Snhps - Quick and easy code snippets

add-cmd-title.py

Rename the CMD window that's running your Python script.

import os

os.system('title {}'.format('My Python Program'))

create-folder-and-file.py

Create a file, ensure that its folder exists, write some content to it, and save it on demand.

import io
import pathlib

#Files are automatically saved at the end of io.open,
#but you can use this function to save them on demand,
#such as during each iteration of a long loop
def save_file(file):
    file.flush()
    os.fsync(file.fileno())

folder_path = 'lorem/ipsum'
file_name = 'foobar.txt'
file_path = folder_path + '/' + file_name

pathlib.Path(folder_path).mkdir(parents=True, exist_ok=True)

with io.open(file_path, 'a', encoding="utf-8-sig", newline='\n') as log_file:
	log_file.write('blah blah blah')
	save_file(log_file)

create-selenium-webdriver.py

A helper function that lets you create a new Selenium webdriver object with just one line of code.

from selenium import webdriver
from selenium.webdriver.chrome.options import Options as ChromeOptions
from selenium.webdriver.firefox.options import Options as FirefoxOptions

def create_webdriver(browser, width, height, is_headless):
    if (browser == 'firefox'):
        firefox_options = FirefoxOptions()
        firefox_options.add_argument('--width={}'.format(width))
        firefox_options.add_argument('--height={}'.format(height))
        if is_headless:
            firefox_options.add_argument('--headless')
        driver = webdriver.Firefox(executable_path = r"..\..\Selenium\geckodriver.exe", options=firefox_options)

    elif (browser == 'chrome'):
        chrome_options = ChromeOptions()
        chrome_options.add_argument('--window-size={},{}'.format(width, height))
        chrome_options.add_experimental_option('excludeSwitches', ['enable-logging']) #Disable JS/browser messages in CMD
        if is_headless:
            chrome_options.add_argument('--headless')
        driver = webdriver.Chrome(executable_path = r"..\..\Selenium\chromedriver.exe", options=chrome_options)

    driver.set_window_size(width, height) #Fallback option; doesn't work in headless mode

    return driver


driver = create_webdriver('chrome', 1200, 900, False)

csv-output.py

Create a comma-delimited CSV file and sanitize its data.

import io
import pathlib
import time

#Sanitize and shrink the given string so that it will fit into a CSV cell
def sanitize_string_for_csv(string):
    if (string == None):
        return '""'
    string = str(string)
    string = string[:32758]
    string = string.replace('"', '""')
    return ('"' + string + '"')


#Convert an array of strings into a valid CSV row string
def generate_csv_row(cells, include_newline):
    if (isinstance(cells, list) == False):
        raise Exception("The first value passed to generate_csv_row must be a list.")
    if (isinstance(include_newline, bool) == False):
        raise Exception("The second value passed to generate_csv_row must be a bool.")
    row_string = ",".join([sanitize_string_for_csv(cell) for cell in cells])
    if (include_newline == True):
        row_string += '\n'
    return row_string


folder_path = 'exports'
file_name = 'foobar-data-' + time.strftime("%b-%d-%Y-%H%M%S").lower() + '.csv'
file_path = folder_path + '/' + file_name

pathlib.Path(folder_path).mkdir(parents=True, exist_ok=True)

with io.open(file_path, 'a', encoding='utf-8-sig', newline='\n') as csv_file:
    csv_file.write(generate_csv_row(['Header 1', 'Header 2'], True))
    csv_file.write(generate_csv_row(['Foo', 'Bar'], True))
    csv_file.write(generate_csv_row(['Lorem', 'Ipsum'], True))

is-selenium-webdriver-alive.py

Check whether the Selenium webdriver object is still alive and connected to its browser process.

from selenium.common.exceptions import NoSuchElementException
from selenium.common.exceptions import WebDriverException

def is_webdriver_alive(driver):
    print('Checking whether the driver is alive')
    try:
        assert(driver.service.process.poll() == None) #Returns an int if dead and None if alive
        driver.service.assert_process_still_running() #Immediately throws a WebDriverException if dead
        driver.find_element_by_tag_name('html') #Throws a NoSuchElementException if dead
        print('The driver appears to be alive')
        return True
    except (NoSuchElementException, WebDriverException, AssertionError):
        print('The driver appears to be dead')
        return False
    except Exception as ex:
        print('Encountered an unexpected exception type ({}) while checking the driver status'.format(type(ex)))
        return False
		

webdriver_status = is_webdriver_alive(driver)

if (webdriver_status == False):
	try:
		driver.quit()
	except:
		pass
	try:
		print('Attempting to create a new webdriver.')
		driver = create_webdriver()
		print('Successfully created a new webdriver.')
	except:
		print('Failed to create a new webdriver.')

main-wrapper.py

Wrap a Python script's main function with an error handler and pause at the end of the script

import os
import time
import traceback

def main():
    do_stuff()
    do_more_stuff()

if (__name__ == "__main__"):
    try:
        os.system('title {}'.format('My Python Program'))
        main()
        input("\nThe script finished successfully. Press the Enter key to exit.")
    except Exception as ex:
        print('The script crashed at ' + time.ctime() + ' due to an unhandled {} exception.'.format(type(ex)))
        print('Full exception text: ' + str(ex))
        print(traceback.format_exc())
        input("\nPress the Enter key to exit.")