python - 为什么我的第二个请求没有在我的 scrapy 蜘蛛的解析方法中被调用

Question

我试图发出两个请求，但只有第一个被调用。更具体地说，似乎只有第一个回调 parse() 被调用。我指定 parse2 作为第二个回调，但根据我的输出，它似乎根本没有被调用。

import scrapy

class ExampleSpider(scrapy.Spider):
    name = "example"
    allowed_domains = ["https://www.reddit.com"]
    start_urls = (
        'https://www.reddit.com/',
    )

    def start_requests(self):
        return [scrapy.Request(
            self.start_urls[0],
            method='GET'
        )]

    def parse(self, response):
        return [scrapy.Request(self.start_urls[0], callback=self.parse2)]

    def parse2(self, response):
        print(response.body[:40])

输出:

2016-01-15 01:19:19 [scrapy] INFO: Scrapy 1.0.4 started (bot: example)
2016-01-15 01:19:19 [scrapy] INFO: Optional features available: ssl, http11
2016-01-15 01:19:19 [scrapy] INFO: Overridden settings: {'NEWSPIDER_MODULE': 'example.spiders', 'SPIDER_MODULES': ['example.spiders'], 'BOT_NAME': 'example'}
2016-01-15 01:19:19 [scrapy] INFO: Enabled extensions: CloseSpider, TelnetConsole, LogStats, CoreStats, SpiderState
2016-01-15 01:19:19 [scrapy] INFO: Enabled downloader middlewares: DownloadTimeoutMiddleware, UserAgentMiddleware, RetryMiddleware, HttpAuthMiddleware, DefaultHeadersMiddleware, MetaRefreshMiddleware, HttpCompressionMiddleware, RedirectMiddleware, CookiesMiddleware, ChunkedTransferMiddleware, DownloaderStats
2016-01-15 01:19:19 [scrapy] INFO: Enabled spider middlewares: HttpErrorMiddleware, OffsiteMiddleware, RefererMiddleware, UrlLengthMiddleware, DepthMiddleware
2016-01-15 01:19:19 [scrapy] INFO: Enabled item pipelines:
2016-01-15 01:19:19 [scrapy] INFO: Spider opened
2016-01-15 01:19:19 [scrapy] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2016-01-15 01:19:19 [scrapy] DEBUG: Telnet console listening on 127.0.0.1:6023
2016-01-15 01:19:19 [scrapy] DEBUG: Crawled (200) <GET https://www.reddit.com/> (referer: None)
2016-01-15 01:19:19 [scrapy] DEBUG: Filtered offsite request to 'www.reddit.com': <GET https://www.reddit.com/>
2016-01-15 01:19:19 [scrapy] INFO: Closing spider (finished)
2016-01-15 01:19:19 [scrapy] INFO: Dumping Scrapy stats:
{'downloader/request_bytes': 212,
 'downloader/request_count': 1,
 'downloader/request_method_count/GET': 1,
 'downloader/response_bytes': 22307,
 'downloader/response_count': 1,
 'downloader/response_status_count/200': 1,
 'finish_reason': 'finished',
 'finish_time': datetime.datetime(2016, 1, 15, 6, 19, 19, 898275),
 'log_count/DEBUG': 3,
 'log_count/INFO': 7,
 'offsite/domains': 1,
 'offsite/filtered': 1,
 'request_depth_max': 1,
 'response_received_count': 1,
 'scheduler/dequeued': 1,
 'scheduler/dequeued/memory': 1,
 'scheduler/enqueued': 1,
 'scheduler/enqueued/memory': 1,
 'start_time': datetime.datetime(2016, 1, 15, 6, 19, 19, 692480)}

Answer 1

这是因为它被作为重复请求过滤掉。要更改行为，请传递 dont_filter=True当您发出请求时:

def parse(self, response):
    return scrapy.Request(self.start_urls[0], 
                          callback=self.parse2, 
                          dont_filter=True)