Spidey provides a bare-bones framework for crawling and scraping web sites. Its goal is to keep boilerplate scraping logic out of your code.
This example spider crawls an eBay page, follows links to category pages, continues to auction detail pages, and finally records a few scraped item details as a result.
class EbayPetSuppliesSpider < Spidey::AbstractSpider
handle "http://pet-supplies.shop.ebay.com", :process_home
def process_home(page, default_data = {})
page.search("#AllCats a[role=menuitem]").each do |a|
handle resolve_url(a.attr('href'), page), :process_category, category: a.text.strip
end
end
def process_category(page, default_data = {})
page.search("#ResultSetItems table.li td.dtl a").each do |a|
handle resolve_url(a.attr('href'), page), :process_auction, default_data.merge(title: a.text.strip)
end
end
def process_auction(page, default_data = {})
image_el = page.search('div.vi-ipic1 img').first
price_el = page.search('span[itemprop=price]').first
record default_data.merge(
image_url: (image_el.attr('src') if image_el),
price: price_el.text.strip
)
end
end
spider = EbayPetSuppliesSpider.new verbose: true
spider.crawl max_urls: 100
spider.results # => [{category: "Aquarium & Fish", title: "5 Gal. Fish Tank"...
Implement a spider class extending Spidey::AbstractSpider
for each target site. The class can declare starting URLs by calling handle
at the class level. Spidey invokes each of the methods specified in those calls, passing in the resulting page
(a Mechanize Page object) and, optionally, some scraped data. The methods can do whatever processing of the page is necessary, calling handle
with additional URLs to crawl and/or record
with scraped results.
By default, the lists of URLs being crawled, results scraped, and errors encountered are stored as simple arrays in the spider (i.e., in memory):
spider.urls # => ["http://www.ebay.com", "http://www.ebay.com/...", ...]
spider.results # => [{auction_title: "...", sale_price: "..."}, ...]
spider.errors # => [{url: "...", handler: :process_home, error: FooException}, ...]
Add the spidey-mongo gem and include Spidey::Strategies::Mongo
in your spider to instead use MongoDB to persist these data. See the docs for more information. Or, you can implement your own strategy by overriding the appropriate methods from AbstractSpider
.
Spidey is very much a work in progress. Pull requests welcome.
- Spidey works well for crawling public web pages, but since little effort is undertaken to preserve the crawler's state across requests, it works less well when particular cookies or sequences of form submissions are required. Mechanize supports this quite well, though, so Spidey could grow in that direction.
Copyright (c) 2012 Joey Aghion, Art.sy Inc. See LICENSE.txt for further details.