Why am I receiving 'Internal Server Error' - when attempting to use Python Flask?

Question

I have been following this tutorial: https://kb.objectrocket.com/postgresql/scrape-a-website-to-postgres-with-python-938

My app.py file looks like this (taken from the above tutorial):

from flask import Flask  # needed for flask-dependent libraries below
from flask import render_template  # to render the error page
from selenium import webdriver  # to grab source from URL
from bs4 import BeautifulSoup  # for searching through HTML
import psycopg2  # for database access

# set up Postgres database connection and cursor.
t_host = "localhost" # either "localhost", a domain name, or an IP address.
t_port = "5432" # default postgres port
t_dbname = "scrape"
t_user = "postgres"
t_pw = "********?"
db_conn = psycopg2.connect(host=t_host, port=t_port, dbname=t_dbname, user=t_user, password=t_pw)
db_cursor = db_conn.cursor()

app = Flask(__name__)


@app.route("/")
@app.route('/import_temp')
def import_temp():
    # set up your webdriver to use Chrome web browser
    my_web_driver = webdriver.Chrome("/usr/lib/chromium-browser/chromedriver")

    # designate the URL we want to scrape
    #   NOTE: the long string of characters at the end of this URL below is a clue that
    #   maybe this page is so dynamic, like maybe refers to a specific web session and/or day/time,
    #   that we can't necessarily count on it to be the same more than one time.
    #   Which means... we may want to find another source for our data; one that is more
    #   dependable. That said, whatever URL you use, the methodology in this lesson stands.
    t_url = "https://weather.com/weather/today/l/7ebb344012f0c5ff88820d763da89ed94306a86c770fda50c983bf01a0f55c0d"
    # initiate scrape of website page data
    my_web_driver.get("<a href='" + t_url + "'>" + t_url + "</a>")
    # return entire page into "t_content"
    t_content = my_web_driver.page_source
    # use soup to make page content easily searchable
    soup_in_bowl = BeautifulSoup(t_content)
    # search for the UNIQUE span and class for the data we are looking for:
    o_temp = soup_in_bowl.find('span', attrs={'class': 'deg-feels'})
    # from the resulting object, "o_temp", get the text parameter and assign it to "n_temp"
    n_temp = o_temp.text

    # Build SQL for purpose of:
    #    saving the temperature data to a new row
    s = ""
    s += "INSERT INTO tbl_temperatures"
    s += "("
    s += "n_temp"
    s += ") VALUES ("
    s += "(%n_temp)"
    s += ")"

    # Trap errors for opening the file
    try:
        db_cursor.execute(s, [n_temp, n_temp])
        db_conn.commit()
    except psycopg2.Error as e:
        t_msg = "Database error: " + e + "/n open() SQL: " + s
        return render_template("error_page.html", t_msg = t_msg)

    # Success!
    # Show a message to user.
    t_msg = "Successful scrape!"
    return render_template("progress.html", t_msg = t_msg)

    # Clean up the cursor and connection objects
    db_cursor.close()
    db_conn.close()

Python Shell Error Log:

FLASK_APP = app.py
FLASK_ENV = development
FLASK_DEBUG = 0
In folder /home/lloyd/PycharmProjects/flaskProject
/home/lloyd/PycharmProjects/flaskProject/venv/bin/python -m flask run
 * Serving Flask app 'app.py' (lazy loading)
 * Environment: development
 * Debug mode: off
 * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
[2021-12-28 09:57:24,823] ERROR in app: Exception on / [GET]
Traceback (most recent call last):
  File "/home/lloyd/PycharmProjects/flaskProject/venv/lib/python3.6/site-packages/selenium/webdriver/common/service.py", line 76, in start
    stdin=PIPE)
  File "/usr/lib64/python3.6/subprocess.py", line 729, in __init__
    restore_signals, start_new_session)
  File "/usr/lib64/python3.6/subprocess.py", line 1364, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: '/usr/lib/chromium-browser/chromedriver': '/usr/lib/chromium-browser/chromedriver'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/lloyd/PycharmProjects/flaskProject/venv/lib/python3.6/site-packages/flask/app.py", line 2073, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/lloyd/PycharmProjects/flaskProject/venv/lib/python3.6/site-packages/flask/app.py", line 1518, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/lloyd/PycharmProjects/flaskProject/venv/lib/python3.6/site-packages/flask/app.py", line 1516, in full_dispatch_request
    rv = self.dispatch_request()
  File "/home/lloyd/PycharmProjects/flaskProject/venv/lib/python3.6/site-packages/flask/app.py", line 1502, in dispatch_request
    return self.ensure_sync(self.view_functions[rule.endpoint])(**req.view_args)
  File "/home/lloyd/PycharmProjects/flaskProject/app.py", line 23, in import_temp
    my_web_driver = webdriver.Chrome("/usr/lib/chromium-browser/chromedriver")
  File "/home/lloyd/PycharmProjects/flaskProject/venv/lib/python3.6/site-packages/selenium/webdriver/chrome/webdriver.py", line 73, in __init__
    self.service.start()
  File "/home/lloyd/PycharmProjects/flaskProject/venv/lib/python3.6/site-packages/selenium/webdriver/common/service.py", line 83, in start
    os.path.basename(self.path), self.start_error_message)
selenium.common.exceptions.WebDriverException: Message: 'chromedriver' executable needs to be in PATH. Please see https://sites.google.com/a/chromium.org/chromedriver/home

127.0.0.1 - - [28/Dec/2021 09:57:24] "GET / HTTP/1.1" 500 -
127.0.0.1 - - [28/Dec/2021 09:57:25] "GET /favicon.ico HTTP/1.1" 404 -

Web Console Error:

Internal Server Error
The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.

I did previously post a similar question re a 404 ERROR here: Why am I receiving ERROR 404 - when attempting to use Python Flask

Any help would be greatly appreciated. Cheers

Answer 1

when you requesting a '/' there is an exception in the code. because there is a problem with your set up with selenium.

have you thought about using requests ( https://docs.python-requests.org/en/latest/ ). what requests will give you is content of the webpage, with out needing to define a webdriver.

from requests import get

req = get() # put in your own url
content = req.text() # gets the content of the site, which will be HTML
bs = BeautifulSoup(content, 'html.parser')