Weasel is an object marshalling library for PHP supporting JSON and XML. Marshalling is, by default, configured using "annotations", driven by the Doctrine\Common\Annotation library.
It also includes it's own Annotation library, Weasel\Annotation, but this is considered deprecated in favour of using Doctrine.
The latest version can be found here: https://github.com/moodev/php-weasel
The documentation can be found here: https://github.com/moodev/php-weasel/wiki
If you can, use composer. If you can't, you'll find the list of dependencies in composer.json.
Annotate the classes you want to serialize/deserialize (see the documentation.)
Then:
$factory = new WeaselDoctrineAnnotationDrivenFactory();
// optionally:
// $factory->setCache($cacheInstance);
// $factory->setLogger($psr3LoggerInstance);
$mapper = $factory->getJsonMapperInstance();
$thing = $mapper->readString($json, $typeToDecodeTo);
$backToJson = $mapper->writeString($thing);
json_decode() decodes to arrays or stdObj. Weasel, while making use of json_decode() internally, maps to objects; It's basically a configuration driven Object Mapper for JSON.
Meanwhile, json_encode() gives you no fine grained control over how your data gets serialized to JSON. You can't disable marshalling of fields, you can't add typing information without adding it to your classes, and, most annoyingly, you don't have any control over how array() gets mapped on a field-by-field basis. Weasel allows you to configure how fields are marshaled on a per field level: if you've got an array that should always be mapped as a JSON object, while other arrays need to be mapped as an array, you can have just that.
The XmlMarshaller just seemed like a good idea at the time. It probably wasn't. It's incomplete and unloved. As soon as I find a better approach to the problem, it'll be deprecated.
This project spawned from work on moo-php, a client library for the moo.com API. After writing serialization/deserialization code that was specific to that object structure, I realised that a general purpose, configurable, marshaller, similar to Jackson in the Java world, would be rather useful. Weasel is the result.