[Serializer] Call to a normalize() function on SerializerInterface in PropertyNormalizer

[Gasol]

I encounter the problem as following error message. Apparently, SerializerInterface does not have normalize function. It must be mistake here.

PHP Fatal error:  Call to a member function normalize() on a non-object in 
/path/to/project/vendor/symfony/serializer/Symfony/Component/Serializer/Normalizer/PropertyNormalizer.php 
on line 71

https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Serializer/Normalizer/PropertyNormalizer.php#L71

[Gasol]

Symfony\Component\Serializer\SerializerInterface does not have normalize function, But Symfony\Component\Serializer\Serializer does.

https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Serializer/Normalizer/ObjectNormalizer.php#L108

<?php
if (!$this->serializer instanceof NormalizerInterface) {
    throw new LogicException(sprintf('Cannot normalize attribute "%s" because injected serializer is not a normalizer', $attribute));
}

So, I think the problem is:

1. Wrong type hinting in setSerializer, should be Symfony\Component\Serializer\Serializer, not Symfony\Component\Serializer\SerializerInterface
2. misuse of SerializerInterface (Obviously, $serializer is not a normalizer)

[dunglas]

@Gasol can you provide the code you made to initialize your serializer and normalizer? Is your Serializer an instance of NormalizerInterface?

1. The typehint is correct. If you don't typehint on the interface, use of custom serializers will be impossible.
2. The default Serializer implements the NormalizerInterface: https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Serializer/Serializer.php#L38

IMO the proper fix is to add a check that the given Serializer implements NormalizerInterface in PropertyNormalizer the same way it is done in ObjectNormalizer.