Question

我在Windows 7上，并且我按照本教程进行操作：

https://realpython.com/blog/python/web-scraping-with-scrapy-and-mongodb/

这是我的代码：

from scrapy import Spider
from scrapy.selector import Selector
from stack.items import StackItem


class StackSpider(Spider):
    name = "stack"
    allowed_domains = ["stackoverflow.com"]
    start_urls = [
        "http://stackoverflow.com/questions?pagesize=50&sort=newest",
    ]

    def parse(self, response):
        questions = Selector(response).xpath('//div[@class="summary"]/h3')

        for question in questions:
            item = StackItem()
            item['title'] = question.xpath(
                'a[@class="question-hyperlink"]/text()').extract()[0]
            item['url'] = question.xpath(
                'a[@class="question-hyperlink"]/@href').extract()[0]
            yield item

这就是CMD的回归

2015-10-21 20:28:19 [scrapy] INFO: Scrapy 1.0.3 started (bot: stack)
2015-10-21 20:28:19 [scrapy] INFO: Optional features available: ssl, http11
2015-10-21 20:28:19 [scrapy] INFO: Overridden settings: {'NEWSPIDER_MODULE': 'stack.spiders', 'SPIDER_MODULES': ['stack.spiders'], 'BOT_NAME': 'stack'}
2015-10-21 20:28:19 [scrapy] INFO: Enabled extensions: CloseSpider, TelnetConsole, LogStats, CoreStats, SpiderState
2015-10-21 20:28:19 [scrapy] INFO: Enabled downloader middlewares: HttpAuthMiddleware, DownloadTimeoutMiddleware, UserAgentMiddleware, RetryMiddleware, DefaultHeadersMiddleware, MetaRefreshMiddleware, HttpCompressionMiddleware, RedirectMiddleware, CookiesMiddleware, ChunkedTransferMiddleware, DownloaderStats
2015-10-21 20:28:19 [scrapy] INFO: Enabled spider middlewares: HttpErrorMiddleware, OffsiteMiddleware, RefererMiddleware, UrlLengthMiddleware, DepthMiddleware
2015-10-21 20:28:19 [scrapy] INFO: Enabled item pipelines:
2015-10-21 20:28:19 [scrapy] INFO: Spider opened
2015-10-21 20:28:19 [scrapy] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2015-10-21 20:28:19 [scrapy] DEBUG: Telnet console listening on 127.0.0.1:6023
2015-10-21 20:28:19 [scrapy] DEBUG: Crawled (200) <GET http://stackoverflow.com/questions?pagesize=50&sort=newest> (referer: None)
2015-10-21 20:28:20 [scrapy] ERROR: Spider error processing <GET http://stackoverflow.com/questions?pagesize=50&sort=newest> (referer: None)
Traceback (most recent call last):
  File "C:\Python27\lib\site-packages\scrapy\utils\defer.py", line 102, in iter_errback
    yield next(it)
  File "C:\Python27\lib\site-packages\scrapy\spidermiddlewares\offsite.py", line 28, in process_spider_output
    for x in result:
  File "C:\Python27\lib\site-packages\scrapy\spidermiddlewares\referer.py", line 22, in <genexpr>
    return (_set_referer(r) for r in result or ())
  File "C:\Python27\lib\site-packages\scrapy\spidermiddlewares\urllength.py", line 37, in <genexpr>
    return (r for r in result or () if _filter(r))
  File "C:\Python27\lib\site-packages\scrapy\spidermiddlewares\depth.py", line 54, in <genexpr>
    return (r for r in result or () if _filter(r))
  File "C:\Users\unska\Desktop\python\blogspot\stack\stack\spiders\stack_spider.py", line 21, in parse
    'a[@class="question-hyperlink"]/text()').extract()[0]
  File "C:\Python27\lib\site-packages\scrapy\item.py", line 63, in __setitem__
    (self.__class__.__name__, key))
KeyError: 'StackItem does not support field: title'
2015-10-21 20:28:20 [scrapy] INFO: Closing spider (finished)
2015-10-21 20:28:20 [scrapy] INFO: Dumping Scrapy stats:
{'downloader/request_bytes': 248,
 'downloader/request_count': 1,
 'downloader/request_method_count/GET': 1,
 'downloader/response_bytes': 29059,
 'downloader/response_count': 1,
 'downloader/response_status_count/200': 1,
 'finish_reason': 'finished',
 'finish_time': datetime.datetime(2015, 10, 21, 17, 28, 20, 95000),
 'log_count/DEBUG': 2,
 'log_count/ERROR': 1,
 'log_count/INFO': 7,
 'response_received_count': 1,
 'scheduler/dequeued': 1,
 'scheduler/dequeued/memory': 1,
 'scheduler/enqueued': 1,
 'scheduler/enqueued/memory': 1,
 'spider_exceptions/KeyError': 1,
 'start_time': datetime.datetime(2015, 10, 21, 17, 28, 19, 585000)}
2015-10-21 20:28:20 [scrapy] INFO: Spider closed (finished)

这里似乎有什么问题？

PS。

获取＆＃34;您的帖子似乎主要是代码＆＃34;，所以我必须在这里随意写一些内容......

Answer 1

您收到此错误：

KeyError: 'StackItem does not support field: title'

您正在尝试分配一个项目，一个不存在的字段：

 item['title'] = question.xpath(
            'a[@class="question-hyperlink"]/text()').extract()[0]

来自StackItem的{{1}}不包含字段stack.items。标题不会显示为title类中的属性。只需在StackItem中添加title。

Scrapy返回＆＃34;抓取0页＆＃34;

1 个答案: