title: Getting error in scrapy web crawler
body: <p>Hi I tried to implement this in my code.But I am getting the following error: <code>exceptions.NameError: global name 'Request' is not defined</code>.</p>
  
  <pre><code>from scrapy.spider import BaseSpider
  from scrapy.selector import HtmlXPathSelector 
  from bs4 import BeautifulSoup
  
  class spider_aicte(BaseSpider):
      name = "Indian_Colleges"
      allowed_domains = ["http://www.domain.org"]
      start_urls = [
          "http://www.domain.org/appwebsite.html",
          ]
  
      def parse(self, response):
          filename = response.url.split("/")[-2]
          soup = BeautifulSoup(response.body)
          for link in soup.find_all('a'):
              download_link = link.get('href')
              if '.pdf' in download_link:
                  pdf_link = "http://www.domain.org" + download_link
                  print pdf_link
                  class FileSpider(BaseSpider):
                      name = "fspider"
                      allowed_domains = ["www.domain.org"]
                      start_urls = [
                              pdf_link
                              ]
          for url in pdf_link:
              yield Request(url, callback=self.save_pdf)
  
      def save_pdf(self, response):
           path = self.get_path(response.url)
           with open(path, "wb") as f:
              f.write(response.body)
  </code></pre>