title: Order of iterations in start urls scrapy
body: <p>I have a list of urls in a csv file, I load this file in a pandas data frame, and use the column links as start urls</p>
  
  <pre><code>start_urls =  df['Links']
  </code></pre>
  
  <p>each link have this format</p>
  
  <pre><code>http://www.bbb.org/search/?type=name&amp;input=%28408%29+998-0983&amp;location=&amp;tobid=&amp;filter=business&amp;radius=&amp;country=USA%2CCAN&amp;language=en&amp;codeType=YPPA
  </code></pre>
  
  <p>this link is related with a phone number (408) 998-0983 which apears in the link as %28408%29+998-0983</p>
  
  <p>for each of the pages in <code>df['Links']</code> I scrap some data, and save it in an item, so far so good, the problem I have is that the order in wich scrapy takes the list is not the same  that is is the data frame, so I can't merge the data I get with scrapy and the file that I already have becauses the rows doesn't match, also I would like to handle the exception when the page doesn't have the data an return a string, in wich part of the code could I do that, this is what I'm doing right now:</p>
  
  <pre><code>def parse(self, response):
  
  
  
  
      producto = Product()
      producto = Product(BBB_link = response.xpath('//*[@id="container"]/div/div[1]/div[3]/table/tbody/tr[1]/td/h4[1]/a').extract()
  </code></pre>