Python Can'；无法访问WebElement

我第一次尝试获取元素时出错。请注意，我第二次尝试时，它确实有效。这是一个调试会话：

>>> self.selenium.find_element_by_xpath('//*[@id="add-button"]')
Traceback (most recent call last):
  File "/home/vagrant/.pycharm_helpers/pydev/pydevd_exec2.py", line 3, in Exec
    exec(exp, global_vars, local_vars)
  File "<input>", line 1, in <module>
  File "/vagrant/venv/lib/python3.4/site-packages/selenium/webdriver/remote/webdriver.py", line 232, in find_element_by_xpath
    return self.find_element(by=By.XPATH, value=xpath)
  File "/vagrant/venv/lib/python3.4/site-packages/selenium/webdriver/remote/webdriver.py", line 664, in find_element
    {'using': by, 'value': value})['value']
  File "/vagrant/venv/lib/python3.4/site-packages/selenium/webdriver/remote/webdriver.py", line 173, in execute
    response = self.command_executor.execute(driver_command, params)
  File "/vagrant/venv/lib/python3.4/site-packages/selenium/webdriver/remote/remote_connection.py", line 349, in execute
    return self._request(command_info[0], url, body=data)
  File "/vagrant/venv/lib/python3.4/site-packages/selenium/webdriver/remote/remote_connection.py", line 380, in _request
    resp = self._conn.getresponse()
  File "/usr/lib/python3.4/http/client.py", line 1147, in getresponse
    response.begin()
  File "/usr/lib/python3.4/http/client.py", line 351, in begin
    version, status, reason = self._read_status()
  File "/usr/lib/python3.4/http/client.py", line 321, in _read_status
    raise BadStatusLine(line)
http.client.BadStatusLine: ''
>>> self.selenium.find_element_by_xpath('//*[@id="add-button"]')
<selenium.webdriver.remote.webelement.WebElement object at 0x7f90ab074400>

在/usr/lib/python3.4/http/client.py:319上找到此注释：

据推测，服务器在发送有效消息之前关闭了连接 答复

其他信息：

• 操作系统：Ubuntu 14.04.2 LTS
• Python:3.4.0
• Django:1.7.6
• 硒：2.45.0
• Firefox:36.0.4

---

你知道我会错过什么吗？

正如前面所说的，当Selenium出现问题时，最好更新它，同时更新firefox

在您的情况下，您确定元素确实已加载吗？我可以看到

隐式等待

方法，但加载时间可能会有所不同，因此可能不够

---

您可以从增加

隐式等待时间开始，然后再试一次。
这很奇怪。当隐式地更改
调用上的值时，我会看到奇怪的行为。有时它只是抛出我在上面粘贴的错误，有时它只是挂起：/@micgeronimo，是的。一切都是最新的：/将定位器包装在范围（3）的循环中似乎可行，但这是一个非常糟糕的解决方案：(
from selenium.webdriver.firefox.webdriver import WebDriver
from django.contrib.staticfiles.testing import StaticLiveServerTestCase
from xvfbwrapper import Xvfb

class UIPropertyTestCase(StaticLiveServerTestCase):
    fixtures = ['properties']

    @classmethod
    def setUpClass(cls):
        cls.vdisplay = Xvfb()
        cls.vdisplay.start()
        cls.selenium = WebDriver()
        cls.selenium.implicitly_wait(10)
        super(UIPropertyTestCase, cls).setUpClass()

    @classmethod
    def tearDownClass(cls):
        cls.selenium.quit()
        cls.vdisplay.stop()
        super(UIPropertyTestCase, cls).tearDownClass()

    def test_add_property(self):
        self.selenium.get('{0}{1}'.format(self.live_server_url, '/#/app/properties'))
        self.selenium.find_element_by_xpath('//*[@id="add-button"]').click()

        self.selenium.get('{0}{1}'.format(self.live_server_url, '/#/app/properties'))
        count = len(self.selenium.find_elements_by_xpath('//*[@id="data"]/tbody/tr'))
        self.assertEqual(count, 3)