python - 使用 selenium 刷新页面导致 StaleElementReferenceException 错误

Question

我有一个使用 selenium 的 python 脚本。脚本的步骤是:

1. 登录
2. 转到启动文件收集器进程的页面
3. 每 1 分钟刷新一次状态页面以检查文件收集器是否已完成 - 这会在页面上的表格中显示

我遇到的问题是，当使用 browser.refresh() 刷新页面时，我收到以下错误

Traceback (most recent call last):
  File "D:\ScheduledTasks\Scripts\ScriptArchive\COL_INSPIRE\INSPIRE_METADATA_v1.1.py", line 491, in <module>
    print head.text
  File "C:\Python27\ArcGIS10.2\lib\site-packages\selenium-2.44.0-py2.7.egg\selenium\webdriver\remote\webelement.py", line 61, in text
    return self._execute(Command.GET_ELEMENT_TEXT)['value']
  File "C:\Python27\ArcGIS10.2\lib\site-packages\selenium-2.44.0-py2.7.egg\selenium\webdriver\remote\webelement.py", line 385, in _execute
    return self._parent.execute(command, params)
  File "C:\Python27\ArcGIS10.2\lib\site-packages\selenium-2.44.0-py2.7.egg\selenium\webdriver\remote\webdriver.py", line 173, in execute
    self.error_handler.check_response(response)
  File "C:\Python27\ArcGIS10.2\lib\site-packages\selenium-2.44.0-py2.7.egg\selenium\webdriver\remote\errorhandler.py", line 166, in check_response
    raise exception_class(message, screen, stacktrace)
StaleElementReferenceException: Message: Element not found in the cache - perhaps the page has changed since it was looked up

这曾经有效，但现在出现上述错误，“轮询”页面以检查一段文本是否已更改的最佳方法是什么。

我的代码是

header = browser.find_elements(By.TAG_NAME,"tr")
#go through each header to get teh one we want
headerIndex = 0
for head in header:

 #print headerIndex
 print head.text
 if "Next harvest" in head.text:
    #Get the table data for the header that we want
    tdata = header[headerIndex].find_elements(By.TAG_NAME,"td")
    for t in tdata:
       print t.text
       if "Scheduled" in t.text:
          #wait 60 seconds
          time.sleep(60)
          browser.refresh()
       elif "Not yet scheduled" in t.text:
          refreshComplete = True
          break
 if refreshComplete == True:
    break
 headerIndex = headerIndex + 1

Answer 1

每次刷新页面时都必须找到标题。

我还会改用 find_element(s)_by_xpath 来检查文本:

while True:
    header = browser.find_element_by_xpath('//tr[contains(., "Next harvest")]')

    not_scheduled = header.find_elements_by_xpath('//td[contains(., "Not yet scheduled")]')
    if not_scheduled:
        break

    time.sleep(60)
    browser.refresh()

希望您已经了解解决方案背后的想法(但请检查我是否正确遵循了逻辑)。