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Jan 21
2010

Writing a spider in 10 mins using Scrapy digg

I came across Scrapy a few days back and have grown to really love it. This tutorial will illustrate how you can write a simple spider using Scrapy to scrape data off Paul Smith. All this in 10 minutes.

Lets begin

  1. Download and install scrapy and its dependencies.
  2. This done, open up your terminal and type python scrapy-ctl.py startproject paul_smith. A scrapy project will be created.
  3. Navigate to ~/paul_smith/paul_smith/spiders and create the file paul_smith.py with the following contents:

    paul_smith.py
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    from scrapy.spider import BaseSpider
     
    class PaulSmithSpider(BaseSpider):
      domain_name = "paulsmith.co.uk"
      start_urls = ["http://www.paulsmith.co.uk/paul-smith-jeans-253/category.html"]
     
      def parse(self, response):
        open('paulsmith.html', 'wb').write(response.body)
     
    SPIDER = PaulSmithSpider()
  4. To run the spider, go to ~/paul_smith type python scrapy-ctl.py crawl paulsmith.co.uk on the command line. This will fetch the page and save it to paulsmith.html.
  5. The next step is to parse the contents of the page. Open the page in your favourite editor and try to understand the pattern of the items we want to capture. You can see that <div class="yui-u"> contains the required information. We are going to modify out code like so:

    paul_smith.py
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    from scrapy.spider import BaseSpider
    from scrapy.selector import HtmlXPathSelector
     
    class PaulSmithSpider(BaseSpider):
      domain_name = "paulsmith.co.uk"
      start_urls = ["http://www.paulsmith.co.uk/paul-smith-jeans-253/category.html"]
     
      def parse(self, response):
        hxs = HtmlXPathSelector(response)
        sites = hxs.select('//div[@class="yui-u"]')
        for site in sites:
          print site.extract()
     
    SPIDER = PaulSmithSpider()

    You can read more on XPath Selectors here.

  6. Finally, looking at the HTML again, we can extract title, link, img-src & sale-price like so:

    paul_smith.py
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    from scrapy.spider import BaseSpider
    from scrapy.selector import HtmlXPathSelector
    import random
     
    class PaulSmithSpider(BaseSpider):
      domain_name = "paulsmith.co.uk"
      start_urls = ["http://www.paulsmith.co.uk/paul-smith-jeans-253/category.html"]
     
      def parse(self, response):
        hxs = HtmlXPathSelector(response)
        sites = hxs.select('//div[@class="yui-u"]')
        random.shuffle(sites)
        for site in sites:
          title = site.select('a/strong[@class="thumbnail-text"]/text()').extract()
          hlink = site.select('a/@href').extract()
          price = site.select('a/strong[@class="sale"]/text()').extract()
          image = site.select('a/img/@src').extract()
     
          print title, hlink, image, price
     
    SPIDER = PaulSmithSpider()

    You can save this data to your datastore in whatever way you wish.

  7. The output of 3 random items scraped using the above code can be seen below.

Output

Shawl Collar Block Stripe Jumper
Sale: £ 74.00

Crew Neck Placement Stripe Jumper
Sale: £ 67.00

Tailored Fit, Organic Cotton Cravat Print Shirt
Sale: £ 74.00

One Response (rss) (trackback)

#1

Jens

March 3rd, 2010 at 10:00 pm

Hi
Trying out your tutorial but it seems like Paul Smith has made some changes to the site. I wonder if you can update you code above so it works. I’m just trying this out and a good example would be great! Keep up the good work. /Jens

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