Scrapy tutorial exceptions

Question

I'm following the Scrapy tutorial documentation at http://media.readthedocs.org/pdf/scrapy/0.14/scrapy.pdf and I've verified that items.py and dmoz_spider.py are typed (not cut & pasted) correctly.

The first "hmmm..." part for me was this instruction:

This is the code for our first Spider; save it in a file named dmoz_spider.py under the dmoz/spiders directory

I'm using the latest version of Ubuntu and there wasn't a dmoz folder created, so I've put this code into ~/tutorial/tutorial/spiders. (Was this my first error?)

So here's my dmoz_spider.py script:

from scrapy.spider import BaseSpider

class DmozSpider(BaseSpider):
   name = "dmoz"
   allowed_domains = ["dmoz.org"]
   start_urls = [
    "http://www.dmoz.org/Computers/Programming/Languages/Python/Books/",
    "http://www.dmoz.org/Computers/Programming/Languages/Python/Resources/"
   ]

def parse(self, response):
   filename = response.url.split("/")[-2]
   open(filename, 'wb').write(response.body)

In my terminal I type

scrapy crawl dmoz

And I get this:

2012-10-08 13:20:22-0700 [scrapy] INFO: Scrapy 0.12.0.2546 started (bot: tutorial)
2012-10-08 13:20:22-0700 [scrapy] DEBUG: Enabled extensions: TelnetConsole, SpiderContext, WebService, CoreStats, MemoryUsage, CloseSpider
2012-10-08 13:20:22-0700 [scrapy] DEBUG: Enabled scheduler middlewares: DuplicatesFilterMiddleware
2012-10-08 13:20:22-0700 [scrapy] DEBUG: Enabled downloader middlewares: HttpAuthMiddleware, DownloadTimeoutMiddleware, UserAgentMiddleware, RetryMiddleware, DefaultHeadersMiddleware, RedirectMiddleware, CookiesMiddleware, HttpCompressionMiddleware, DownloaderStats
2012-10-08 13:20:22-0700 [scrapy] DEBUG: Enabled spider middlewares: HttpErrorMiddleware, OffsiteMiddleware, RefererMiddleware, UrlLengthMiddleware, DepthMiddleware
2012-10-08 13:20:22-0700 [scrapy] DEBUG: Enabled item pipelines: 
2012-10-08 13:20:22-0700 [scrapy] DEBUG: Telnet console listening on 0.0.0.0:6023
2012-10-08 13:20:22-0700 [scrapy] DEBUG: Web service listening on 0.0.0.0:6080
2012-10-08 13:20:22-0700 [dmoz] INFO: Spider opened
2012-10-08 13:20:22-0700 [dmoz] DEBUG: Crawled (200) <GET http://www.dmoz.org/Computers/Programming/Languages/Python/Resources/> (referer: None)
2012-10-08 13:20:22-0700 [dmoz] ERROR: Spider error processing <http://www.dmoz.org/Computers/Programming/Languages/Python/Resources/> (referer: <None>)
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 1178, in mainLoop
    self.runUntilCurrent()
  File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 800, in runUntilCurrent
    call.func(*call.args, **call.kw)
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 362, in callback
    self._startRunCallbacks(result)
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 458, in _startRunCallbacks
    self._runCallbacks()
--- <exception caught here> ---
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 545, in _runCallbacks
    current.result = callback(current.result, *args, **kw)
  File "/usr/lib/python2.7/dist-packages/scrapy/spider.py", line 62, in parse
    raise NotImplementedError
exceptions.NotImplementedError: 

2012-10-08 13:20:22-0700 [dmoz] DEBUG: Crawled (200) <GET http://www.dmoz.org/Computers/Programming/Languages/Python/Books/> (referer: None)
2012-10-08 13:20:22-0700 [dmoz] ERROR: Spider error processing <http://www.dmoz.org/Computers/Programming/Languages/Python/Books/> (referer: <None>)
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 1178, in mainLoop
    self.runUntilCurrent()
  File "/usr/lib/python2.7/dist-packages/twisted/internet/base.py", line 800, in runUntilCurrent
    call.func(*call.args, **call.kw)
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 362, in callback
    self._startRunCallbacks(result)
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 458, in _startRunCallbacks
    self._runCallbacks()
--- <exception caught here> ---
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 545, in _runCallbacks
    current.result = callback(current.result, *args, **kw)
  File "/usr/lib/python2.7/dist-packages/scrapy/spider.py", line 62, in parse
    raise NotImplementedError
exceptions.NotImplementedError: 

2012-10-08 13:20:22-0700 [dmoz] INFO: Closing spider (finished)
2012-10-08 13:20:22-0700 [dmoz] INFO: Spider closed (finished)

In my searching, I saw that someone else had said twisted probably wasn't installed... but wouldn't it be installed if I used the Ubuntu package installer for Scrapy?

Thanks in advance!

Answer 1

The parse method in BaseSpider is getting called instead of your one because you have not correctly overridden the parse method. Your indentation is wrong, so parse is declared as a function outside of the DmozSpider class. Welcome to python :)

It's nothing to do with twisted, I can see that twisted is in the tracebacks, so it's clearly installed.