Deserialize DateTime in Symfony - symfony

Question

Trying to use the serializer component in Symfony 3.3. I struggle with entities having 'DateTime' members.
My config.yml serializer init:
serializer:
enable_annotations: true
Added this in service.yml:
datetime_method_normalizer:
class: Symfony\Component\Serializer\Normalizer\DateTimeNormalizer
public: false
tags: [serializer.normalizer]
The deserialized code looks like this:
$yml = [...] // It was created by serializer->serialize()
$serializer = $this->get('serializer');
$myObject = $serializer->deserialize($yml, MyObject::class, "yaml");
The error is get is: Expected argument of type "DateTime", "string" given in in vendor/symfony/symfony/src/Symfony/Component/Serializer/Normalizer/AbstractObjectNormalizer.php (line 204)
I think the DateTimeNormalizer::denormalize never gets called. Any idea how to bring it back to life?
Info: DateTimeNormalizer::__constructor() is called.

Answer 1

As DateTime is a nested object, you should use PropertyInfo Component as described here —
https://symfony.com/doc/current/components/serializer.html#recursive-denormalization-and-type-safety
The extraction of property information is performed by extractor
classes.
https://symfony.com/doc/current/components/property_info.html#extractors
There are 4 types of extractors:
ReflectionExtractor
PhpDocExtractor
SerializerExtractor
DoctrineExtractor
For example, using ReflectionExtractor you need to specify type hint for either params or return type. It also looks for constructor params (requires to be enabled explicitly)
class Item {
protected $date;
public function setDate(\DateTime $date) {...}
public function getDate() : \DateTime {...}
}
Property Info is registered automatically when option set:
# config/packages/framework.yaml
framework:
property_info: ~
After that you need to override serializer service to use it, or define a custom one. And the last part — add DateTimeNormalizer, so DateTime can be processed by serializer.
app.normalizer.item_normalizer:
class: Symfony\Component\Serializer\Normalizer\ObjectNormalizer
arguments:
- null
- null
- null
- '#property_info.reflection_extractor'
tags: [ 'serializer.normalizer' ]
app.serializer.item:
class: Symfony\Component\Serializer\Serializer
public: true
arguments:
- [
'#serializer.normalizer.datetime',
'#app.normalizer.item_normalizer',
]
- [ '#serializer.encoder.json' ]
That's it.

Answer 2

This question break my brain recently, and I've two entities with dateTime property, the solution is custom denormalizer like this:
<?php
namespace MyBundle\Serializer\Normalizer;
use MyBundle\Entity\MyEntity1;
use MyBundle\Entity\MyEntity2;
use Symfony\Component\Serializer\Normalizer\DenormalizerInterface;
use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
/**
* DateTime hook normalizer
*/
class DateTimeHookNormalizer implements DenormalizerInterface
{
/**
* {#inheritdoc}
*/
public function denormalize($data, $class, $format = null, array $context = array())
{
if (isset($data['MyDateTime1']) && is_string($data['MyDateTime1']))
{
$data['MyDateTime1'] = new \DateTime($data['MyDateTime1']);
}
if (isset($data['MyDateTime2']) && is_string($data['MyDateTime2']))
{
$data['MyDateTime2'] = new \DateTime($data['MyDateTime2']);
}
And more ...
$normalizer = new ObjectNormalizer();//default normalizer
return $normalizer->denormalize($data, $class, $format, $context);
}
}
/**
* {#inheritdoc}
*/
public function supportsDenormalization($data, $type, $format = null)
{
return is_array($data) && ($type === MyEntity1::class || $type === MyEntity2::class);
}
And declare service like this :
# DateTime Hook Normalizer
Mybundle.normalizer.dateTimeHook:
class: 'MybundleBundle\Serializer\Normalizer\DateTimeHookNormalizer'
public: false
tags: [serializer.normalizer]
It's ok for me, that work !

Answer 3

The only official way is seems to declare a callback:
$callback = function ($dateTime) {
return $dateTime instanceof \DateTime
? $dateTime->format(\DateTime::ISO8601)
: '';
};
$normalizer->setCallbacks(array('createdAt' => $callback));
$serializer = new Serializer(array($normalizer), array($encoder));
https://symfony.com/doc/current/components/serializer.html#using-callbacks-to-serialize-properties-with-object-instances