Pickling an instance of a dataclass

user_7978112 0
Viewed 3100

Is there a possibility to pickle/dill an_instance developed as follows?

import dill
import pandas as pd
import numpy as np
from datetime import datetime, timezone
from dataclasses import make_dataclass, field

fields = [('float_val', float, field(default=np.nan)),
          ('df', pd.DataFrame, field(default_factory=pd.DataFrame)),
          ('int_val', int, field(default_factory=int)),
          ('time_val', datetime, field(default=datetime.now(timezone.utc)))]

Aclass = make_dataclass('Aclass', fields)

an_instance=Aclass()

dill.dump(an_instance, open('test.pkl', 'wb'))

The dump gives PicklingError: Can't pickle <class 'types.Aclass'>: it's not found as types.Aclass

python-dataclasses python
2 Answers

Thx @Tom Myddeltyn for Issue35510 bug tracker. dill.dump and dill.load works by setting the name using Aclass.__module__ = __name__.

Full code is as follows:

fields = [('float_val', float, field(default=np.nan)),
          ('df', pd.DataFrame, field(default_factory=pd.DataFrame)),
          ('int_val', int, field(default_factory=int)),
          ('time_val', datetime, field(default=datetime.now(timezone.utc)))]

Aclass = make_dataclass('Aclass', fields)
Aclass.__module__ = __name__ # provide name for pickling the class

an_instance=Aclass()

dill.dump(an_instance, open('test.pkl', 'wb'))
dill.load(open('test.pkl', 'rb'))
user_79781120
user_60304240
Related