Quickstart

Here are the supported features that Dataclass Wizard currently provides:

• JSON (de)serialization: marshal dataclasses to/from JSON and Python dict objects.

• Field properties: support for using properties with default values in dataclass instances.

The below is an quick demo of both of these features - how to marshal dataclasses to/from JSON and Python dict objects, and declare and use field properties with default values.

from dataclasses import dataclass, field
from datetime import datetime
from typing import Optional, List

from dataclass_wizard import JSONSerializable, property_wizard


@dataclass
class MyClass(JSONSerializable, metaclass=property_wizard):

    my_str: Optional[str]
    list_of_int: List[int] = field(default_factory=list)
    # You can also define this as `my_dt`, however only the annotation
    # will carry over in that case, since the value is re-declared by
    # the property below. See also the 'Using Field Properties' section
    # in the docs for a more elegant approach.
    _my_dt: datetime = datetime(2000, 1, 1)

    @property
    def my_dt(self):
        """
        A sample `getter` which returns the datetime with year set as 2010
        """
        if self._my_dt is not None:
            return self._my_dt.replace(year=2010)
        return self._my_dt

    @my_dt.setter
    def my_dt(self, new_dt: datetime):
        """
        A sample `setter` which sets the inverse (roughly) of the `month` and `day`
        """
        self._my_dt = new_dt.replace(
            month=13 - new_dt.month,
            day=31 - new_dt.day)


string = '''{"myStr": 42, "listOFInt": [1, "2", 3]}'''
# Uses the default value for `my_dt`, with year=2000, month=1, day=1
c = MyClass.from_json(string)

print(repr(c))
# prints:
#   MyClass(my_str='42', list_of_int=[1, 2, 3], my_dt=datetime.datetime(2010, 12, 30, 0, 0))

my_dict = {'My_Str': 'string', 'myDT': '2021-01-20T15:55:30Z'}
c = MyClass.from_dict(my_dict)

print(repr(c))
# prints:
#   MyClass(my_str='string', list_of_int=[], my_dt=datetime.datetime(2010, 12, 11, 15, 55, 30, tzinfo=datetime.timezone.utc))

print(c.to_json())
# prints:
#   {"myStr": "string", "listOfInt": [], "myDt": "2010-12-11T15:55:30Z"}