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# Define here the models for your spider middleware
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#
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# See documentation in:
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# https://docs.scrapy.org/en/latest/topics/spider-middleware.html
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from scrapy import signals
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# useful for handling different item types with a single interface
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from itemadapter import is_item, ItemAdapter
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class LianjiaSpiderMiddleware:
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# Not all methods need to be defined. If a method is not defined,
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# scrapy acts as if the spider middleware does not modify the
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# passed objects.
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@classmethod
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def from_crawler(cls, crawler):
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# This method is used by Scrapy to create your spiders.
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s = cls()
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crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
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return s
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def process_spider_input(self, response, spider):
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# Called for each response that goes through the spider
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# middleware and into the spider.
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# Should return None or raise an exception.
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return None
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def process_spider_output(self, response, result, spider):
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# Called with the results returned from the Spider, after
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# it has processed the response.
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# Must return an iterable of Request, or item objects.
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for i in result:
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yield i
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def process_spider_exception(self, response, exception, spider):
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# Called when a spider or process_spider_input() method
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# (from other spider middleware) raises an exception.
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# Should return either None or an iterable of Request or item objects.
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pass
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def process_start_requests(self, start_requests, spider):
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# Called with the start requests of the spider, and works
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# similarly to the process_spider_output() method, except
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# that it doesn’t have a response associated.
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# Must return only requests (not items).
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for r in start_requests:
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yield r
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def spider_opened(self, spider):
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spider.logger.info("Spider opened: %s" % spider.name)
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class LianjiaDownloaderMiddleware:
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# Not all methods need to be defined. If a method is not defined,
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# scrapy acts as if the downloader middleware does not modify the
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# passed objects.
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@classmethod
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def from_crawler(cls, crawler):
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# This method is used by Scrapy to create your spiders.
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s = cls()
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crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
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return s
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def process_request(self, request, spider):
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# Called for each request that goes through the downloader
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# middleware.
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# Must either:
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# - return None: continue processing this request
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# - or return a Response object
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# - or return a Request object
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# - or raise IgnoreRequest: process_exception() methods of
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# installed downloader middleware will be called
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return None
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def process_response(self, request, response, spider):
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# Called with the response returned from the downloader.
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# Must either;
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# - return a Response object
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# - return a Request object
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# - or raise IgnoreRequest
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return response
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def process_exception(self, request, exception, spider):
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# Called when a download handler or a process_request()
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# (from other downloader middleware) raises an exception.
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# Must either:
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# - return None: continue processing this exception
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# - return a Response object: stops process_exception() chain
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# - return a Request object: stops process_exception() chain
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pass
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def spider_opened(self, spider):
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spider.logger.info("Spider opened: %s" % spider.name)
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