import scrapy

 import sys

 class Jizhi(scrapy.Spider):

     name = 'jizhi'

     arg = ' '.join(sys.argv[3:])

     base_urls = "https://www.baidu.com"

     start_urls = [

         'https://www.baidu.com/s?{}'.format(arg)

     ]

     counter = 0

     def parse(self, response):

         result_lst = response.css("h3.t a::text")

         for result in result_lst:

             yield {

                 'title':result.extract()

             }

         Jizhi.counter +=1

         # next_page:css('a.n')

         if Jizhi.counter == 5: return        

         next_page = response.css('a.n::attr(href)')

         if len(next_page) == 2:

             next_page_url = next_page[1].extract()

         else:

             next_page_url = next_page.extract_first()

         yield scrapy.Request(self.base_urls + next_page_url, callback=self.parse)

2018-07-26 09:37:28 [scrapy.utils.log] INFO: Scrapy 1.5.0 started (bot: jizhi)

2018-07-26 09:37:28 [scrapy.utils.log] INFO: Versions: lxml 4.2.1.0, libxml2 2.9.8, cssselect 1.0.3, parsel 1.4.0, w3lib 1.19.0, Twisted 17.5.0, Python 3.6.5 |Anaconda, Inc.| (default, Mar 29 2018, 13:32:41) [MSC v.1900 64 bit (AMD64)], pyOpenSSL 18.0.0 (OpenSSL 1.0.2k  26 Jan 2017), cryptography 2.2.2, Platform Windows-10-10.0.17134-SP0

2018-07-26 09:37:28 [scrapy.crawler] INFO: Overridden settings: {'BOT_NAME': 'jizhi', 'NEWSPIDER_MODULE': 'jizhi.spiders', 'SPIDER_MODULES': ['jizhi.spiders']}

2018-07-26 09:37:29 [scrapy.middleware] INFO: Enabled extensions:

['scrapy.extensions.corestats.CoreStats',

 'scrapy.extensions.telnet.TelnetConsole',

 'scrapy.extensions.logstats.LogStats']

2018-07-26 09:37:29 [scrapy.middleware] INFO: Enabled downloader middlewares:

['scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware',

 'scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware',

 'scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware',

 'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware',

 'scrapy.downloadermiddlewares.retry.RetryMiddleware',

 'scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware',

 'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware',

 'scrapy.downloadermiddlewares.redirect.RedirectMiddleware',

 'scrapy.downloadermiddlewares.cookies.CookiesMiddleware',

 'scrapy.downloadermiddlewares.httpproxy.HttpProxyMiddleware',

 'scrapy.downloadermiddlewares.stats.DownloaderStats']

2018-07-26 09:37:29 [scrapy.middleware] INFO: Enabled spider middlewares:

['scrapy.spidermiddlewares.httperror.HttpErrorMiddleware',

 'scrapy.spidermiddlewares.offsite.OffsiteMiddleware',

 'scrapy.spidermiddlewares.referer.RefererMiddleware',

 'scrapy.spidermiddlewares.urllength.UrlLengthMiddleware',

 'scrapy.spidermiddlewares.depth.DepthMiddleware']

2018-07-26 09:37:29 [scrapy.middleware] INFO: Enabled item pipelines:

[]

2018-07-26 09:37:29 [scrapy.core.engine] INFO: Spider opened

2018-07-26 09:37:29 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)

2018-07-26 09:37:29 [scrapy.extensions.telnet] DEBUG: Telnet console listening on 127.0.0.1:6023

2018-07-26 09:37:29 [scrapy.core.engine] DEBUG: Crawled (200) <GET https://www.baidu.com/s?wd=jizhi> (referer: None)

2018-07-26 09:37:29 [scrapy.core.scraper] ERROR: Spider error processing <GET https://www.baidu.com/s?wd=jizhi> (referer: None)

Traceback (most recent call last):

  File "C:\Users\asus\Anaconda3\lib\site-packages\scrapy\utils\defer.py", line 102, in iter_errback

    yield next(it)

  File "C:\Users\asus\Anaconda3\lib\site-packages\scrapy\spidermiddlewares\offsite.py", line 30, in process_spider_output

    for x in result:

  File "C:\Users\asus\Anaconda3\lib\site-packages\scrapy\spidermiddlewares\referer.py", line 339, in <genexpr>

    return (_set_referer(r) for r in result or ())

  File "C:\Users\asus\Anaconda3\lib\site-packages\scrapy\spidermiddlewares\urllength.py", line 37, in <genexpr>

    return (r for r in result or () if _filter(r))

  File "C:\Users\asus\Anaconda3\lib\site-packages\scrapy\spidermiddlewares\depth.py", line 58, in <genexpr>

    return (r for r in result or () if _filter(r))

  File "C:\Users\asus\Documents\GitHub\spider\jizhi\jizhi\spiders\jizhi.py", line 40, in parse

    yield scrapy.Request(self.base_urls + next_page_url, callback=self.parse)

TypeError: must be str, not NoneType

2018-07-26 09:37:29 [scrapy.core.engine] INFO: Closing spider (finished)

2018-07-26 09:37:29 [scrapy.statscollectors] INFO: Dumping Scrapy stats:

{'downloader/request_bytes': 222,

 'downloader/request_count': 1,

 'downloader/request_method_count/GET': 1,

 'downloader/response_bytes': 872,

 'downloader/response_count': 1,

 'downloader/response_status_count/200': 1,

 'finish_reason': 'finished',

 'finish_time': datetime.datetime(2018, 7, 26, 1, 37, 29, 585191),

 '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/TypeError': 1,

 'start_time': datetime.datetime(2018, 7, 26, 1, 37, 29, 324887)}

2018-07-26 09:37:29 [scrapy.core.engine] INFO: Spider closed (finished)