jsonlight 0.0.2

Standard types

This is what you can already do in Python:

from jsonlight import loads, dumps
from uuid import UUID, uuid4

obj = uuid4()
assert obj == UUID(loads(dumps(str(obj))))

All standard Python types such as UUID must have an encode/decode method in the default typemap provided by jsonlight, so encoding to JSON should always work. However, the type must be specified on load:

from jsonlight import loads, dumps
from uuid import UUID, uuid4

obj = uuid4()
assert obj == loads(UUID, dumps(obj))

You can see that the main difference with json.loads is that jsonlight.loads requires a type as first argument. This is because jsonlight.loads will first call json.loads to convert the string into a Python object with basic JSON tyes, and then pass that to the type’s __jsonload__ function.

Nested types

You may leverage the __jsondump__ and __jsonload__ methods based on the following conventions:

• __jsondump__: return a representation of self with JSON data types

• __jsonload__: instanciate an object based on the result from __jsondump__

Example:

from jsonlight import load

class YourClass:
    def __init__(self, uuid=None):
        self.uuid = uuid or uuid4()

    def __jsondump__(self):
        return dict(uuid=self.uuid)

    @classmethod
    def __jsonload__(cls, data):
        return cls(load(UUID, data['uuid'])

        # This also works, but would not illustrate how to support recursion
        # return cls(UUID(data['uuid']))

As you can see:

• you don’t have to worry about calling __jsondump__ on return values of your own __jsondump__ because jsonlight.dumps will do that recursively,

• you have full control on deserialization just like with __setstate__, but if you call jsonlight.load in there yourself then you don’t have to duplicate deserialization logic on nested objects,