我想刮取无限滚动实现的页面的所有数据。下面的python代码可以工作。
for i in range(100):
driver.execute_script("window.scrollTo(0, document.body.scrollHeight);")
time.sleep(5)
这意味着每当我向下滚动到底部时，我都需要等待5秒，这通常足以让页面完成加载新生成的内容。但是，这可能并不省时。页面可能在5秒内完成新内容的加载。如何在每次向下滚动时检测页面是否完成了新内容的加载?如果我能检测到这一点，一旦我知道页面完成加载，我就可以再次向下滚动以查看更多内容。这样更节省时间。
当前回答
正如David Cullen的回答中提到的，我总是看到这样的建议:
element_present = EC.presence_of_element_located((By.ID, 'element_id'))
WebDriverWait(driver, timeout).until(element_present)
对于我来说，很难找到所有可以与By一起使用的定位器，所以我认为在这里提供列表会很有用。 根据Ryan Mitchell的Web Scraping with Python:
ID Used in the example; finds elements by their HTML id attribute CLASS_NAME Used to find elements by their HTML class attribute. Why is this function CLASS_NAME not simply CLASS? Using the form object.CLASS would create problems for Selenium's Java library, where .class is a reserved method. In order to keep the Selenium syntax consistent between different languages, CLASS_NAME was used instead. CSS_SELECTOR Finds elements by their class, id, or tag name, using the #idName, .className, tagName convention. LINK_TEXT Finds HTML tags by the text they contain. For example, a link that says "Next" can be selected using (By.LINK_TEXT, "Next"). PARTIAL_LINK_TEXT Similar to LINK_TEXT, but matches on a partial string. NAME Finds HTML tags by their name attribute. This is handy for HTML forms. TAG_NAME Finds HTML tags by their tag name. XPATH Uses an XPath expression ... to select matching elements.
其他回答
把WebDriverWait放在While循环中并捕获异常如何?
from selenium import webdriver
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.common.exceptions import TimeoutException
browser = webdriver.Firefox()
browser.get("url")
delay = 3 # seconds
while True:
try:
WebDriverWait(browser, delay).until(EC.presence_of_element_located(browser.find_element_by_id('IdOfMyElement')))
print "Page is ready!"
break # it will break from the loop once the specific element will be present.
except TimeoutException:
print "Loading took too much time!-Try again"
你试过driver.implicitly_wait吗?它就像驱动程序的一个设置，所以你只在会话中调用它一次，它基本上告诉驱动程序等待给定的时间，直到每个命令都可以执行。
driver = webdriver.Chrome()
driver.implicitly_wait(10)
因此，如果您设置等待时间为10秒，它将尽快执行命令，等待10秒后才放弃。我在类似的滚动场景中使用过这个，所以我不明白为什么它在您的情况下不起作用。希望这对你有帮助。
为了能够修复这个答案，我必须添加新的文本。确保在implicitly_wait中使用小写“w”。
nono = driver.current_url
driver.find_element(By.XPATH,"//button[@value='Send']").click()
while driver.current_url == nono:
pass
print("page loaded.")
正如David Cullen的回答中提到的，我总是看到这样的建议:
element_present = EC.presence_of_element_located((By.ID, 'element_id'))
WebDriverWait(driver, timeout).until(element_present)
对于我来说，很难找到所有可以与By一起使用的定位器，所以我认为在这里提供列表会很有用。 根据Ryan Mitchell的Web Scraping with Python:
ID Used in the example; finds elements by their HTML id attribute CLASS_NAME Used to find elements by their HTML class attribute. Why is this function CLASS_NAME not simply CLASS? Using the form object.CLASS would create problems for Selenium's Java library, where .class is a reserved method. In order to keep the Selenium syntax consistent between different languages, CLASS_NAME was used instead. CSS_SELECTOR Finds elements by their class, id, or tag name, using the #idName, .className, tagName convention. LINK_TEXT Finds HTML tags by the text they contain. For example, a link that says "Next" can be selected using (By.LINK_TEXT, "Next"). PARTIAL_LINK_TEXT Similar to LINK_TEXT, but matches on a partial string. NAME Finds HTML tags by their name attribute. This is handy for HTML forms. TAG_NAME Finds HTML tags by their tag name. XPATH Uses an XPath expression ... to select matching elements.
回答得很好。等待XPATH的快速示例。
# wait for sizes to load - 2s timeout
try:
WebDriverWait(driver, 2).until(expected_conditions.presence_of_element_located(
(By.XPATH, "//div[@id='stockSizes']//a")))
except TimeoutException:
pass
