WebDriverException:消息:使用safaridriver和Selenium 3.13.0进行显式等待时找不到命令'GET /session/7.../displayed'

Question

我正在使用下面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")))

但我得到错误

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

如果我使用time.sleep()它工作正常而不是explicir等待它工作正常.我已经初始化了safari驱动程序

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

这个错误信息...

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

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

显示的元素

根据WebDriver W3C 编辑器的草案，元素显示算法是一个布尔状态，其中true表示元素已显示，false表示元素未显示。要计算元素上的状态，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。否则返回错误代码为 unknown error 的错误。

此函数通常暴露给具有 URI 模板的 GET 请求

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

分析

您已调用：

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

element_to_be_clickable()类在内部调用visibility_of_element_located()并定义为：

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()类返回_element_if_visible(_find_element(driver, self.locator))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

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

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

因此，作为失败的if()条件，您会看到错误为对端点的请求失败。element.is_displayed() == visibility GET/session/{session id}/element/{element id}/displayed

如果没有相关的HTML和前面的步骤，很难猜测确切原因，但可能是以下任一原因：

原因

NoSuchElementException的原因可能是以下之一：

• 您采用的定位器策略不识别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不会在HTML DOM 中唯一标识所需元素，并且当前会找到一些其他隐藏/不可见元素。
• 您尝试定位的WebElement位于<iframe>标记内。

解决方案

解决NoSuchElementException的解决方案可以是以下之一：

• 采用唯一标识所需WebElement的定位器策略。你可以采取的帮助开发者工具（+ +或），并使用元素督察。CtrlShiftIF12

  在这里，您将找到有关如何检查 selenium3.6 中的元素的详细讨论，因为萤火虫不再是 FF 56 的选项？

• 使用execute_script()方法滚动元素查看如下：

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

  在这里，您将找到有关使用 Selenium 在 Python 中滚动到页面顶部的详细讨论

• Incase 元素具有属性style="display: none;" ，通过executeScript()方法删除属性如下：

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

• 要检查元素是否在HTML 中<iframe>向上遍历以通过以下任一方法定位相应的标记和所需的iframe：<iframe>switchTo()

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

  在这里你可以找到关于如何选择一个 html 元素无论它在 selenium 中的哪个框架的详细讨论？.