How to run Scrapy from within a Python script

Question

I'm new to Scrapy and I'm looking for a way to run it from a Python script. I found 2 sources that explain this:

http://tryolabs.com/Blog/2011/09/27/calling-scrapy-python-script/

http://snipplr.com/view/67006/using-scrapy-from-a-script/

I can't figure out where I should put my spider code and how to call it from the main function. Please help. This is the example code:

# This snippet can be used to run scrapy spiders independent of scrapyd or the scrapy command line tool and use it from a script. 
# 
# The multiprocessing library is used in order to work around a bug in Twisted, in which you cannot restart an already running reactor or in this case a scrapy instance.
# 
# [Here](http://groups.google.com/group/scrapy-users/browse_thread/thread/f332fc5b749d401a) is the mailing-list discussion for this snippet. 

#!/usr/bin/python
import os
os.environ.setdefault('SCRAPY_SETTINGS_MODULE', 'project.settings') #Must be at the top before other imports

from scrapy import log, signals, project
from scrapy.xlib.pydispatch import dispatcher
from scrapy.conf import settings
from scrapy.crawler import CrawlerProcess
from multiprocessing import Process, Queue

class CrawlerScript():

    def __init__(self):
        self.crawler = CrawlerProcess(settings)
        if not hasattr(project, 'crawler'):
            self.crawler.install()
        self.crawler.configure()
        self.items = []
        dispatcher.connect(self._item_passed, signals.item_passed)

    def _item_passed(self, item):
        self.items.append(item)

    def _crawl(self, queue, spider_name):
        spider = self.crawler.spiders.create(spider_name)
        if spider:
            self.crawler.queue.append_spider(spider)
        self.crawler.start()
        self.crawler.stop()
        queue.put(self.items)

    def crawl(self, spider):
        queue = Queue()
        p = Process(target=self._crawl, args=(queue, spider,))
        p.start()
        p.join()
        return queue.get(True)

# Usage
if __name__ == "__main__":
    log.start()

    """
    This example runs spider1 and then spider2 three times. 
    """
    items = list()
    crawler = CrawlerScript()
    items.append(crawler.crawl('spider1'))
    for i in range(3):
        items.append(crawler.crawl('spider2'))
    print items

# Snippet imported from snippets.scrapy.org (which no longer works)
# author: joehillen
# date  : Oct 24, 2010

Thank you.

Answer 1

All other answers reference Scrapy v0.x. According to the updated docs, Scrapy 1.0 demands:

import scrapy
from scrapy.crawler import CrawlerProcess

class MySpider(scrapy.Spider):
    # Your spider definition
    ...

process = CrawlerProcess({
    'USER_AGENT': 'Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)'
})

process.crawl(MySpider)
process.start() # the script will block here until the crawling is finished