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No Internet connection when running a Python script - Printable Version

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No Internet connection when running a Python script - basil_555 - Mar-10-2024

Hello. I have the follwoing Python code that checks a website for change. This script always gives me an error "Error checking website". What am I doing wrong?

import requests
import os
from bs4 import BeautifulSoup
import time
import logging
import smtplib as smtp

URL_TO_MONITOR = "https://www.yahoo.com/" #change this to the URL you want to monitor
DELAY_TIME = 15 # seconds

def process_html(string):
soup = BeautifulSoup(string, features="lxml")

    # make the html look good
    soup.prettify()
    
    # remove script tags
    for s in soup.select('script'):
        s.extract()
    
    # remove meta tags 
    for s in soup.select('meta'):
        s.extract()
    
    # convert to a string, remove '\r', and return
    return str(soup).replace('\r', '')

def webpage_was_changed():
"""Returns true if the webpage was changed, otherwise false."""
headers = {'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.95 Safari/537.36',
'Pragma': 'no-cache', 'Cache-Control': 'no-cache'}
response = requests.get(URL_TO_MONITOR, headers=headers)

    # create the previous_content.txt if it doesn't exist
    if not os.path.exists("previous_content.txt"):
        open("previous_content.txt", 'w+').close()
    
    filehandle = open("previous_content.txt", 'r')
    previous_response_html = filehandle.read() 
    filehandle.close()
    
    processed_response_html = process_html(response.text)
    
    if processed_response_html == previous_response_html:
        return False
    else:
        filehandle = open("previous_content.txt", 'w')
        filehandle.write(processed_response_html)
        filehandle.close()
        return True

def main():
log = logging.getLogger(__name__)
logging.basicConfig(level=os.environ.get("LOGLEVEL", "INFO"), format='%(asctime)s %(message)s')
log.info("Running Website Monitor")
while True:
try:
if webpage_was_changed():
log.info("WEBPAGE WAS CHANGED.")

                print("The website was changed")
            else:
                log.info("Webpage was not changed.")
        except:
            log.info("Error checking website.")
        time.sleep(DELAY_TIME)

if __name__ == "__main__":
main()


RE: No Internet connection when running a Python script - buran - Mar-10-2024

The indentation is a mess. Fix that in your post. Also don't use bare except. Remove the try/except to get meaningful error message na debug properly

RE: No Internet connection when running a Python script - deanhystad - Mar-10-2024

I suggest not using try/except at all. That will provide more information about the problem.

RE: No Internet connection when running a Python script - DeaD_EyE - Mar-10-2024 

import requests
import os
from bs4 import BeautifulSoup
import time
import logging
import smtplib as smtp

try:
    import lxml
except ImportError:
    raise RuntimeError("Please install lxml")


URL_TO_MONITOR = "https://www.yahoo.com/"  # change this to the URL you want to monitor
DELAY_TIME = 15  # seconds


def process_html(string):
    soup = BeautifulSoup(string, features="lxml")

    # make the html look good
    soup.prettify()

    # remove script tags
    for s in soup.select("script"):
        s.extract()

    # remove meta tags
    for s in soup.select("meta"):
        s.extract()

    # convert to a string, remove '\r', and return
    return str(soup).replace("\r", "")


def webpage_was_changed():
    """Returns true if the webpage was changed, otherwise false."""
    headers = {
        "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.95 Safari/537.36",
        "Pragma": "no-cache",
        "Cache-Control": "no-cache",
    }
    response = requests.get(URL_TO_MONITOR, headers=headers)

    # create the previous_content.txt if it doesn't exist
    if not os.path.exists("previous_content.txt"):
        open("previous_content.txt", "w+").close()

    filehandle = open("previous_content.txt", "r")
    previous_response_html = filehandle.read()
    filehandle.close()

    processed_response_html = process_html(response.text)

    if processed_response_html == previous_response_html:
        return False
    else:
        filehandle = open("previous_content.txt", "w")
        filehandle.write(processed_response_html)
        filehandle.close()
        return True


def main():
    log = logging.getLogger(__name__)
    logging.basicConfig(
        level=os.environ.get("LOGLEVEL", "INFO"), format="%(asctime)s %(message)s"
    )
    log.info("Running Website Monitor")

    while True:
        try:
            if webpage_was_changed():
                log.info("WEBPAGE WAS CHANGED.")
            else:
                log.info("Webpage was not changed.")

