Symfony Serializer of DateTime Response String - symfony

Question

When attempting to perform a doctrine query and serialze it to json (not using JSM, using the symfony serializer) I get the following in the json:
""due":{"timezone":{"name":"Europe/Berlin","transitions":[{"ts":-2147483648,"time":"1901-12-13T20:45:52+0000","offset":3208,"isdst":false,"abbr":"LMT"},{"ts":-2147483648,"time":"1901-12-13T20:45:52+0000","offset":3600,"isdst":false,"abbr":"CET"},{"ts":-1693706400,"time":"1916-04-30T22:00:00+0000","offset":7200,"isdst":true,"abbr":"CEST"},{"ts":-1680483600,"time":"1916-09-30T23:00:00+0000","offset":3600,"isdst":false,"abbr":"CET"},{"ts":-1663455600,"time":"1917-04-16T01:00:00+0000","offset":7200,"isdst":true,"abbr":"CEST"},{"ts":-1650150000,"time":"1917-09-17T01:00:00+0000","offset":3600,"isdst":false,"abbr":"CET"},{"ts":-1632006000,"time":"1918-04-15T01:00:00+0000","offset":7200,"isdst":true,"abbr":"CEST"},{"ts":-1618700400,"time":"1918-09-16T01:00:00+0000","offset":3600,"isdst":false,"abbr":"CET"},{"ts":-938905200,"time":"1940-04-01T01:00:00+0000","offset":7200,"isdst":true,"abbr":"CEST"},{"ts":-857257200,"time":"1942-11-02T01:00:00+0000","offset":3600,"isdst":false,"abbr":"CET"},{"ts":-844556400,"time":"1943-03-29T01:00:00+0000","offset":7200,"isdst":true,"abbr":"CEST"},{"ts":-828226800,"time":"1943-10-04T01:00:00+0000","offset":3600,"isdst":false,"abbr":"CET"},{"ts":-812502000,"time":"1944-04-03T01:00:00+0000","offset":7200,"isdst":true,"abbr":"CEST"},{"ts":-796777200,"time":"1944-10-02T01:00:00+0000","offset":3600,"
When storing the due date, the timezone is saved and there is an additional timezone field stored. Is there a way to pull the date in a specific format or specify the timezone to use when retrieving?
public function blahAction(Request $request)
{
$currentUser = $this->getUser();
$em = $this->getDoctrine()->getManager();
$blahs = $em->getRepository('AppBundle:blah')->findAllByStatus($currentUser,'TODO');
$encoders = array(new XmlEncoder(), new JsonEncoder());
$normalizer = array(new ObjectNormalizer());
$serializer = new Serializer($normalizer, $encoders);
$response = new Response($serializer->serialize($blahs, 'json'));
$response->headers->set('Content-Type', 'application/json');
return $response;
}

Answer 1

You have 2 ways to get RFC3339 Datetime format ...
Option 1:
Add DateTimeNormalizer as normalizer. An example is https://symfony.com/doc/current/components/serializer.html#recursive-denormalization-and-type-safety.
Change
$normalizer = array(new ObjectNormalizer());
by
$normalizer = array(new DateTimeNormalizer(), new ObjectNormalizer());
Option 2
More simple is using "serializer" container service ... your code will look like ...
public function blahAction(Request $request)
{
$currentUser = $this->getUser();
$em = $this->getDoctrine()->getManager();
$blahs = $em->getRepository('AppBundle:blah')->findAllByStatus($currentUser,'TODO');
$response = new Response($this->get('serializer')->serialize($blahs, 'json'));
$response->headers->set('Content-Type', 'application/json');
return $response;
}
.. or, if your prefer autowiring way (this code is unchecked)
public function blahAction(Request $request, \Symfony\Component\Serializer\SerializerInterface $serializer)
{
$currentUser = $this->getUser();
$em = $this->getDoctrine()->getManager();
$blahs = $em->getRepository('AppBundle:blah')->findAllByStatus($currentUser,'TODO');
$response = new Response($serializer->serialize($blahs, 'json'));
$response->headers->set('Content-Type', 'application/json');
return $response;
}

Answer 2

In Symfony 5.1 it's recomended to add a callback function to specify datetime field format.For example:
use Symfony\Component\Serializer\Serializer;
use Symfony\Component\Serializer\Encoder\JsonEncoder;
use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
use Symfony\Component\Serializer\Normalizer\AbstractNormalizer;
$dateCallback = function ($innerObject, $outerObject, string $attributeName, string $format = null, array $context = []) {
return $innerObject instanceof \DateTime ? $innerObject->format(\DateTime::ISO8601) : '';
};
$defaultContext = [
AbstractNormalizer::CALLBACKS => [
'created_at' => $dateCallback,
'updated_at' => $dateCallback
],
AbstractNormalizer::CIRCULAR_REFERENCE_HANDLER =>
function ($articles, $format, $context) {
return $articles->getId();
}
];
$encoders = [new JsonEncoder()];
$normalizers = [
new ObjectNormalizer(null, null, null,
null, null, null,
$defaultContext)
];
$serializer = new Serializer(
$normalizers, $encoders
);
$articles = $serializer->serialize($articles, 'json');
Where $articles = array of App\Entity\Article objects
You can specify datetime format you need in your callback function.

Answer 3

Another option is to pass arguments to the default DateTimeNormalizer in services.yaml:
Symfony\Component\Serializer\Normalizer\DateTimeNormalizer:
arguments:
$defaultContext:
datetime_format: 'Y-m-d\TH:i:s.v\Z'