"Device" can't be pickled

[samurang87]

Hello!

It looks like the "Device" class can't be pickled anymore with your latest major release. We'd like to upgrade to v.2+ but our tests that use multiprocessing fail because of this reason.

Environment details

• OS type and version: local Mac OS 10.15.7, docker python-base:3.8.3-slim-buster
• Python version: 3.8.3
• pip version: 20.1.1
• google-cloud-iot version: 2.0.1

Steps to reproduce

Try to pickle

Code example and resulting stack trace

import pickle
from google.cloud.iot_v1 import Device

device = Device(id="1")
pickled_device = pickle.dumps(device)
print(pickled_device)

Result:

Traceback (most recent call last):
  File "/Users/cmezzavilla/Code/aratrum/.vscode/scratch.py", line 7, in <module>
    pickled_device = pickle.dumps(device)
_pickle.PicklingError: Can't pickle <class 'Device'>: it's not the same object as __main__.Device

Stack trace from test

We have some tests running with multiprocessing, and when trying to upgrade python-iot from 1.0.0 to 2.0.1 they fail like so:

cls = <class 'multiprocessing.reduction.ForkingPickler'>
obj = ('108ed2f80', '__setitem__', ('europe-west1', {'pytest-of-cmezzavilla_aratrum_pytest-1': {'dev_26': id: "dev_26"
name:...pytest-of-cmezzavilla_aratrum_pytest-1/devices/dev_26"
config {
  version: 1
  binary_data: "invalid config"
}
}}), {})
protocol = None

    @classmethod
    def dumps(cls, obj, protocol=None):
        buf = io.BytesIO()
>       cls(buf, protocol).dump(obj)
E       _pickle.PicklingError: Can't pickle <class 'Device'>: attribute lookup Device on __main__ failed

[munkhuushmgl]

@busunkim96 I barely know anything about pickle, Could you answer this question if you have some context?

Otherwise, I will try to find someone else.

[busunkim96]

Hi,

If you need to serialize an object use we recommend using one of the serialization methods provided by proto.Message.

https://proto-plus-python.readthedocs.io/en/latest/messages.html#serialization

from google.cloud.iot_v1 import Device

device = Device(id="1")

# Bytes
serialized_device = Device.serialize(device)
device_from_bytes = Device.deserialize(serialized_device)

# JSON String
json_device = Device.to_json(device)
device_from_json = Device.from_json(json_device)

assert device == device_from_bytes
assert device == device_from_json