标签：lib 运行 call des self contains @class tree .com
1.环境及版本
python3.7.1+scrapy1.5.1
2.问题及错误代码详情
优先贴上问题代码，如下：
import scrapy from scrapy.linkextractors import LinkExtractor class MatExamplesSpider(scrapy.Spider): name = ‘mat_examples‘ # allowed_domains = [‘matplotlib.org‘] start_urls = [‘https://matplotlib.org/gallery/index.html‘] def parse(self, response): le = LinkExtractor(restrict_xpaths=‘//a[contains(@class, "reference internal")]/@href‘) links = le.extract_links(response) print(response.url) print(type(links)) print(links)
运行代码后报错如下：
Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/twisted/internet/defer.py", line 654, in _runCallbacks
current.result = callback(current.result, *args, **kw)
File "/Users/eric.luo/Desktop/Python/matplotlib_examples/matplotlib_examples/spiders/mat_examples.py", line 14, in parse
links = le.extract_links(response)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/scrapy/linkextractors/lxmlhtml.py", line 128, in extract_links
links = self._extract_links(doc, response.url, response.encoding, base_url)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/scrapy/linkextractors/__init__.py", line 109, in _extract_links
return self.link_extractor._extract_links(*args, **kwargs)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/scrapy/linkextractors/lxmlhtml.py", line 58, in _extract_links
for el, attr, attr_val in self._iter_links(selector.root):
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/scrapy/linkextractors/lxmlhtml.py", line 46, in _iter_links
for el in document.iter(etree.Element):
AttributeError: ‘str‘ object has no attribute ‘iter‘
出现错误后自检代码并未发现问题，上网查找也未发现相关的问题；于是将代码改成（restrict_css）去抓取数据，发现是能正常获取到数据的，于是改回xpath；但这次先不使用linkextractor，采用scrapy自带的response.xpath()方法去获取对应链接所在标签的href属性值；发现这样是可以获取到正常的数据的：
即将：
le = LinkExtractor(restrict_xpaths=‘//a[contains(@class, "reference internal")]/@href‘) links = le.extract_links(response)
改成：
links = respon.xpath(‘//a[contains(@class, "reference internal")]/@href‘).extract()
然后又发现报错是： ‘str‘ object has no attribute ‘iter‘
而正常返回的links数据类型应该是list才对，不应该是str，所以猜测可能是由于规则写错了导致获取的数据不是list而变成了一个不知道的str；这样针对性的去修改restrict_xpaths中的规则，最后发现去掉／@href后能够获取我所需要的正常的数据；
即将：
le = LinkExtractor(restrict_xpaths=‘//a[contains(@class, "reference internal")]/@href‘)
改成：
le = LinkExtractor(restrict_xpaths=‘//a[contains(@class, "reference internal")]‘)
重新运行代码，发现成功获取数据，输出结果如下截图所示：
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Python之scrapy linkextractors使用错误
标签：lib 运行 call des self contains @class tree .com
原文地址：https://www.cnblogs.com/dluo/p/10315305.html
