python - WebDriver异常: Message: The command 'GET/session/7.../displayed' was not found while Explicit Wait with safaridriver and Selenium 3. 13.0

Question

我正在使用如下所示的显式等待来检查元素是否可点击。

WebDriverWait(driver, 30).until(
        expected_conditions.element_to_be_clickable((By.CSS_SELECTOR, "#search")))

但是我收到错误

 <class 'selenium.common.exceptions.WebDriverException'>
Message: The command 'GET /session/.../displayed' was not found.

如果我使用time.sleep()，它可以正常工作，而不是明确的等待，它可以正常工作。我已将 safari 驱动程序初始化为

from selenium.webdriver import Safari
driver = Safari()

这是堆栈跟踪

  File "/Users/Library/Python/2.7/lib/python/site-packages/selenium/webdriver/support/wait.py", line 71, in until
    value = method(self._driver)
  File "/Users/Library/Python/2.7/lib/python/site-packages/selenium/webdriver/support/expected_conditions.py", line 283, in __call__
    element = visibility_of_element_located(self.locator)(driver)
  File "/Users/Library/Python/2.7/lib/python/site-packages/selenium/webdriver/support/expected_conditions.py", line 127, in __call__
    return _element_if_visible(_find_element(driver, self.locator))
  File "/Users/Library/Python/2.7/lib/python/site-packages/selenium/webdriver/support/expected_conditions.py", line 147, in _element_if_visible
    return element if element.is_displayed() == visibility else False
  File "/Users/Library/Python/2.7/lib/python/site-packages/selenium/webdriver/remote/webelement.py", line 490, in is_displayed
    return self._execute(Command.IS_ELEMENT_DISPLAYED)['value']
  File "/Users/Library/Python/2.7/lib/python/site-packages/selenium/webdriver/remote/webelement.py", line 628, in _execute
    return self._parent.execute(command, params)
  File "/Users/Library/Python/2.7/lib/python/site-packages/selenium/webdriver/remote/webdriver.py", line 314, in execute
    self.error_handler.check_response(response)
  File "/Users/Library/Python/2.7/lib/python/site-packages/selenium/webdriver/remote/errorhandler.py", line 242, in check_response
    raise exception_class(message, screen, stacktrace)
WebDriverException: Message: The command 'GET /session/7.../displayed' was not found.

Answer 1

此错误消息...

 <class 'selenium.common.exceptions.WebDriverException'>
Message: The command 'GET /session/.../displayed' was not found.

...意味着 GET 请求 /session/{session id}/element/{element id}/displayed失败。

<小时/>

显示元素

根据 WebDriver W3C Editor's Draft element displayed算法是一个 bool 状态，其中 true表示该元素已显示并且 false表示该元素不显示。要计算元素的状态，请调用 Call(bot.dom.isShown, null, element) 。如果这样做不会产生错误，则返回此函数调用的返回值。否则返回错误，并带有错误代码未知错误。

此函数通常会暴露给 URI 模板为

的 GET 请求

/session/{session id}/element/{element id}/displayed

<小时/>

分析

您已调用:

WebDriverWait(driver, 30).until(expected_conditions.element_to_be_clickable((By.CSS_SELECTOR, "#search")))

element_to_be_clickable()类内部调用 visibility_of_element_located()定义为:

class element_to_be_clickable(object):
    """ An Expectation for checking an element is visible and enabled such that you can click it."""
    def __init__(self, locator):
    self.locator = locator

    def __call__(self, driver):
    element = visibility_of_element_located(self.locator)(driver)
    if element and element.is_enabled():
        return element
    else:
        return False

现在，visibility_of_element_located()类(class)返回_element_if_visible(_find_element(driver, self.locator))其定义为:

class visibility_of_element_located(object):
    """ An expectation for checking that an element is present on the DOM of a
    page and visible. Visibility means that the element is not only displayed
    but also has a height and width that is greater than 0.
    locator - used to find the element
    returns the WebElement once it is located and visible
    """
    def __init__(self, locator):
    self.locator = locator

    def __call__(self, driver):
    try:
        return _element_if_visible(_find_element(driver, self.locator))
    except StaleElementReferenceException:
        return False

再次，_element_if_visible()返回element if element.is_displayed() == visibility else False其定义为:

def _element_if_visible(element, visibility=True):
    return element if element.is_displayed() == visibility else False

所以，如 if() element.is_displayed() == visibility的状况失败，因此您会看到错误为 GET向 /session/{session id}/element/{element id}/displayed 请求 端点失败。

如果没有相关的 HTML 和之前的步骤，很难猜测确切的原因，但可能是以下任一原因:

<小时/>

原因

NoSuchElementException 的原因可能是以下任一原因:

• 您采用的定位器策略未识别 HTML DOM 中的任何元素.
• 您采用的定位器策略无法识别该元素，因为它不在浏览器的 Viewport 内.
• 您采用的定位器策略标识了该元素，但由于属性style="display: none;"的存在而不可见。
• 您采用的定位器策略无法唯一标识HTML DOM中所需的元素，并且当前会找到一些其他隐藏/不可见元素。
• 您尝试查找的WebElement位于 <iframe> 内标签。

<小时/>

解决方案

解决NoSuchElementException的解决方案可以是以下任一:

• 采用Locator Strategy它唯一标识所需的WebElement。您可以借助开发人员工具(Ctrl+Shift+I 或 F12)并使用元素检查器。

  在这里您可以找到关于 how to inspect element in selenium3.6 as firebug is not an option any more for FF 56? 的详细讨论

• 使用 execute_script() 滚动元素查看的方法如下:

  elem = driver.find_element_by_xpath("element_xpath")
  driver.execute_script("arguments[0].scrollIntoView();", elem)
  

  在这里您可以找到关于 Scrolling to top of the page in Python using Selenium 的详细讨论

• 如果元素具有属性style="display: none;"，请通过 executeScript() 删除该属性方法如下:

  elem = driver.find_element_by_xpath("element_xpath")
  driver.execute_script("arguments[0].removeAttribute('style')", elem)
  elem.send_keys("text_to_send")
  

• 检查元素是否在 <iframe> 内向上遍历 HTML 以找到相应的 <iframe>标签和switchTo()通过以下任一方法获取所需的iframe:

  driver.switch_to.frame("iframe_name")
  driver.switch_to.frame("iframe_id")
  driver.switch_to.frame(1) // 1 represents frame index
  

  在这里您可以找到关于 How can I select a html element no matter what frame it is in in selenium? 的详细讨论.