Subclassed object results in NoneType

Question

I'm trying to subclass the Chrome WebDriver to include some initialization and cleanup code, but then Python complains that the created object is set to None:

import glob
import selenium
import subprocess
from selenium.webdriver.common.by import By


class WebDriver(selenium.webdriver.Chrome):
    def __init__(self, url, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.url = url

    def __enter__(self):
        self.get(self.url)
        self.implicitly_wait(15)

    def __exit__(self, type, value, traceback):
        self.quit()
        for path in glob.glob('/tmp/.org.chromium.Chromium.*'):
            subprocess.run(['rm', '-rf', path], check=True)


with WebDriver('https://google.com') as driver:
    driver.find_element(By.ID, 'lst-ib').send_keys('Search')

Running the code with Python 3:

$ python3 test.py
Traceback (most recent call last):
  File "test.py", line 43, in <module>
    driver.find_element(By.ID, 'lst-ib').send_keys('Search')
AttributeError: 'NoneType' object has no attribute 'find_element'

score 2 · Accepted Answer · edited May 23 '17 at 11:51

2

Your __enter__() magic method should return self for the driver variable to be pointed to the instance of the WebDriver class:

def __enter__(self):
    self.get(self.url)
    self.implicitly_wait(15)
    return self

To get more information about why and how this works, please see:

edited May 23 '17 at 11:51

Community

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answered Jul 17 '16 at 02:15

alecxe

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Subclassed object results in NoneType

1 Answers1