twig json_encode empty json - json

Question

I'm receiving a list of elements from an API. All the elements are well formatted. When I dump one of them using twig, I get the following :
Leg {#2695 ▼
-id: null
#reservation: null
-airportStart: "AIX LES MILLES"
-airplaneType: "Cessna Citation Mustang"
-airportEnd: "ROBINSON"
-startDate: "2015-09-10 20:00:00"
-startHour: "2015-09-10 20:00:00"
-endHour: "2015-09-10 21:00:21"
-durationLeg: "01:21"
#nbPax: "4"
-price: null
-updatedPrice: null
-discountOnLeg: null
-tva: null
-status: null
}
My user must select one of these elements, So what I'm trying to do is to send the encoded json back to the controller, using
{{ element|json_encode }}
Unfortunately, the json is empty. When I try to dump the encoded json using
{{ dump(element|json_encode) }}
all I get is an empty array {};
Any idea why Is there another way to send the selected element datas to a controller function? (These elements are not persisted, each call on the API returns thousands of results)

Answer 1

I'm little late to the party (2 years of lateness), but for any one like me coming from a google research i say : i had the same problem too, and after googling around, i "solved" my problem with the Serializer Component. How? let me show you!
Installation
php composer.phar require symfony/serializer
Entity
<?php
namespace Your\Namespace\Entity;
use Doctrine\ORM\Mapping as ORM;
use Symfony\Component\Serializer\Serializer;
use Symfony\Component\Serializer\Encoder\JsonEncoder;
use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
/**
* Leg
*
* #ORM\Table()
* #ORM\Entity(repositoryClass="Your\Namespace\Entity\LegRepository")
*/
class Leg {
/**
* #var integer
*
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
...
public function serializer()
{
$encoder = new JsonEncoder();
$normalizer = new ObjectNormalizer();
$normalizer->setIgnoredAttributes(array(
'whatever', 'attributes', 'you', 'want', 'to', 'ignore'
));
// The setCircularReferenceLimit() method of this normalizer sets the number
// of times it will serialize the same object
// before considering it a circular reference. Its default value is 1.
$normalizer->setCircularReferenceHandler(function ($object) {
return $object->getName();
});
$serializer = new Serializer(array($normalizer), array($encoder));
return $serializer->serialize($this, 'json');
}
}
Twig
{{ Leg.serializer|raw }}
N.B : this is tested under symfony 2.6