title: How to get the proxy used for each request in an item with Scrapy?
body: <p>I'm using a <code>DOWNLOADER_MIDDLEWARES</code> for rotating proxies with an <code>scrapy.Spider</code> and I would like to get an item , i.e. <code>item['proxy_used']</code>,  for  the proxy used  for each request.</p>
  
  <p>I guess it could be possible to get the Proxy over the "Stats Collector"  but I'm new to Python and Scrapy and till now I haven't been able to come across with a solution.</p>
  
  <pre><code>import scrapy
  from tutorial.items import QuotesItem
  
  class QuotesSpider(scrapy.Spider):
      name = "quotes"
      allowed_domains = ["quotes.toscrape.com"]
      start_urls = [
          'http://quotes.toscrape.com/',
      ]
  
      def parse_quotes(self, response):
          for sel in response.css('div.quote'):
              item = QuotesItem()
              item['text'] = sel.css('span.text::text').get()
              item['author'] = sel.css('small.author::text').get()
              item['tags'] = sel.css('div.tags a.tag::text').getall()
              item['quotelink'] = sel.css('small.author ~ a[href*="goodreads.com"]::attr(href)').get()
  
              item['proxy_used'] = ??? &lt;-- PROXY USED BY REQUEST - "HOW TO???"
              yield item 
  
       # follow pagination links @shortcut
  
          for a in response.css('li.next a'):
              yield response.follow(a, callback = self.parse_quotes)
  </code></pre>