the Factory pattern! Let's go over some of the pros and cons:

✅ First, it's a great way to decouple the code that creates objects from the code that uses them. ✅ It's also very helpful when you need to create different families of objects. ✅ And finally, it leverages the SRP and Open-Closed principles.

❌ But, it may make your code base more complex, especially if you have a lot of factories.

Okay, team! We're done! We covered a lot of patterns, but there are still more out there. If there's a pattern that you'd really like to hear about, let us know! Until then, have fun putting all these into practice, and if you need help, we're here for you down in the comments.

Thanks for coding with me, and I'll see you next time!