【发布时间】：2022-01-28 01:49:34
【问题描述】：
我一直在关注这个教程：https://kb.objectrocket.com/postgresql/scrape-a-website-to-postgres-with-python-938
我的 app.py 文件如下所示（取自上述教程）：
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/local/bin/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()
我已成功导入所需的库，并创建了一个数据库来存储抓取的数据。但是，当我运行应用程序时，我收到以下错误：
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)
[2021-12-29 18:14:58,672] ERROR in app: Exception on / [GET]
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 33, in import_temp
my_web_driver.get("<a href='" + t_url + "'>" + t_url + "</a>")
File "/home/lloyd/PycharmProjects/flaskProject/venv/lib/python3.6/site-packages/selenium/webdriver/remote/webdriver.py", line 333, in get
self.execute(Command.GET, {'url': url})
File "/home/lloyd/PycharmProjects/flaskProject/venv/lib/python3.6/site-packages/selenium/webdriver/remote/webdriver.py", line 321, in execute
self.error_handler.check_response(response)
File "/home/lloyd/PycharmProjects/flaskProject/venv/lib/python3.6/site-packages/selenium/webdriver/remote/errorhandler.py", line 242, in check_response
raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.InvalidArgumentException: Message: invalid argument
(Session info: chrome=96.0.4664.110)
127.0.0.1 - - [29/Dec/2021 18:14:58] "GET / HTTP/1.1" 500 -
我认为网络驱动程序无法处理 url：
my_web_driver.get("<a href='" + t_url + "'>" + t_url + "</a>")
如果有人能让我了解为什么会发生这种情况，将不胜感激。
【问题讨论】：
-
为什么要传递一个html字符串（
a标签）？只需传递网址。 -
啊，我明白了——是教程错了。这里是the docs。只要找到像样的教程。