在Python中使用Selenium显式等待

如何解决在Python中使用Selenium显式等待

我有一个IP列表，这些IP用于当前已部署的约600个调制解调器。这些调制解调器中的某些将可访问，而某些则可能不是由于连接性或电池已耗尽。基本上想遍历所有IP，并明确等待包含调制解调器固件版本的底部文本字符串。如果工作站未加载，我希望它添加“无连接”来代替IP。我想将该固件附加到一个空列表中，然后将该列表打印到csv中。

我的主要障碍似乎是WebDriverWait（driver，30）。直到我以前从同一定位器提取代码时，直到代码的一部分似乎总是引发异常。我看到浏览器负载，然后它仍然会引发异常。我已经尝试了几种“标准预期条件”，但似乎都没有用。

from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.common.by import By
from selenium.webdriver.chrome.options import Options
from selenium.webdriver.support.ui import Select
import os
import csv

prefix = 'http://'
suffix = ':9191'

fwlist = []
iplist = ["###.###.###.###",...]


class presence_of_element_located(object):
    """ An expectation for checking that an element is present on the DOM
    of a page. This does not necessarily mean that the element is visible.
    locator - used to find the element
    returns the WebElement once it is located
    """
    def __init__(self,locator):
        self.locator = locator

    def __call__(self,driver):
        return _find_element(driver,self.locator)

for ip in iplist:
        url = prefix + ip + suffix
        # instantiate a chrome options object so you can set the size and headless preference
        # some of these chrome options might be uncessary but I just used a boilerplate
        # change the <path_to_download_default_directory> to whatever your default download folder is located
        chrome_options = Options()
        #chrome_options.add_argument("--headless")
        chrome_options.add_argument("--window-size=1920x1080")
        chrome_options.add_argument("--disable-notifications")
        chrome_options.add_argument('--no-sandbox')
        chrome_options.add_argument('--verbose')
        chrome_options.add_experimental_option("prefs",{
                "download.default_directory": r"Z:\Python\Scaping\Chromedriver\chromedriver.exe","download.prompt_for_download": False,"download.directory_upgrade": True,"safebrowsing_for_trusted_sources_enabled": False,"safebrowsing.enabled": False
        })
        #chrome_options.add_argument('--disable-software-rasterizer')
        # initialize driver object and change the <path_to_chrome_driver> depending on your directory where your chromedriver should be
        driver = webdriver.Chrome(chrome_options=chrome_options,executable_path=r"Z:\Python\Scaping\Chromedriver\chromedriver.exe")
        # get request to target the site selenium is active on
        driver.get(f'{url}')
        try:
                WebDriverWait(driver,30,.5).until(presence_of_element_located((By.ID,"login_screen")))
                print(f'{url} is ready')
        except:
                print(f'Timeout for {url}')
                fw = 'No connection'
                fwlist.append(fw)

        text = driver.find_element_by_xpath("/html/body/div[2]/div/div[2]/div[4]").text
        fw = text.split(' ',3)
        fwlist.append(fw[3])
        print(fwlist)
        driver.close()

with open('Scaping\PGE-FW.csv','w',newline='') as f:
    writer = csv.writer(f)
    writer.writerows(fw)

driver.quit()

为了进行测试，我使用了一个工作IP和一个不工作IP，但是在30秒内我看到一个工作IP可以正常工作，但这总是一个例外。

下面是html的图像，其中包含等待的ID和所需数据的xpath。我真的不知道为大家提供调制解调器内部网页html的方法，但是如果有人可以，请告诉我。因此，我想我有两个问题：我是否犯了一个明显的错误，为什么这不起作用，或者也许有更好的方法来解决这个问题？

解决方法

忘记了导入。

Needed:
from selenium.webdriver.support import expected_conditions as EC

From:
WebDriverWait(driver,30,.5).until(presence_of_element_located((By.ID,"login_screen")))

To:
WebDriverWait(driver,.5).until(EC.presence_of_element_located((By.ID,"login_screen")))