使用scrapy来刮擦雅虎组的问题

Question

我是网络抓取的新手,刚刚开始尝试用Python编写的抓取框架Scrapy.我的目标是刮掉旧的雅虎集团,因为他们没有提供API或任何其他方法来检索邮件存档.雅虎集团的设置使您必须先登录才能查看档案.

我认为,我需要完成的步骤是:

1. 登录雅虎
2. 访问第一条消息的URL并抓取它
3. 对下一条消息等重复步骤2

我开始粗略地用scrapy蜘蛛完成上面的工作,这就是我到目前为止所拥有的.我想要观察的是登录工作,我能够检索第一条消息.一旦我开始工作,我将完成其余的工作:

class Sg101Spider(BaseSpider):
    name = "sg101"
    msg_id = 1              # current message to retrieve
    max_msg_id = 21399      # last message to retrieve

    def start_requests(self):
        return [FormRequest(LOGIN_URL,
            formdata={'login': LOGIN, 'passwd': PASSWORD},
            callback=self.logged_in)]

    def logged_in(self, response):
        if response.url == 'http://my.yahoo.com':
            self.log("Successfully logged in. Now requesting 1st message.")
            return Request(MSG_URL % self.msg_id, callback=self.parse_msg,
                    errback=self.error)
        else:
            self.log("Login failed.")

    def parse_msg(self, response):
        self.log("Got message!")
        print response.body

    def error(self, failure):
        self.log("I haz an error")

当我运行蜘蛛时,我看到它登录并发出第一条消息的请求.但是,我在scrapy的调试输出中看到的只有3个重定向,最终到达我首先要求的URL.但scrapy不会调用我的parse_msg()回调,并且爬行停止.这是scrapy输出的片段:

2011-02-03 19:50:10-0600 [sg101] INFO: Spider opened
2011-02-03 19:50:10-0600 [sg101] DEBUG: Redirecting (302) to <GET https://login.yahoo.com/config/verify?.done=http%3a//my.yahoo.com> from <POST https://login.yahoo.com/config/login>
2011-02-03 19:50:10-0600 [sg101] DEBUG: Redirecting (meta refresh) to <GET http://my.yahoo.com> from <GET https://login.yahoo.com/config/verify?.done=http%3a//my.yahoo.com>
2011-02-03 19:50:12-0600 [sg101] DEBUG: Crawled (200) <GET http://my.yahoo.com> (referer: None)
2011-02-03 19:50:12-0600 [sg101] DEBUG: Successfully logged in. Now requesting 1st message.
2011-02-03 19:50:12-0600 [sg101] DEBUG: Redirecting (302) to <GET http://launch.groups.yahoo.com/group/MyYahooGroup/auth?done=http%3A%2F%2Flaunch.groups.yahoo.com%2Fgroup%2FMyYahooGroup%2Fmessage%2F1> from <GET http://launch.groups.yahoo.com/group/MyYahooGroup/message/1>
2011-02-03 19:50:12-0600 [sg101] DEBUG: Redirecting (302) to <GET http://launch.groups.yahoo.com/group/MyYahooGroup/auth?check=G&done=http%3A%2F%2Flaunch%2Egroups%2Eyahoo%2Ecom%2Fgroup%2FMyYahooGroup%2Fmessage%2F1> from <GET http://launch.groups.yahoo.com/group/MyYahooGroup/auth?done=http%3A%2F%2Flaunch.groups.yahoo.com%2Fgroup%2FMyYahooGroup%2Fmessage%2F1>
2011-02-03 19:50:13-0600 [sg101] DEBUG: Redirecting (302) to <GET http://launch.groups.yahoo.com/group/MyYahooGroup/message/1> from <GET http://launch.groups.yahoo.com/group/MyYahooGroup/auth?check=G&done=http%3A%2F%2Flaunch%2Egroups%2Eyahoo%2Ecom%2Fgroup%2FMyYahooGroup%2Fmessage%2F1>
2011-02-03 19:50:13-0600 [sg101] INFO: Closing spider (finished)
2011-02-03 19:50:13-0600 [sg101] INFO: Spider closed (finished)

我无法理解这一点.看起来雅虎正在重定向蜘蛛(也许是为了验证身份？)但它似乎首先回到了我想要访问的URL.但scrapy不会调用我的回调,我没有机会刮取数据或继续爬行.

有没有人对正在发生的事情有什么想法和/或如何进一步调试？谢谢!

Answer 1

我认为雅虎正在重定向进行授权检查,最终将我重定向回我真正想要的页面.然而,Scrapy已经看到了这个请求,因为它不想进入循环而停止.在我的例子中,解决方案是添加dont_filter=True到Request构造函数.这将指示Scrapy不过滤掉重复的请求.这在我的情况下很好,因为我事先知道我想要抓取哪些网址.

def logged_in(self, response):
    if response.url == 'http://my.yahoo.com':
        self.log("Successfully logged in. Now requesting message page.",
                level=log.INFO)
        return Request(MSG_URL % self.msg_id, callback=self.parse_msg,
                errback=self.error, dont_filter=True)
    else:
        self.log("Login failed.", level=log.CRITICAL)