为什么我的 Selenium xpath 表达式返回 [object attribute] 而不是元素？

Question

我正在制作一个刮板，它将通过我的网页并抓取所有链接。许多链接都在封闭列表中，也称为树。因此，我找到了包含所有链接的 xpath。我在 google inspect 中运行了以下 xpath，它运行得非常好，给了我以下输出。

var result=$x("//div[@id='index__tree']//a[contains(text(),doku.php)]/@href")

result[0].value
"/doku.php?ihome"
result[4].value
"/doku.php?start"

我将 xpath 转换为 selenium 代码：​​

a = driver.find_elements_by_xpath("//div[@id='index__tree']//a[contains(text(),doku.php)]/@href")

for aa in a:
        print(aa)

然后我运行代码并收到以下错误：

opening browser
Login Successful
Traceback (most recent call last):
  File "wiki.py", line 49, in <module>
    a = driver.find_elements_by_xpath("//div[@id='index__tree']//a[contains(text(),doku.php)]/@href")
  File "/home/aevans/wikiProject/venv/lib/python3.6/site-packages/selenium/webdriver/remote/webdriver.py", line 410, in find_elements_by_xpath
    return self.find_elements(by=By.XPATH, value=xpath)
  File "/home/aevans/wikiProject/venv/lib/python3.6/site-packages/selenium/webdriver/remote/webdriver.py", line 1007, in find_elements
    'value': value})['value'] or []
  File "/home/aevans/wikiProject/venv/lib/python3.6/site-packages/selenium/webdriver/remote/webdriver.py", line 321, in execute
    self.error_handler.check_response(response)
  File "/home/aevans/wikiProject/venv/lib/python3.6/site-packages/selenium/webdriver/remote/errorhandler.py", line 242, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.InvalidSelectorException: Message: invalid selector: The result of the xpath expression "//div[@id='index__tree']//a[contains(text(),doku.php)]/@href" is: [object Attr]. It should be an element.
  (Session info: headless chrome=73.0.3683.86)
  (Driver info: chromedriver=73.0.3683.86,platform=Linux 3.10.0-957.12.2.el7.x86_64 x86_64)

Answer 1

尝试替换

a = driver.find_elements_by_xpath("//div[@id='index__tree']//a[contains(text(),doku.php)]/@href")
for aa in a:
    print(aa)

与

a = [elem.get_attribute("href") for elem in driver.find_elements_by_xpath("//div[@id='index__tree']//a[contains(text(),doku.php)]")]

for aa in a:
    print(aa)

请注意，我从您的选择器末尾删除了“/@href”。

Selenium 选择器必须返回一个 WebElement。通过指定“/@href”，它返回了该元素的 href 属性，而不是元素本身。

get_attribute(attribute_name) 方法返回元素的属性。然后，你可以循环遍历它。