        except Exception as e:
            log.exception(e)

        time.sleep(DELAY_TIME)


if __name__ == "__main__":
    main()
Do not use a bare except. It suppresses programming errors. In this case lxml wasn't installed, which is required by bs4 (explicit features="lxml").

I didn't check the other stuff, just used an format tool (ruff format).

RE: No Internet connection when running a Python script - buran - Mar-10-2024

(Mar-10-2024, 05:53 PM)DeaD_EyE Wrote: In this case lxml wasn't installed,
well, I don't know how you know it is not installed on OP machine

RE: No Internet connection when running a Python script - DeaD_EyE - Mar-10-2024

(Mar-10-2024, 07:28 PM)buran Wrote: well, I don't know how you know it is not installed on OP machine

I tested his code and ran into this issue. lxml was not installed.

RE: No Internet connection when running a Python script - buran - Mar-10-2024

(Mar-10-2024, 08:49 PM)DeaD_EyE Wrote: I tested his code and ran into this issue. lxml was not installed.
It was not installed on YOUR machine. There is no info about OP setup - may or may not be installed, we just don't know

RE: No Internet connection when running a Python script - DeaD_EyE - Mar-10-2024

(Mar-10-2024, 10:11 PM)buran Wrote: It was not installed on YOUR machine. There is no info about OP setup - may or may not be installed, we just don't know

This is why I mentioned, that bare excepts are bad. Further, I had this issue with lxml, which is also eaten up by the bare except. The exception was raised by bs4. If his internet connection does not work, then he will see it with the modified code:

        except Exception as e:
            log.exception(e)


RE: No Internet connection when running a Python script - snippsat - Mar-11-2024

Some improvement,like time.sleep(blocking) is not the best for schedule stuff.
So schedule and loguru(great) for logging. 
import requests
import os
from bs4 import BeautifulSoup
import time
from loguru import logger
logger.add("log_file.log", rotation="2 days")
import schedule
try:
    from lxml import etree
except ImportError:
    raise RuntimeError("Please install lxml with `pip install lxml`")

URL_TO_MONITOR = "https://hckrnews.com/"
CHECK_INTERVAL = 15

def process_html(site_content):
    soup = BeautifulSoup(site_content, features="lxml")
    # Combining tag selections
    for s in soup(["script", "meta"]):
        s.extract()
    return str(soup).replace("\r", "")

def webpage_was_changed():
    headers = {
        "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.95 Safari/537.36",
        "Pragma": "no-cache",
        "Cache-Control": "no-cache",
    }
    response = requests.get(URL_TO_MONITOR, headers=headers)
    if not os.path.exists("previous_content.txt"):
        open("previous_content.html", "w+").close()
    with open("previous_content.html", "r+") as filehandle:
        previous_response_html = filehandle.read()
        processed_response_html = process_html(response.content)
        if processed_response_html != previous_response_html:
            filehandle.seek(0)
            filehandle.write(processed_response_html)
            filehandle.truncate()
            return True
    return False

def check_webpage():
    try:
        if webpage_was_changed():
            logger.info("WEBPAGE WAS CHANGED.")
        else:
            logger.info("Webpage was not changed.")
    except Exception as e:
        logger.exception(e)

def main():
    schedule.every(CHECK_INTERVAL).seconds.do(check_webpage)
    logger.info("Running Website Monitor")
    while True:
        schedule.run_pending()
        time.sleep(1)

if __name__ == "__main__":
    main()
Also a tips i would say that soup.prettify() is broken,make new lines in tag so dos look like standard HTML at all.
Use Prettier have a command line tool so do just prettier --write . in folder then get correct formatted HTML.