Start from the beginning using while loop on connection times out using Selenium and Python

问题

from selenium import webdriver
import time

browser = webdriver.Chrome('C:/Users/acer/Desktop/chromedriver')
browser.get('website')

def user():
    while True:
        time.sleep(1)
        try:
            browser.find_element_by_id('q').send_keys('name') #Type in name
            browser.find_element_by_tag_name('button').click()  #Click "verify"

        finally:
            browser.find_element_by_tag_name('button').click()  #When connection times out, click "try again"
user()      #When connection times out again run "while loop" from the begining

I want to start from the beginning when the connection times out again and make a never ending loop until connection is successful.

回答1:

Seems you were near perfect. To demonstrate "to start from the beginning when the connection times out again and make a never ending loop until connection is successful" here is a small program which does the following:

• Opens the url https://www.google.com/
• Finds out the element By.NAME, "q"
• Clears the field
• Sends the character sequence name
• Attempts to click on the element find_element_by_tag_name('button')
• Fails and using continue keeps on retrying.

• Code Block:

  from selenium import webdriver
  from selenium.webdriver.support.ui import WebDriverWait
  from selenium.webdriver.common.by import By
  from selenium.webdriver.support import expected_conditions as EC
  from selenium.common.exceptions import TimeoutException, WebDriverException
  
  options = webdriver.ChromeOptions() 
  options.add_argument("start-maximized")
  options.add_experimental_option("excludeSwitches", ["enable-automation"])
  options.add_experimental_option('useAutomationExtension', False)
  browser = webdriver.Chrome(options=options, executable_path=r'C:\WebDrivers\chromedriver.exe')
  browser.get('https://www.google.com/')
  def user():
      while True:
          print("Starting while loop")
          try:
              element = WebDriverWait(browser, 20).until(EC.element_to_be_clickable((By.NAME, "q")))
              element.clear() #clear the previous text
              element.send_keys('name') #Type in name
              browser.find_element_by_tag_name('button').click()
          except (WebDriverException, TimeoutException):
              print("Go to while loop from the begining")
              continue
  user()
  

• Console Output:

  Starting while loop
  Go to while loop from the begining
  Starting while loop
  Go to while loop from the begining
  Starting while loop
  Go to while loop from the begining
  .
  .
  .
  

---

This usecase

You can follow similar logic and your effective code block will be:

from selenium import webdriver
import time

browser = webdriver.Chrome('C:/Users/acer/Desktop/chromedriver')
browser.get('website')

def user():
    while True:
    time.sleep(1)
    try:
        browser.find_element_by_id('q').send_keys('name') #Type in name
        browser.find_element_by_tag_name('button').click()  #Click "verify"

    except WebDriverException:
        continue #When connection times out again run "while loop" from the begining
user()

回答2:

So you're almost there. You need to use try/except rather than try/finally.

Selenium will raise a timeout exception. except and finally are both used to when dealing with exceptions:

• except when python raises an exception the program will exit unless you catch the exception using an except branch
• finally if an exception is raised, any code in the finally branch is executed before the program exits.

If you use an except branch then the program will just loop around again. Make sure that you catch the specific timeout exception in the except branch otherwise your program will slow all errors!

来源：https://stackoverflow.com/questions/59811236/start-from-the-beginning-using-while-loop-on-connection-times-out-using-selenium