我在用scrappy shell做一些样本测试
在我输入'response.xpath（'//h1/text（）'）.get（）'之后
它给了我AttributeError：“Selector”对象没有属性“_default_type”
有人能帮忙吗？
非常感谢
下面是我在终端输入的内容
scrapy shell
fetch("https://www.worldometers.info/world-population/population-by-country/")
r = scrapy.Request(url="https://www.worldometers.info/world-population/population-by-country/")
fetch(r)
response.xpath('//h1/text()').get()
在最后一行之前一切都很顺利。在我输入'response.xpath（'//h1/text（）'）.get（）'后，它抛出一个错误：

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-5-7a322073163e> in <module>
----> 1 response.xpath('//h1/text()').get()

~/anaconda3/envs/virtual_work/lib/python3.7/site-packages/scrapy/http/response/text.py in xpath(self, query, **kwargs)
    117 
    118     def xpath(self, query, **kwargs):
--> 119         return self.selector.xpath(query, **kwargs)
    120 
    121     def css(self, query):

~/anaconda3/envs/virtual_work/lib/python3.7/site-packages/scrapy/http/response/text.py in selector(self)
    113         from scrapy.selector import Selector
    114         if self._cached_selector is None:
--> 115             self._cached_selector = Selector(self)
    116         return self._cached_selector
    117 

~/anaconda3/envs/virtual_work/lib/python3.7/site-packages/scrapy/selector/unified.py in __init__(self, response, text, type, root, _root, **kwargs)
     84                             % self.__class__.__name__)
     85 
---> 86         st = _st(response, type or self._default_type)
     87 
     88         if _root is not None:
AttributeError: 'Selector' object has no attribute '_default_type'