WebDriverWait语法错误

Question

运行OS X和Python 3.5.1。

只是想知道WebDriverWait搜索xpath的适当上下文是什么，然后在加载包含的网页后继续单击它。

WebDriverWait(driver, 10000).until(EC.presence_of_element_located(driver.find_element_by_xpath(".//*[@id='maincontent']/section[2]/div[1]/table/tbody/tr[1]/td[7]/button")))
a = driver.find_element_by_xpath(".//*[@id='maincontent']/section[2]/div[1]/table/tbody/tr[1]/td[7]/button")
a.click()

错误码如下

Traceback (most recent call last):
  File "/Users/hansh/Desktop/markets.py", line 22, in <module>
    WebDriverWait(driver, 10000).until(EC.presence_of_element_located(driver.find_element_by_xpath(".//*[@id='maincontent']/section[2]/div[1]/table/tbody/tr[1]/td[7]/button")))
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/selenium/webdriver/remote/webdriver.py", line 258, in find_element_by_xpath
    return self.find_element(by=By.XPATH, value=xpath)
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/selenium/webdriver/remote/webdriver.py", line 712, in find_element
    {'using': by, 'value': value})['value']
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/selenium/webdriver/remote/webdriver.py", line 201, in execute
    self.error_handler.check_response(response)
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/selenium/webdriver/remote/errorhandler.py", line 181, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.NoSuchElementException: Message: Unable to locate element: {"method":"xpath","selector":".//*[@id='maincontent']/section[2]/div[1]/table/tbody/tr[1]/td[7]/button"}
Stacktrace:
    at FirefoxDriver.prototype.findElementInternal_ (file:///var/folders/b3/h2pq8lmx4p11tb5h3m49xbth0000gn/T/tmpb9uhnk6f/extensions/fxdriver@googlecode.com/components/driver-component.js:10659)
    at FirefoxDriver.prototype.findElement (file:///var/folders/b3/h2pq8lmx4p11tb5h3m49xbth0000gn/T/tmpb9uhnk6f/extensions/fxdriver@googlecode.com/components/driver-component.js:10668)
    at DelayedCommand.prototype.executeInternal_/h (file:///var/folders/b3/h2pq8lmx4p11tb5h3m49xbth0000gn/T/tmpb9uhnk6f/extensions/fxdriver@googlecode.com/components/command-processor.js:12534)
    at DelayedCommand.prototype.executeInternal_ (file:///var/folders/b3/h2pq8lmx4p11tb5h3m49xbth0000gn/T/tmpb9uhnk6f/extensions/fxdriver@googlecode.com/components/command-processor.js:12539)
    at DelayedCommand.prototype.execute/< (file:///var/folders/b3/h2pq8lmx4p11tb5h3m49xbth0000gn/T/tmpb9uhnk6f/extensions/fxdriver@googlecode.com/components/command-processor.js:12481)

Answer 1

根据documentation，正确的语法是一个元组，其中第一个元素是定位器类型，第二个是定位器值。按如下方式重写：

from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC    

wait = WebDriverWait(driver, 10)
presence_of = EC.presence_of_element_located
wait.until(presence_of((By.XPATH, ".//*[@id='maincontent']/section[2]/div[1]/table/tbody/tr[1]/td[7]/button")))

另外，请注意，您传递给WebDriverWait构造函数的超时值是以秒为单位的，而不是毫秒。您可能指的是10而不是10000。