在python中使用scrapy执行Javascript提交表单函数

Question

我正在使用scrapy 框架废弃一个网站，并且在单击一个javascript 链接以打开另一个页面时遇到问题。

我可以将页面上的代码识别为：

<a class="Page" alt="Click to view job description" title="Click to view job description" href="javascript:sysSubmitForm('frmSR1');">Accountant&nbsp;</a>

谁能建议我如何在 scaroy 中执行该 javascript 并通过我可以从该页面获取数据来获取另一个页面。

提前致谢

Answer 1

查看以下关于如何将 scrapy 与 selenium 一起使用的片段。由于您不仅下载了 html，而且您将获得对 DOM 的完全访问权限，因此抓取速度会变慢。

注意：我已经复制粘贴了这个 sn-p，因为之前提供的链接不再有效。

# Snippet imported from snippets.scrapy.org (which no longer works)

from scrapy.contrib.spiders import CrawlSpider, Rule
from scrapy.contrib.linkextractors.sgml import SgmlLinkExtractor
from scrapy.selector import HtmlXPathSelector
from scrapy.http import Request

from selenium import selenium

class SeleniumSpider(CrawlSpider):
    name = "SeleniumSpider"
    start_urls = ["http://www.domain.com"]

    rules = (
        Rule(SgmlLinkExtractor(allow=('\.html', )),
        callback='parse_page',follow=True),
    )

    def __init__(self):
        CrawlSpider.__init__(self)
        self.verificationErrors = []
        self.selenium = selenium("localhost", 4444, "*chrome", "http://www.domain.com")
        self.selenium.start()

    def __del__(self):
        self.selenium.stop()
        print self.verificationErrors
        CrawlSpider.__del__(self)

    def parse_page(self, response):
        item = Item()

        hxs = HtmlXPathSelector(response)
        #Do some XPath selection with Scrapy
        hxs.select('//div').extract()

        sel = self.selenium
        sel.open(response.url)

        #Wait for javscript to load in Selenium
        time.sleep(2.5)

        #Do some crawling of javascript created content with Selenium
        sel.get_text("//div")
        yield item

Answer 2

如果你想查看一个相当庞大的功能代码库，它使用了 scrapy 和 selenium，请查看 https://github.com/nicodjimenez/bus_catchers。这是一个更简单的例子。

# stripped down BoltBus script 
from selenium import webdriver
from selenium.common.exceptions import TimeoutException
from selenium.webdriver.support.ui import WebDriverWait 
from selenium.webdriver.support import expected_conditions as EC
from selenium.webdriver.common.keys import Keys
from scrapy.selector import HtmlXPathSelector
from scrapy.http import Response 
from scrapy.http import TextResponse 
import time

# set dates, origin, destination 
cityOrigin="Baltimore"
cityDeparture="New York"
day_array=[0]
browser = webdriver.Firefox()

# we are going the day of the days of the month from 15,16,...,25
# there is a discrepancy between the index of the calendar days and the day itself: for example day[10] may correspond to Feb 7th
for day in day_array:

    # Create a new instance of the Firefox driver
    browser.get("http://www.boltbus.com")

    # click on "region" tab
    elem_0=browser.find_element_by_id("ctl00_cphM_forwardRouteUC_lstRegion_textBox")
    elem_0.click()
    time.sleep(5) 

    # select Northeast
    elem_1=browser.find_element_by_partial_link_text("Northeast")
    elem_1.click()
    time.sleep(5)

    # click on origin city
    elem_2=browser.find_element_by_id("ctl00_cphM_forwardRouteUC_lstOrigin_textBox")
    elem_2.click()
    time.sleep(5)

    # select origin city
    elem_3=browser.find_element_by_partial_link_text(cityOrigin)
    elem_3.click()
    time.sleep(5)

    # click on destination city 
    elem_4=browser.find_element_by_id("ctl00_cphM_forwardRouteUC_lstDestination_textBox")
    elem_4.click()
    time.sleep(5)

    # select destination city 
    elem_5=browser.find_element_by_partial_link_text(cityDeparture)
    elem_5.click()
    time.sleep(5)

    # click on travel date
    travel_date_elem=browser.find_element_by_id("ctl00_cphM_forwardRouteUC_imageE")
    travel_date_elem.click()    

    # gets day rows of table
    date_rows=browser.find_elements_by_class_name("daysrow") 

    # select actual day (use variable day)
    # NOTE: you must make sure these day elements are "clickable"
    days=date_rows[0].find_elements_by_xpath("..//td")
    days[day].click()
    time.sleep(3) 

    # retrieve actual departure date from browser
    depart_date_elem=browser.find_element_by_id("ctl00_cphM_forwardRouteUC_txtDepartureDate")
    depart_date=str(depart_date_elem.get_attribute("value"))

    # PARSE TABLE

    # convert html to "nice format"
    text_html=browser.page_source.encode('utf-8')
    html_str=str(text_html)

    # this is a hack that initiates a "TextResponse" object (taken from the Scrapy module)
    resp_for_scrapy=TextResponse('none',200,{},html_str,[],None)

    # takes a "TextResponse" object and feeds it to a scrapy function which will convert the raw HTML to a XPath document tree
    hxs=HtmlXPathSelector(resp_for_scrapy)

    # the | sign means "or"
    table_rows=hxs.select('//tr[@class="fareviewrow"] | //tr[@class="fareviewaltrow"]')
    row_ct=len(table_rows)

    for x in xrange(row_ct):

        cur_node_elements=table_rows[x]
        travel_price=cur_node_elements.select('.//td[@class="faresColumn0"]/text()').re("\d{1,3}\.\d\d")

        # I use a mixture of xpath selectors to get me to the right location in the document, and regular expressions to get the exact data

        # actual digits of time 
        depart_time_num=cur_node_elements.select('.//td[@class="faresColumn1"]/text()').re("\d{1,2}\:\d\d")

        # AM or PM (time signature)
        depart_time_sig=cur_node_elements.select('.//td[@class="faresColumn1"]/text()').re("[AP][M]")

        # actual digits of time 
        arrive_time_num=cur_node_elements.select('.//td[@class="faresColumn2"]/text()').re("\d{1,2}\:\d\d")

        # AM or PM (time signature)
        arrive_time_sig=cur_node_elements.select('.//td[@class="faresColumn2"]/text()').re("[AP][M]")

        print "Depart date: " + depart_date
        print "Depart time: " + depart_time_num[0] + " " + depart_time_sig[0]   
        print "Arrive time: " + arrive_time_num[0] + " " + arrive_time_sig[0]
        print "Cost: " + "$" + travel_price[0] 
        print "\n"

Answer 3

据我所知，通过 urrlib2 和 urllib 实现的 scrappy 爬虫显然不适用于 js。例如，对于使用 js，您可以使用 qt webkit 或 selenium。或者您可以在页面上找到所有 ajax 链接，并查看如何实现与服务器的数据交换并间接向服务器 api 发送响应。