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18.

Using a Serializer

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We're turning Programmers into JSON by hand inside serializeProgrammer():

158 lines | src/AppBundle/Controller/Api/ProgrammerController.php
// ... lines 1 - 15
class ProgrammerController extends BaseController
{
// ... lines 18 - 147
private function serializeProgrammer(Programmer $programmer)
{
return array(
'nickname' => $programmer->getNickname(),
'avatarNumber' => $programmer->getAvatarNumber(),
'powerLevel' => $programmer->getPowerLevel(),
'tagLine' => $programmer->getTagLine(),
);
}
}

That's pretty ok with just one resource, but this will be a pain when we have a lot more - especially when resources start having relations to other resources. It'll turn into a whole soap opera. To make this way more fun, we'll use a serializer library: code that's really good at turning objects into an array, or JSON or XML.

The one we'll use is called "JMS Serializer" and there's a bundle for it called JMSSerializerBundle. This is a fanstatic library and incredibly powerful. It can get complex in a few cases, but we'll cover those. You should also know that this library is not maintained all that well anymore and you'll see a little bug that we'll have to work around. But it's been around for years, it's really stable and has a lot of users.

Symfony itself ships with a serializer, Symfony 2.7 has a lot of features that JMS Serializer has. There's a push inside Symfony to make it eventually replace JMS Serialize for most use-cases. So, keep an eye on that. Oh, and JMS Serializer is licensed under Apache2, which is a little bit less permissive than MIT, which is Symfony's license. If that worries you, look into it further.

With all that out of the way, let's get to work. Copy the composer require line and paste it into the terminal:

composer require jms/serializer-bundle

While we're waiting, copy the bundle line and add this into our AppKernel:

40 lines | app/AppKernel.php
// ... lines 1 - 5
class AppKernel extends Kernel
{
public function registerBundles()
{
$bundles = array(
// ... lines 11 - 19
new \JMS\SerializerBundle\JMSSerializerBundle(),
);
// ... lines 22 - 31
return $bundles;
}
// ... lines 34 - 40

This gives us a new service calld jms_serializer, which can turn any object into JSON or XML. Not unlike a Harry Potter wizarding spell.... accio JSON! So in the controller, rename serializeProgrammer to serialize and make the argument $data, so you can pass it anything. And inside, just return $this->container->get('jms_serializer') and call serialize() on that, passing it $data and json:

151 lines | src/AppBundle/Controller/Api/ProgrammerController.php
// ... lines 1 - 15
class ProgrammerController extends BaseController
{
// ... lines 18 - 144
private function serialize($data)
{
return $this->container->get('jms_serializer')
->serialize($data, 'json');
}
}

PhpStorm is angry, just because composer hasn't finished downloading yet: we're working ahead.

Find everywhere we used serializeProgrammer() and change those. The only trick is that it's not returning an array anymore, it's returning JSON. So I'll say $json = $this->serialize($programmer). And we can't use JsonResponse anymore, or it'll encode things twice. Create a regular Response instead. Copy this and repeat the same thing in showAction(). Use a normal Response here too:

151 lines | src/AppBundle/Controller/Api/ProgrammerController.php
// ... lines 1 - 21
public function newAction(Request $request)
{
// ... lines 24 - 33
$json = $this->serialize($programmer);
$response = new Response($json, 201);
// ... lines 36 - 39
$response->headers->set('Location', $programmerUrl);
return $response;
}
// ... lines 44 - 48
public function showAction($nickname)
{
// ... lines 51 - 61
$json = $this->serialize($programmer);
$response = new Response($json, 200);
return $response;
}
// ... lines 68 - 151

For listAction, life gets easier. Just put the $programmers array inside the $data array and then pass this big structure into the serialize() function:

151 lines | src/AppBundle/Controller/Api/ProgrammerController.php
// ... lines 1 - 72
public function listAction()
{
$programmers = $this->getDoctrine()
->getRepository('AppBundle:Programmer')
->findAll();
$json = $this->serialize(['programmers' => $programmers]);
$response = new Response($json, 200);
return $response;
}
// ... lines 84 - 151

The serializer has no problem serializing arrays of things. Make the same changes in updateAction():

151 lines | src/AppBundle/Controller/Api/ProgrammerController.php
// ... lines 1 - 88
public function updateAction($nickname, Request $request)
{
// ... lines 91 - 108
$json = $this->serialize($programmer);
$response = new Response($json, 200);
return $response;
}
// ... lines 114 - 151

Great! Let's check on Composer. It's done, so let's try our entire test suite:

phpunit -c app

Ok, things are not going well. One of them says:

Error reading property "avatarNumber" from available keys
(id, nickname, avatar_number, power_level)

The responses on top show the same thing: all our properties are being underscored. The JMS Serializer library does this by default... which I kinda hate. So we're going to turn it off.

The library has something called a "naming strategy" - basically how it transforms property names into JSON or XML keys. You can see some of this inside the bundle's configuration. They have a built-in class for doing nothing: it's called the "identical" naming strategy. Unfortunately, the bundle has a bug that makes this not configurable in the normal way. Instead, we need to go kung-foo on it.

Open up config.yml. I'll paste a big long ugly new parameter here:

79 lines | app/config/config.yml
// ... lines 1 - 5
parameters:
# a hack - should be configurable under jms_serializer, but the property_naming.id
# doesn't seem to be taken into account at all.
jms_serializer.camel_case_naming_strategy.class: JMS\Serializer\Naming\IdenticalPropertyNamingStrategy
// ... lines 10 - 79

This creates a new parameter called jms_serializer.camel_case_naming_strategy.class. I'm setting this to JMS\Serializer\Naming\IdenticalPropertyNamingStrategy. That is a total hack - I only know to do this because I went deep enough into the bundle to find this. If you want to know how this works, check out our Journey to the Center of Symfony: Dependency Injection screencast: it's good nerdy stuff. The important thing for us is that this will leave our property names alone.

So now if we run the test:

phpunit -c app

we still have failures. But in the dumped response, our property names are back!