Packson

Packson is a json (de)serializer for python3 objects. It uses annotations in the style of jackson.

install:

pip install https://tracinsy.ewi.tudelft.nl/pubtrac/Utilities/export/135/packson/dist/packson-1.0.0.tar.gz

The basic version determines the types for (de)serialization from the init function in the involved classes. Polymorphism is supported, so derived classes can (de)serialized from a superclass.

A complex example showing many things at once (I did not have time to write out many simpler examples)

from jackson.ObjectMapper import ObjectMapper
from jackson.JsonSubTypes import JsonSubTypes
from jackson.JsonTypeInfo import JsonTypeInfo
from jackson.JsonTypeInfo import Id,As
from typing import Dict,List,Set
import json

class Props:
    '''
    compound class with properties, used for testing 
    '''
    def __init__(self, age:int, name:str):
        if age<0:
            raise ValueError("age must be >0, got "+str(age))
        self._age=age
        self._name=name;
    def __str__(self):
        return self._name+","+str(self._age)
    def getage(self):
        return self._age
    def getname(self):
        return self._name
    def __eq__(self, other):
        return isinstance(other, self.__class__) and \
            self._name==other._name and self._age==other._age


@JsonSubTypes(["test.ObjectMapperTest.Bear"])
@JsonTypeInfo(use=Id.NAME, include=As.WRAPPER_OBJECT)
class Animal:
    pass
    
    
class Bear(Animal):
    def __init__(self, props:Props):
        self._props=props
            
    def __str__(self):
        return "Bear["+str(self._props)+"]"
        
    def getprops(self):
        return self._props
    def __eq__(self, other):
        return isinstance(other, self.__class__) and \
            self._props==other._props

jackson=ObjectMapper()


obj=Bear(Props(1,'bruno'))
res=jackson.toJson(obj)
print("result:"+str(res))
bson={'Bear': {'props': {'age': 1, 'name': 'bruno'}}}
res=jackson.parse(bson, Animal)
print("Deserialized an Animal! -->"+str(res))