# This scripts shows how to crawl a site without settings up a complete project.
# 
# Note: the `crawler.start()` can't be called more than once due twisted's reactor limitation.

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# author: Rolando Espinoza La fuente
#
# Changelog:
#     24/07/2011 - updated to work with scrapy 13.0dev
#     25/08/2010 - initial version. works with scrapy 0.9

from scrapy.contrib.loader import XPathItemLoader
from scrapy.item import Item, Field
from scrapy.selector import HtmlXPathSelector
from scrapy.spider import BaseSpider


class QuestionItem(Item):
    """Our SO Question Item"""
    title = Field()
    summary = Field()
    tags = Field()

    user = Field()
    posted = Field()

    votes = Field()
    answers = Field()
    views = Field()


class MySpider(BaseSpider):
    """Our ad-hoc spider"""
    name = "myspider"
    start_urls = ["http://stackoverflow.com/"]

    question_list_xpath = '//div[@id="content"]//div[contains(@class, "question-summary")]'

    def parse(self, response):
        hxs = HtmlXPathSelector(response)

        for qxs in hxs.select(self.question_list_xpath):
            loader = XPathItemLoader(QuestionItem(), selector=qxs)
            loader.add_xpath('title', './/h3/a/text()')
            loader.add_xpath('summary', './/h3/a/@title')
            loader.add_xpath('tags', './/a[@rel="tag"]/text()')
            loader.add_xpath('user', './/div[@class="started"]/a[2]/text()')
            loader.add_xpath('posted', './/div[@class="started"]/a[1]/span/@title')
            loader.add_xpath('votes', './/div[@class="votes"]/div[1]/text()')
            loader.add_xpath('answers', './/div[contains(@class, "answered")]/div[1]/text()')
            loader.add_xpath('views', './/div[@class="views"]/div[1]/text()')

            yield loader.load_item()


def main():
    """Setups item signal and run the spider"""
    # set up signal to catch items scraped
    from scrapy import signals
    from scrapy.xlib.pydispatch import dispatcher

    def catch_item(sender, item, **kwargs):
        print "Got:", item

    dispatcher.connect(catch_item, signal=signals.item_passed)

    # shut off log
    from scrapy.conf import settings
    settings.overrides['LOG_ENABLED'] = False

    # set up crawler
    from scrapy.crawler import CrawlerProcess

    crawler = CrawlerProcess(settings)
    crawler.install()
    crawler.configure()

    # schedule spider
    crawler.crawl(MySpider())

    # start engine scrapy/twisted
    print "STARTING ENGINE"
    crawler.start()
    print "ENGINE STOPPED"


if __name__ == '__main__':
    main()

# Snippet imported from snippets.scrapy.org (which no longer works)
# author: darkrho
# date  : Aug 25, 2010

Self-contained script to crawl a site [updated: scrapy 13.0dev]

Python