find() after replaceWith() doesn't work (using BeautifulSoup)

问题

Please consider the following python session:

>>> from BeautifulSoup import BeautifulSoup
>>> s = BeautifulSoup("<p>This <i>is</i> a <i>test</i>.</p>"); myi = s.find("i")
>>> myi.replaceWith(BeautifulSoup("was"))
>>> s.find("i")
>>> s = BeautifulSoup("<p>This <i>is</i> a <i>test</i>.</p>"); myi = s.find("i")
>>> myi.replaceWith("was")
>>> s.find("i")
<i>test</i>

Please note the missing output of s.find("i") after line 4!

What's the reason for this? Is there a workaround?

EDIT: Actually, the example doesn't demonstrate the usecase, which is:

myi.replaceWith(BeautifulSoup("wa<b>s</b>"))

Whenever the inserted part contains itself nontrivial html code, I don't see how you could replace this syntax with something else. Just having

myi.replaceWith("wa<b>s</b>")

will replace the html special chars by entities.

回答1:

Simpler answer : after your call to replaceWith, regenerate and clean s by calling s = BeautifulSoup(s.renderContents()). Then you can find again.

回答2:

The problem seems to be that a BeautifulSoup object is considered an entire document. find iterates through the document asking each element for the next element after it. But when it gets to your BeautifulSoup("was"), that object thinks it is the whole document, so it says there is nothing after it. This aborts the search too early.

I don't think BeautifulSoup is designed to have BeautifulSoup objects inside other BeautifulSoup objects. The workaround is don't do that. Why do you feel you need to use the first form instead of the second one, which already works? If you want to replace an element with some bit of HTML, use a Tag for your replacement, not a BeautifulSoup object.

回答3:

I think, I found a workaround, which solves the issue for me. I repeat the whole code again as a Python script to give a complete example:

from BeautifulSoup import BeautifulSoup
s = BeautifulSoup("<p>This <i>is</i> a <i>test</i>.</p>")
myi = s.find("i")
s2 = BeautifulSoup("wa<b>s</b>")
myi_id = myi.parent.contents.index(myi)
for c in reversed(s2.contents):
    myi.parent.insert(myi_id + 1, c)
myi.extract()

Please note, that this won't work without reversed(). If you skip it, you don't only change the order of the elements. If you really want the order to be changed, you will have to write the following:

for c in list(s2.contents):
    myi.parent.insert(myi_id + 1, c)

Can somebody please explain, why skipping list() will omit <b>s</b>? (Please answer in a comment, because this is not the main question here.)

来源：https://stackoverflow.com/questions/15455148/find-after-replacewith-doesnt-work-using-beautifulsoup

标签

python

find

beautifulsoup