title: collect <select><option> values with Scrapy
body: <p>I pretend crawl every item in  of the drop-down list in the top of this page: <a href="https://www.anmp.pt/anmp/pro/mun1/mun101w3.php?cod=M2200" rel="nofollow noreferrer">https://www.anmp.pt/anmp/pro/mun1/mun101w3.php?cod=M2200</a> with Scrapy framework.
  Then for every item found I get a new page, where I get some more data that must fill the models instantiated in Models.py
  I can get the data, but I have been unable to put it in the flask.Fields() of my model. I searched in the web for hints but no success. 
  The field "contacto" in the spider is just to collect the other two fields after:</p>
  
  <p>Sorry the names are in portuguese, but it is a portuguese app!</p>
  
  <p>This is my Spider.py:</p>
  
  <pre><code># -*- coding: utf-8 -*-
  import scrapy
  import urlparse
  from scrapy.http import FormRequest
  from scrapy.loader import ItemLoader
  from municipios.items import Municipio
  import time
  
  
  class GetmunSpider(scrapy.Spider):
      name = 'getMun'
      allowed_domains = ['anmp.pt']
      start_urls = ['https://www.anmp.pt/anmp/pro/mun1/mun101w3.php?cod=M2200']
  
      def municipio_attr(self, response):
          municipios_url = response.xpath('//select/option/@value').extract()
          for municipio in municipios_url:
              full_url = ['https://www.anmp.pt/anmp/pro/mun1/{0}'.format(i) for i in municipios_url]      
              yield FormRequest.from_response(str(full_url), callback=self.parse) 
  
      def parse(self, response):
          #dados do municipio
          municipio = ItemLoader(item = Municipio(), response = response)
          municipio.add_xpath('nome', '//div[@class="sel3"]/text()'.extract())    
          municipio.add_xpath('pres_camara','//div[@class="f3"]/text()'
                   [3].extract().split(",")[0]
          municipio.add_xpath('pres_assembleia','//div[@class="f3"]/text()'
                   [4].extract().split(",")[0]
          municipio.add_xpath('contacto','//div[@class="sel2"]/text(
                   )').extract()
          municipio.add_value('endereco', " ".join(contacto)[:-42])
          municipio.add_value('telefone', contacto[2])
          municipio.add_value('fax', contacto[3])
  
          return Municipio.load_item()
  </code></pre>
  
  <p>And these are the fields to populate:</p>
  
  <pre><code>import scrapy
  from scrapy.item import Item, Field
  
  class Municipio(scrapy.Item):
      nome = scrapy.Field()
      pres_camara = scrapy.Field()
      pres_assembleia = scrapy.Field()
      endereco = scrapy.Field()
      telefone = scrapy.Field()
      fax = scrapy.Field()
  </code></pre>