如何使用 Google Chrome Headless 和 Selenium 提取 youtube 视频的评论数量？

Question

每个 youtube 网页中都有一个元素来显示视频有多少 cmets。 就是这样一个html结构：

<yt-formatted-string class="count-text style-scope ytd-comments-header-renderer">xx Comments</yt-formatted-string>

我想用 selenium 获取号码 xx Comments。
code1-带头浏览器

from selenium import webdriver
from selenium.webdriver.chrome.options import Options
from selenium.common.exceptions import TimeoutException
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.webdriver.common.by import By
import time
options = webdriver.ChromeOptions()
proxy = '127.0.0.1:1080'   
options.add_argument('--proxy-server=socks5://' + proxy)
options.add_argument("start-maximized")
options.add_experimental_option("excludeSwitches", ["enable-automation"])
options.add_experimental_option('useAutomationExtension', False)
driver = webdriver.Chrome(options=options)
wait = WebDriverWait(driver,30)
url='https://www.youtube.com/watch?v=N0lxfilGfak'

driver.get(url)
driver.execute_script("return scrollBy(0, 1000);")
comment = WebDriverWait(driver, 60).until(EC.visibility_of_element_located((By.XPATH, "//yt-formatted-string[contains(., 'Comments')]")))
driver.execute_script("arguments[0].scrollIntoView(true);",comment)
print(driver.find_element_by_xpath("//h2[@id='count']").text)

使用上面的python代码，我可以得到717 Comments for https://www.youtube.com/watch?v=N0lxfilGfak。

现在我想在 selenium 中使用无头浏览器获得相同的数字。
code2-带无头浏览器。

from selenium import webdriver
from selenium.webdriver.chrome.options import Options
from selenium.common.exceptions import TimeoutException
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.webdriver.common.by import By
import time
options = webdriver.ChromeOptions()
proxy = '127.0.0.1:1080'   
options.add_argument('--proxy-server=socks5://' + proxy)
options.add_argument('--no-sandbox')
options.add_argument('--disable-dev-shm-usage')
options.add_argument("--headless")
options.add_argument("start-maximized")
options.add_experimental_option("excludeSwitches", ["enable-automation"])
options.add_experimental_option('useAutomationExtension', False)
driver = webdriver.Chrome(options=options)
wait = WebDriverWait(driver,30)
url='https://www.youtube.com/watch?v=N0lxfilGfak'

driver.get(url)
driver.execute_script("return scrollBy(0, 1000);")
comment = WebDriverWait(driver, 20).until(EC.visibility_of_element_located((By.XPATH, "//yt-formatted-string[contains(., 'Comments')]")))
driver.execute_script("arguments[0].scrollIntoView(true);",comment)
print(driver.find_element_by_xpath("//h2[@id='count']").text)

注意：code2比code1多三行。

options.add_argument('--no-sandbox')
options.add_argument('--disable-dev-shm-usage')
options.add_argument("--headless")

code2和code1中的其他行相同。

执行code2时卡在comment语句中：

>>> comment = WebDriverWait(driver, 60).until(EC.visibility_of_element_located((By.XPATH, "//yt-formatted-string[contains(., 'Comments')]")))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.5/dist-packages/selenium/webdriver/support/wait.py", line 80, in until
    raise TimeoutException(message, screen, stacktrace)
selenium.common.exceptions.TimeoutException: Message: 

为什么在 selenium 中无法使用无头浏览器获取元素？

Answer 1

在我的设置中为headless 设置添加行：

options.add_argument('--window-size=1920,1080')

或者让滚动在 y 方向更长。

driver.execute_script("return scrollBy(0, 5000);")

我的 xpath 表达更直接。

Answer 2

你快到了。要使用Selenium 驱动ChromeDriver 启动google-chrome 浏览上下文 打印文本xx Comments，您必须为visibility_of_element_located() 诱导WebDriverWait，您可以使用以下任一Locator Strategies:

• 使用XPATH和text属性：

  driver.get("https://www.youtube.com/watch?v=N0lxfilGfak")
  driver.execute_script("return scrollBy(0, 1000);")
  subscribe = WebDriverWait(driver, 60).until(EC.visibility_of_element_located((By.XPATH, "//yt-formatted-string[text()='Subscribe']")))
  driver.execute_script("arguments[0].scrollIntoView(true);",subscribe)
  print(WebDriverWait(driver, 10).until(EC.visibility_of_element_located((By.XPATH,"//h2[@id='count']/yt-formatted-string"))).text)
  

• 使用CSS_SELECTOR 和get_attribute()：

  driver.get("https://www.youtube.com/watch?v=N0lxfilGfak")
  driver.execute_script("return scrollBy(0, 1000);")
  subscribe = WebDriverWait(driver, 60).until(EC.visibility_of_element_located((By.XPATH, "//yt-formatted-string[text()='Subscribe']")))
  driver.execute_script("arguments[0].scrollIntoView(true);",subscribe)
  print(WebDriverWait(driver, 10).until(EC.visibility_of_element_located((By.CSS_SELECTOR,"h2#count>yt-formatted-string"))).get_attribute("innerHTML"))
  

• 控制台输出：

  717 Comments
  

• 注意：您必须添加以下导入：

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

---

使用无头 Chrome

使用google-chrome-headless可以使用以下解决方案：

• 代码块：

  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
  
  options = webdriver.ChromeOptions() 
  options.add_experimental_option("excludeSwitches", ["enable-automation"])
  options.add_experimental_option('useAutomationExtension', False)
  options.add_argument('--headless')
  options.add_argument('--window-size=1920,1080')
  driver = webdriver.Chrome(options=options, executable_path=r'C:\WebDrivers\chromedriver.exe')
  driver.get("https://www.youtube.com/watch?v=N0lxfilGfak")
  driver.execute_script("return scrollBy(0, 1000);")
  subscribe = WebDriverWait(driver, 60).until(EC.visibility_of_element_located((By.XPATH, "//yt-formatted-string[text()='Subscribe']")))
  driver.execute_script("arguments[0].scrollIntoView(true);",subscribe)
  # using xpath and text attribute
  print(WebDriverWait(driver, 10).until(EC.visibility_of_element_located((By.XPATH,"//h2[@id='count']/yt-formatted-string"))).text)
  # using cssSelector and get_attribute()
  print(WebDriverWait(driver, 10).until(EC.visibility_of_element_located((By.CSS_SELECTOR,"h2#count>yt-formatted-string"))).get_attribute("innerHTML"))
  print("Exiting")
  driver.quit()
  

• 控制台输出：

  717 Comments
  717 Comments
  Exiting