标签:drive exception 执行 mod src res iterable ret otv
很多 case 在运行时都会出现页面还没加载完成,但是脚本已经跑完,并且报未找到元素
这是就需要增加判断,在预定的时间内如果页面显示了某元素后再让脚本继续执行,则为判断元素是否可见或者说页面是否显示了某元素
以百度首页,搜素框为例:
from selenium import webdriver from selenium.webdriver.support import expected_conditions as EC driver = webdriver.Chrome() driver.get(‘https://www.baidu.com/‘) baidu_input = driver.find_element_by_id(‘kw‘) EC.visibility_of_element_located(baidu_input) driver.close()
EC.visibility_of_element_located(baidu_input) 只是判断元素是否可见,若果这样写明显存在不合理的地方。如果代码运行很快,页面还未加载完就会出现该元素可见找不到。
所以通常需要结合 WebDriverWait 一起使用
from selenium import webdriver from selenium.webdriver.support import expected_conditions as EC from selenium.webdriver.support.wait import WebDriverWait from selenium.webdriver.common.by import By driver = webdriver.Chrome() driver.get(‘https://www.baidu.com/‘) baidu_input = (By.ID, ‘kw‘) WebDriverWait(driver,10).until(EC.visibility_of_element_located(baidu_input)) driver.close()
查看 WebDriverWait 类,他需要传入driver,超时时间timeout,而 unit 只需要传入定位元素,如下代码 WebDriverWait 类所示
所以在使用 WebDriverWait 时需要对元素定位使用 By 定位,剔除通过 driver 再定位的方法,如上代码所示
WebDriverWait 类
# Licensed to the Software Freedom Conservancy (SFC) under one # or more contributor license agreements. See the NOTICE file # distributed with this work for additional information # regarding copyright ownership. The SFC licenses this file # to you under the Apache License, Version 2.0 (the # "License"); you may not use this file except in compliance # with the License. You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, # software distributed under the License is distributed on an # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY # KIND, either express or implied. See the License for the # specific language governing permissions and limitations # under the License. import time from selenium.common.exceptions import NoSuchElementException from selenium.common.exceptions import TimeoutException POLL_FREQUENCY = 0.5 # How long to sleep inbetween calls to the method IGNORED_EXCEPTIONS = (NoSuchElementException,) # exceptions ignored during calls to the method class WebDriverWait(object): def __init__(self, driver, timeout, poll_frequency=POLL_FREQUENCY, ignored_exceptions=None): """Constructor, takes a WebDriver instance and timeout in seconds. :Args: - driver - Instance of WebDriver (Ie, Firefox, Chrome or Remote) - timeout - Number of seconds before timing out - poll_frequency - sleep interval between calls By default, it is 0.5 second. - ignored_exceptions - iterable structure of exception classes ignored during calls. By default, it contains NoSuchElementException only. Example: from selenium.webdriver.support.ui import WebDriverWait \n element = WebDriverWait(driver, 10).until(lambda x: x.find_element_by_id("someId")) \n is_disappeared = WebDriverWait(driver, 30, 1, (ElementNotVisibleException)).\ \n until_not(lambda x: x.find_element_by_id("someId").is_displayed()) """ self._driver = driver self._timeout = timeout self._poll = poll_frequency # avoid the divide by zero if self._poll == 0: self._poll = POLL_FREQUENCY exceptions = list(IGNORED_EXCEPTIONS) if ignored_exceptions is not None: try: exceptions.extend(iter(ignored_exceptions)) except TypeError: # ignored_exceptions is not iterable exceptions.append(ignored_exceptions) self._ignored_exceptions = tuple(exceptions) def __repr__(self): return ‘<{0.__module__}.{0.__name__} (session="{1}")>‘.format( type(self), self._driver.session_id) def until(self, method, message=‘‘): """Calls the method provided with the driver as an argument until the return value is not False.""" screen = None stacktrace = None end_time = time.time() + self._timeout while True: try: value = method(self._driver) if value: return value except self._ignored_exceptions as exc: screen = getattr(exc, ‘screen‘, None) stacktrace = getattr(exc, ‘stacktrace‘, None) time.sleep(self._poll) if time.time() > end_time: break raise TimeoutException(message, screen, stacktrace) def until_not(self, method, message=‘‘): """Calls the method provided with the driver as an argument until the return value is False.""" end_time = time.time() + self._timeout while True: try: value = method(self._driver) if not value: return value except self._ignored_exceptions: return True time.sleep(self._poll) if time.time() > end_time: break raise TimeoutException(message)
元素是否可见的方法
visibility_of_element_located : 判断某个元素是否可见
invisibility_of_element_located : 判断某个元素是否不存在或不可见
visibility_of : 判断元素是否可见,通过 driver 查找元素,如:EC.visibility_of(driver.find_element_by_id(‘kw‘))
visibility_of_all_elements_located() :判断定位的所有元素都存在于DOM树中并且可见,可存在则以list形式返回
visibility_of_any_elements_located() : 判断定位的所有元素中,至少有一个存在于DOM树中并且可见,list形式返回存在的元素
标签:drive exception 执行 mod src res iterable ret otv
原文地址:https://www.cnblogs.com/tynam/p/10343145.html