python - beautifulsoup:无法在一个循环中提取所有元素

Question

代码:

from bs4 import BeautifulSoup
soup = BeautifulSoup('<div><p>p_string</p><div>div_string</div></div>')
for m in soup.div:
    print "extract(first loop): ", m.extract()
print "current soup.div(frist loop): ", soup.div #it contains another div block
print '___________________________________________________________'

#I have to do another for loop to purge the remaining div block, why?
for m in soup.div:
    print "extract(second loop): ", m.extract()

print "current soup.div(second loop): ", soup.div #removed

结果:

extract(first loop):  <p>p_string</p>
current soup.div(frist loop):  <div><div>div_string</div></div>
___________________________________________________________
extract(second loop):  <div>div_string</div>
current soup.div(second loop):  <div></div>

为什么它没有在第一个 for 循环中提取所有元素(p 和 div)？

Answer 1

这是因为您在循环中调用 extract() ，该循环从树中删除标签 - 在迭代标签的子项时删除它们。与iterating over the list and remove items from it in the loop基本相同。

相反，请使用.find_all() :

for m in soup.div.find_all():
    print m.extract()