如何让 Selenium WebDriver 等到 <dd> 元素包含数据后再继续？

Question

我正在尝试自动为 Pingdom 的网站速度测试提供一个 url（请参阅 http://tools.pingdom.com/fpt/），然后提取并打印该测试的结果。

我已经编写了一些代码，但我不知道如何从“Perf.等级'元素。

似乎该元素在测试运行之前就存在（我猜它是在服务器端运行的？）但是是空的。然后，一旦测试完成，该元素就会填充该值。

如何让 Selenium 等到填充此值后再尝试打印？

这是我的代码：

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

# Pingdom Website Speed Test
for i in range(0, 1):

    # Initialises chromedriver
    driver = webdriver.Chrome(executable_path=r'C:\Users\Desktop\Python\chromedriver\chromedriver.exe')

    # Opens Pingdom homepage
    driver.get('http://tools.pingdom.com/fpt/')

    # Looks for search box, enters 'http://www.url.com/' and submits it
    pingdom_url_element = driver.find_element_by_id('urlinput')
    pingdom_url_element.send_keys('http://www.url.com/')
    pingdom_test_button_element = "//button[@tabindex='2']"
    driver.find_element_by_xpath(pingdom_test_button_element).click()

    # Waits until page has loaded then looks for attribute containing the report score's value and returns the value
    pingdom_performance_result = WebDriverWait(driver, 60).until(EC.presence_of_element_located((By.XPATH, "//div[@id='rt_sumright']/dl[@class='last']/dd[1]")))

    print('Pingdom score:')
    print(datetime.datetime.now().strftime("%d-%m-%Y %H:%M:%S"), "---", pingdom_performance_result.text)

    driver.close()

    i += 1

Answer 1

您可以创建 custom expected condition 并等待成绩有值 - 或者，在这种情况下匹配特定的正则表达式：

from selenium.common.exceptions import StaleElementReferenceException
from selenium.webdriver.support import expected_conditions as EC

class wait_for_text_to_match(object):
    def __init__(self, locator, pattern):
        self.locator = locator
        self.pattern = pattern

    def __call__(self, driver):
        try:
            element_text = EC._find_element(driver, self.locator).text
            return self.pattern.search(element_text)
        except StaleElementReferenceException:
            return False

用法：

import re

wait = WebDriverWait(driver, 60)
pattern = re.compile(r"\d+/\d+")
pingdom_performance_result = wait.until(wait_for_text_to_match((By.XPATH, "//div[@id='rt_sumright']/dl[@class='last']/dd[1]"), pattern))

print(pingdom_performance_result.text)