Python 提示 AttributeError: ‘NoneType‘ object has no attribute ‘append‘
1、情景复现
今天编写了一个爬虫脚本，最后把爬取的信息整合成列表的时候，就提示 AttributeError: ‘NoneType’ object has no attribute ‘append’
代码如下：
import requests
from lxml import etree
html = requests.get('https://www.cczu.edu.cn/')
html.encoding = "utf-8"
tree = etree.HTML(html.text)
a = tree.xpath("//ul[@class='clearfix']/li")
total = []
for i in a:
title = ''.join(i.xpath('.//h2//text()'))
time = ''.join(i.xpath('.//h3//text()'))
link = ''.join(i.xpath('./h2/a/@href'))
total = total.append({'title': title, 'url': link, 'date': time})
print(total)
2、原因
打断点调试一下，发现执行一次后发现 total 的类型变为了 NoneType，原来 append 会修改 total 本身，并且返回 None，不能把返回值再赋值给 total。
3、解决
把 total = total.append({'title': title, 'url': link, 'date': time}) 改为 total.append({'title': title, 'url': link, 'date': time}) 就解决问题了
正确代码如下：
import requests
from lxml import etree
html = requests.get('https://www.cczu.edu.cn/')
html.encoding = "utf-8"
tree = etree.HTML(html.text)
a = tree.xpath("//ul[@class='clearfix']/li")
total = []
for i in a:
title = ''.join(i.xpath('.//h2//text()'))
time = ''.join(i.xpath('.//h3//text()'))
link = ''.join(i.xpath('./h2/a/@href'))
total.append({'title': title, 'url': link, 'date': time})
print(total)
