Python 为什么不是'；XMLFeedSpider未能遍历指定的节点？

我正试图通过解析的RSS提要来获取新的出版物。RSS提要位于

下面是我的蜘蛛：

from scrapy.contrib.spiders import XMLFeedSpider


class PLoSSpider(XMLFeedSpider):
    name = "plos"
    itertag = 'entry'
    allowed_domains = ["plosone.org"]
    start_urls = [
         ('http://www.plosone.org/article/feed/search'
          '?unformattedQuery=*%3A*&sort=Date%2C+newest+first')
    ]

    def parse_node(self, response, node):
        pass

此配置生成以下日志输出（请注意异常）：

以下是输出：

$ scrapy crawl plos
2015-02-06 18:33:01+0100 [scrapy] INFO: Scrapy 0.24.4 started (bot: plos)
2015-02-06 18:33:01+0100 [scrapy] INFO: Optional features available: ssl, http11, boto
2015-02-06 18:33:01+0100 [scrapy] INFO: Overridden settings: {'NEWSPIDER_MODULE': 'plos.spiders', 'SPIDER_MODULES': ['plos.spiders'], 'BOT_NAME': 'plos'}
2015-02-06 18:33:01+0100 [scrapy] INFO: Enabled extensions: LogStats, TelnetConsole, CloseSpider, WebService, CoreStats, SpiderState
2015-02-06 18:33:02+0100 [scrapy] INFO: Enabled downloader middlewares: HttpAuthMiddleware, DownloadTimeoutMiddleware, UserAgentMiddleware, RetryMiddleware, DefaultHeadersMiddleware, MetaRefreshMiddleware, HttpCompressionMiddleware, RedirectMiddleware, CookiesMiddleware, ChunkedTransferMiddleware, DownloaderStats
2015-02-06 18:33:02+0100 [scrapy] INFO: Enabled spider middlewares: HttpErrorMiddleware, OffsiteMiddleware, RefererMiddleware, UrlLengthMiddleware, DepthMiddleware
2015-02-06 18:33:02+0100 [scrapy] INFO: Enabled item pipelines: 
2015-02-06 18:33:02+0100 [plos] INFO: Spider opened
2015-02-06 18:33:02+0100 [plos] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2015-02-06 18:33:02+0100 [scrapy] DEBUG: Telnet console listening on 127.0.0.1:6023
2015-02-06 18:33:02+0100 [scrapy] DEBUG: Web service listening on 127.0.0.1:6080
2015-02-06 18:33:02+0100 [plos] INFO: Closing spider (finished)
2015-02-06 18:33:02+0100 [plos] INFO: Dumping Scrapy stats:
    {'finish_reason': 'finished',
     'finish_time': datetime.datetime(2015, 2, 6, 17, 33, 2, 65414),
     'log_count/DEBUG': 2,
     'log_count/INFO': 7,
     'start_time': datetime.datetime(2015, 2, 6, 17, 33, 2, 60311)}
2015-02-06 18:33:02+0100 [plos] INFO: Spider closed (finished)

还应注意的是，运行

scrapy shell“http://www.plosone.org/article/feed/search?unformattedQuery=*%3A*&sort=Date%2C+newest+first“

后跟

响应。xpath（'//entry'）

生成一个空列表（

[]

）。然而，如果您查看原始XML数据，您可以看到

标记与day一样简单。我完全不知所措，这里…

您需要处理：

另见：

工作示例：

from scrapy.contrib.spiders import XMLFeedSpider


class PLoSSpider(XMLFeedSpider):
    name = "plos"

    namespaces = [('atom', 'http://www.w3.org/2005/Atom')]
    itertag = 'atom:entry'
    iterator = 'xml'

    allowed_domains = ["plosone.org"]
    start_urls = [
         ('http://www.plosone.org/article/feed/search'
          '?unformattedQuery=*%3A*&sort=Date%2C+newest+first')
    ]

    def parse_node(self, response, node):
        print node

---

您能否在此基础上进一步展开，并提供一个可行的示例？我试图修改我的代码（请参见编辑），但我仍然没有看到任何证据表明调用了

parse_node

。@blz当然，更新了答案（注意

iterator='xml'

的重要性-这是我在初始答案中缺少的，抱歉）。感谢更新！您选择名称空间的背后是否有特定的原因？为什么是“atom”及其URL？@blz名称并不重要，但URL是-我从根xml节点获取的。希望这会对你有所帮助，它也会对你有所帮助。@blz谢谢，好吧，这不是我真正的主题，但这篇文章应该澄清一下：）

$ scrapy crawl plos
2015-02-06 18:33:01+0100 [scrapy] INFO: Scrapy 0.24.4 started (bot: plos)
2015-02-06 18:33:01+0100 [scrapy] INFO: Optional features available: ssl, http11, boto
2015-02-06 18:33:01+0100 [scrapy] INFO: Overridden settings: {'NEWSPIDER_MODULE': 'plos.spiders', 'SPIDER_MODULES': ['plos.spiders'], 'BOT_NAME': 'plos'}
2015-02-06 18:33:01+0100 [scrapy] INFO: Enabled extensions: LogStats, TelnetConsole, CloseSpider, WebService, CoreStats, SpiderState
2015-02-06 18:33:02+0100 [scrapy] INFO: Enabled downloader middlewares: HttpAuthMiddleware, DownloadTimeoutMiddleware, UserAgentMiddleware, RetryMiddleware, DefaultHeadersMiddleware, MetaRefreshMiddleware, HttpCompressionMiddleware, RedirectMiddleware, CookiesMiddleware, ChunkedTransferMiddleware, DownloaderStats
2015-02-06 18:33:02+0100 [scrapy] INFO: Enabled spider middlewares: HttpErrorMiddleware, OffsiteMiddleware, RefererMiddleware, UrlLengthMiddleware, DepthMiddleware
2015-02-06 18:33:02+0100 [scrapy] INFO: Enabled item pipelines: 
2015-02-06 18:33:02+0100 [plos] INFO: Spider opened
2015-02-06 18:33:02+0100 [plos] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2015-02-06 18:33:02+0100 [scrapy] DEBUG: Telnet console listening on 127.0.0.1:6023
2015-02-06 18:33:02+0100 [scrapy] DEBUG: Web service listening on 127.0.0.1:6080
2015-02-06 18:33:02+0100 [plos] INFO: Closing spider (finished)
2015-02-06 18:33:02+0100 [plos] INFO: Dumping Scrapy stats:
    {'finish_reason': 'finished',
     'finish_time': datetime.datetime(2015, 2, 6, 17, 33, 2, 65414),
     'log_count/DEBUG': 2,
     'log_count/INFO': 7,
     'start_time': datetime.datetime(2015, 2, 6, 17, 33, 2, 60311)}
2015-02-06 18:33:02+0100 [plos] INFO: Spider closed (finished)

class PLoSSpider(XMLFeedSpider):
    name = "plos"

    namespaces = [('atom', 'http://www.w3.org/2005/Atom')]
    itertag = 'atom:entry'
    iterator = 'xml'  # this is also important

from scrapy.contrib.spiders import XMLFeedSpider


class PLoSSpider(XMLFeedSpider):
    name = "plos"

    namespaces = [('atom', 'http://www.w3.org/2005/Atom')]
    itertag = 'atom:entry'
    iterator = 'xml'

    allowed_domains = ["plosone.org"]
    start_urls = [
         ('http://www.plosone.org/article/feed/search'
          '?unformattedQuery=*%3A*&sort=Date%2C+newest+first')
    ]

    def parse_node(self, response, node):
        print node