JMSSerializer stand alone - Annotation does not exist, or cannot be auto-loaded

Question

I am attempting to use JMSSerializer as a stand alone library to map JSON responses from an API to my model classes and am running into some issues.

Executing the following code results in an exception:

<?php
require dirname(__DIR__) . '/vendor/autoload.php';

use JMS\Serializer\Annotation AS JMS;

class Trii {
    /**
     * User ID for this session
     * @JMS\SerializedName("userID")
     * @JMS\Annotation(getter="getUserId")
     * @JMS\Type("string")
     * @var string
     */
    private $userId;

    public function getUserId() {
        return $this->userId;
    }

    public function setUserId($userId) {
        $this->userId = $userId;
    }
}

$serializer = \JMS\Serializer\SerializerBuilder::create()->setDebug(true)->build();
$object = $serializer->deserialize('{"userID":"Trii"}', 'Trii', 'json');
var_dump($object);
?>

Here is the exception

Doctrine\Common\Annotations\AnnotationException: [Semantical Error] The annotation "@JMS\Serializer\Annotation\SerializedName" in property Trii::$userId does not exist, or could not be auto-loaded.

I have the following libraries installed for the project via composer

{
    "require": {
        "jms/serializer": "1.0.*@dev"
    }
}

Is there something obvious I am missing since I am not using the whole Doctrine 2 solution?

EDIT: my final solution was to create a bootstrap file with the following content:

<?php
// standard composer install vendor autoload magic
require dirname(__DIR__) . '/vendor/autoload.php';

// Bootstrap the JMS custom annotations for Object to Json mapping
\Doctrine\Common\Annotations\AnnotationRegistry::registerAutoloadNamespace(
    'JMS\Serializer\Annotation',
    dirname(__DIR__).'/vendor/jms/serializer/src'
);
?>

Answer 1

Pretty sure this enables silent auto-loading which is much more convenient than registering the namespaces yourself.

AnnotationRegistry::registerLoader('class_exists');