Ejecutando Javascript Presentar funciones de formulario usando scrapy en python

Question

Estoy eliminando un sitio usando el framework scrapy y teniendo problemas para hacer clic en un enlace javascript para abrir otra página.

que puede identificar el código de la página como:

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

me puede sugerir cualquiera que la forma de ejecutar javascript en scaroy y obtener a través de otra página que puedo obtener los datos de esa página.

Gracias de antemano

Answer 1

Pagar la siguiente información sobre cómo usar scrapy con selenio. El rastreo será más lento ya que no solo está descargando el html, sino que tendrá acceso completo al DOM.

Nota: He copiado y pegado este fragmento porque los enlaces proporcionados anteriormente ya no funcionan.

# 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

Por lo que yo sé, rastreador rudimentario implementado sobre urrlib2 y urllib, obviamente, no trabajan con js. Para trabajar con js puedes usar qt webkit o selenio por ejemplo. O bien, podría encontrar todos los enlaces ajax en la página y ver cómo se implementó un intercambio de datos con el servidor y enviar respuesta al API del servidor indirectamente.

Answer 3

Si quieres echa un vistazo a una enorme base bastante, código funcional que utiliza scrapy y selenio, echa un vistazo a https://github.com/nicodjimenez/bus_catchers. Aquí hay un ejemplo más simple.

# 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"