2018-08-13 11:37:59 [scrapy.core.scraper] ERROR: Spider error processing <GET https://movie.douban.com/top250> (referer: None)

Traceback (most recent call last):

  File "/usr/local/lib/python3.7/site-packages/scrapy/utils/defer.py", line 102, in iter_errback

    yield next(it)

  File "/usr/local/lib/python3.7/site-packages/scrapy/spidermiddlewares/offsite.py", line 30, in process_spider_output

    for x in result:

  File "/usr/local/lib/python3.7/site-packages/scrapy/spidermiddlewares/referer.py", line 339, in <genexpr>

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

  File "/usr/local/lib/python3.7/site-packages/scrapy/spidermiddlewares/urllength.py", line 37, in <genexpr>

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

  File "/usr/local/lib/python3.7/site-packages/scrapy/spidermiddlewares/depth.py", line 58, in <genexpr>

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

  File "/usr/local/douban/douban/spiders/douban_spider.py", line 36, in parse

    next_link = response.xpath("//span[@class='next']/link/@href").extarct()

AttributeError: 'SelectorList' object has no attribute 'extarct'

大壮老师，我根据你的教程后亲测了一下，发现在抓取后页URL时，不能正确获取到，拿到的数据只有前25条。
请大壮老师赐教一番。