Selenium - 找不到网站中 100% 存在的元素

Question

I am doing a side project for fun to automate the website https://10fastfingers.com/ in order for Selenium to complete all achievements of the website automatically. You can find my current code in my repository: https://github.com/jasperan/pyfastfingers

However, I have encountered a problem with the login page:

https://10fastfingers.com/login

Selenium does not let me locate the following HTML tags, whose corresponding xpath values are presented below, right away:

//*[@id="UserEmail"]

[//*[@id="UserPassword"]

It seems like the website does not load them properly the first time, because even when I inspect these manually (with my own web client, Firefox, Chrome, or even Chromium but launched by myself...), I get automatically redirected to its grandparent:

/html/body

When I've located this element manually, after a second inspection I can redirect to my desired email and password elements.

However, programatically, I can't do that. No matter how many times I try to locate the element, it doesn't properly locate, throwing me the following exception every time:

 File "pyfastfingers.py", line 112, in <module>
   main()
 File "pyfastfingers.py", line 100, in main
   do_login(driver)
 File "pyfastfingers.py", line 74, in do_login
   password = driver.find_element_by_xpath('[//*[@id="UserPassword"]')
 File "/home/j/.local/lib/python3.6/site-packages/selenium/webdriver/remote/webdriver.py", line 394, in find_element_by_xpath
   return self.find_element(by=By.XPATH, value=xpath)
 File "/home/j/.local/lib/python3.6/site-packages/selenium/webdriver/remote/webdriver.py", line 978, in find_element
   'value': value})['value']
 File "/home/j/.local/lib/python3.6/site-packages/selenium/webdriver/remote/webdriver.py", line 321, in execute
   self.error_handler.check_response(response)
 File "/home/j/.local/lib/python3.6/site-packages/selenium/webdriver/remote/errorhandler.py", line 242, in check_response
   raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.InvalidSelectorException: Message: invalid selector: Unable to locate an element with the xpath expression [//*[@id="UserPassword"] because of the following error:
SyntaxError: Failed to execute 'evaluate' on 'Document': The string '[//*[@id="UserPassword"]' is not a valid XPath expression.
 (Session info: chrome=74.0.3729.169)
 (Driver info: chromedriver=74.0.3729.6 (255758eccf3d244491b8a1317aa76e1ce10d57e9-refs/branch-heads/3729@{#29}),platform=Linux 4.18.0-21-generic x86_64)

Here is some code that corresponds to my login function:

    driver.get('https://10fastfingers.com/login')

    placeholder = driver.find_element_by_xpath('/html/body')
    email = driver.find_element_by_xpath('//*[@id="UserEmail"]')
    password = driver.find_element_by_xpath('[//*[@id="UserPassword"]')
    email.send_keys(os.environ['FINGERS_EMAIL'])
    password.send_keys(os.environ['FINGERS_PASSWORD'])
    login_button = driver.find_element_by_id('login-form-submit')
    login_button.click()
    # Login complete

You can find the complete code in my repository.

Answer 1

The issue is in

driver.find_element_by_xpath('[//*[@id="UserPassword"]')

Remove first '[' in the xpath.

driver.find_element_by_xpath('//*[@id="UserPassword"]')

Answer 2

Have you tried the wait until function.

wait = WebDriverWait(driver, 10)
men_menu = wait.until(ec.visibility_of_element_located((By.XPATH, "//*[@id="UserPassword"]")))

Answer 3

Your issue is xpath expression:

[//*[@id="UserPassword"]

It should be:

//*[@id="UserPassword"]

But it seem like you can use .find_element_by_id instead .find_element_by_xpath , looks better.

driver.get('https://10fastfingers.com/login')

email = WebDriverWait(driver, 20).until(EC.visibility_of_element_located((By.ID, 'UserEmail')))
email.send_keys(os.environ['FINGERS_EMAIL'])

password = driver.find_element_by_id('UserPassword')
login_button = driver.find_element_by_id('login-form-submit')

password.send_keys(os.environ['FINGERS_PASSWORD'])
login_button.click()

Following import:

from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC