No module named pathlib2

Question

I've been working on getting Google Assistant working on my Raspberry Pi 3. It is working but I'm having problems getting this specific step to work: https://developers.google.com/assistant/sdk/guides/library/python/extend/handle-device-commands

This step covers sending an on/off command to the Pi to turn a LED bulb on or off. I have confirmed the Bread board and LED is setup correctly because I can turn the LED on or off via a python script.

However, after following the steps in that page and trying to run the following command "python hotword.py --device_model_id my-model" (which is actually: python hotword.py --device_model_id assistantraspi-1d671-pigooglev2-8n98u3) I get the following error: ImportError: No module named pathlib2

I am including a copy of that file (hotword.py)

#!/usr/bin/env python

# Copyright (C) 2017 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


from __future__ import print_function

import argparse
import json
import os.path
import pathlib2 as pathlib
import RPi.GPIO as GPIO

import google.oauth2.credentials

from google.assistant.library import Assistant
from google.assistant.library.event import EventType
from google.assistant.library.file_helpers import existing_file
from google.assistant.library.device_helpers import register_device

try:
    FileNotFoundError
except NameError:
    FileNotFoundError = IOError


WARNING_NOT_REGISTERED = """
    This device is not registered. This means you will not be able to use
    Device Actions or see your device in Assistant Settings. In order to
    register this device follow instructions at:

    https://developers.google.com/assistant/sdk/guides/library/python/embed/register-device
"""


def process_event(event):
    """Pretty prints events.

    Prints all events that occur with two spaces between each new
    conversation and a single space between turns of a conversation.

    Args:
        event(event.Event): The current event to process.
    """
    if event.type == EventType.ON_CONVERSATION_TURN_STARTED:
        print()

    print(event)

    if (event.type == EventType.ON_CONVERSATION_TURN_FINISHED and
            event.args and not event.args['with_follow_on_turn']):
        print()
    if event.type == EventType.ON_DEVICE_ACTION:
        for command, params in event.actions:
            print('Do command', command, 'with params', str(params))
            if command == "action.devices.commands.OnOff":
                if params['on']:
                    print('Turning the LED on.')
                    GPIO.output(25, 1)
                else:
                    print('Turning the LED off.')
                    GPIO.output(25, 0)

def main():
    parser = argparse.ArgumentParser(
        formatter_class=argparse.RawTextHelpFormatter)
    parser.add_argument('--device-model-id', '--device_model_id', type=str,
                        metavar='DEVICE_MODEL_ID', required=False,
                        help='the device model ID registered with Google')
    parser.add_argument('--project-id', '--project_id', type=str,
                        metavar='PROJECT_ID', required=False,
                        help='the project ID used to register this device')
    parser.add_argument('--device-config', type=str,
                        metavar='DEVICE_CONFIG_FILE',
                        default=os.path.join(
                            os.path.expanduser('~/.config'),
                            'googlesamples-assistant',
                            'device_config_library.json'
                        ),
                        help='path to store and read device configuration')
    parser.add_argument('--credentials', type=existing_file,
                        metavar='OAUTH2_CREDENTIALS_FILE',
                        default=os.path.join(
                            os.path.expanduser('~/.config'),
                            'google-oauthlib-tool',
                            'credentials.json'
                        ),
                        help='path to store and read OAuth2 credentials')
    parser.add_argument('-v', '--version', action='version',
                        version='%(prog)s ' + Assistant.__version_str__())

    args = parser.parse_args()
    with open(args.credentials, 'r') as f:
        credentials = google.oauth2.credentials.Credentials(token=None,
                                                            **json.load(f))

    device_model_id = None
    last_device_id = None
    try:
        with open(args.device_config) as f:
            device_config = json.load(f)
            device_model_id = device_config['model_id']
            last_device_id = device_config.get('last_device_id', None)
    except FileNotFoundError:
        pass

    if not args.device_model_id and not device_model_id:
        raise Exception('Missing --device-model-id option')

    # Re-register if "device_model_id" is given by the user and it differs
    # from what we previously registered with.
    should_register = (
        args.device_model_id and args.device_model_id != device_model_id)

    device_model_id = args.device_model_id or device_model_id

    with Assistant(credentials, device_model_id) as assistant:
        events = assistant.start()

        device_id = assistant.device_id
        print('device_model_id:', device_model_id)
        print('device_id:', device_id + '\n')
        GPIO.setmode(GPIO.BCM)
        GPIO.setup(25, GPIO.OUT, initial=GPIO.LOW)

        # Re-register if "device_id" is different from the last "device_id":
        if should_register or (device_id != last_device_id):
            if args.project_id:
                register_device(args.project_id, credentials,
                                device_model_id, device_id)
                pathlib.Path(os.path.dirname(args.device_config)).mkdir(
                    exist_ok=True)
                with open(args.device_config, 'w') as f:
                    json.dump({
                        'last_device_id': device_id,
                        'model_id': device_model_id,
                    }, f)
            else:
                print(WARNING_NOT_REGISTERED)

        for event in events:
            process_event(event)


if __name__ == '__main__':
    main()

Answer 1

Have you tried installing pathlib2 with pip or pip3? Please try

pip install pathlib2

if you're using Python2, and

pip3 install pathlib2

if you're using Python3. However, If pip is not found, then try installing it with

apt-get install python-pip python3-pip

Answer 2

Thanks for the suggestions. Turns out the solution was pretty simple.

The solution is two fold: 1: I have to run the following command first:

source env/bin/activate

Then I could run the python script without getting an error

(env) pi@raspberrypi:~/assistant-sdk-python/google-assistant-sdk/googlesamples/assistant/library $ python hotword.py --device_model_id assistantraspi-1d671-pigooglev2-8n98u3

As I progressed through the articles, the source becomes deactivated per se and returns to a normal prompt with first starting with (env).
Trying to run the python script without first loading the source command was the problem.

I still haven't wrapped my head around how this all works but I'll keep plugging along and hopefully understand what running this command first does

source env/bin/activate