Description

Feature: [Serializer] DiscrminatorMap: Improved error message

At the moment we get a Serializer Exception when a value is not in the discrminatorMap.

Symfony\Component\Serializer\Normalizer\AbstractObjectNormalizer.php Line: 813

{
	"message": "Serializer exception: The type \"type\" is not a valid value."
}

This was merged after this issue was implemented: PR 43004

The new feature would contain extra information about the allowed values and/or a custom error message.

Example

Proposal

1. Additional information about the allowed values:

Symfony\Component\Serializer\Normalizer\AbstractObjectNormalizer.php Line: 813

$allowedValues = implode(', ', array_keys($mapping->getTypesMapping()))

throw NotNormalizableValueException::createForUnexpectedDataType(sprintf('The type "%s" is not a valid value, allowed values: %s.', $type, $allowedValues), $type, ['string'], isset($context['deserialization_path']) ? $context['deserialization_path'].'.'.$mapping->getTypeProperty() : $mapping->getTypeProperty(), true);

1. A custom error message

I can make a PR if this is found useful.