python lxml append element after another element

2019-01-24 03:09发布

站内文章 / Python
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问题:

I have the following HTML markup

<div id="contents">
    <div id="content_nav">
        something goes here
    </div>
    <p>
        some contents
    </p>   
</div>

To fix some CSS issue, I want to append a div tag <div style="clear:both"></div> after the content_nav div like this

<div id="contents">
    <div id="content_nav">
        something goes here
    </div>

    <div style="clear:both"></div>

    <p>
        some contents
    </p>   
</div>

I am doing it this way:

import lxml.etree

tree = lxml.etree.fromString(inputString, parser=lxml.etree.HTMLParser())

contentnav = tree.find(".//div[@id='content_nav']")
contentnav.append(lxml.etree.XML("<div style='clear: both'></div>"))

But that doesn't append the new div right after content_nav div but inside.

<div id="content_nav">
    something goes here
    <div style="clear:both"></div>
</div>

Is there any way to add a div in the middle of content_nav div and some p like that inside contents?

Thanks

回答1:

Instead of appending to contentnav, go up to the parent (contentdiv) and insert the new div at a particular index. To find that index, use contentdiv.index(contentnav), which gives the index of contentnav within contentdiv. Adding one to that gives the desired index.

import lxml.etree as ET

content='''\
<div id="contents">
    <div id="content_nav">
        something goes here
    </div>
    <p>
        some contents
    </p>   
</div>
'''
tree = ET.fromstring(content, parser=ET.HTMLParser())
contentnav = tree.find(".//div[@id='content_nav']")
contentdiv = contentnav.getparent()
contentdiv.insert(contentdiv.index(contentnav)+1,
                  ET.XML("<div style='clear: both'></div>"))
print(ET.tostring(tree))

yields

<html><body><div id="contents">
    <div id="content_nav">
        something goes here
    </div>
    <div style="clear: both"/><p>
        some contents
    </p>   
</div></body></html>


回答2:

Use addprevious and addnext for prepending and appending siblings.

An etree element has two methods: addprevious and addnext for doing exactly what you want.

import lxml.etree as ET

content='''\
<div id="contents">
    <div id="content_nav">
        something goes here
    </div>
    <p>
        some contents
    </p>   
</div>
'''
tree = ET.fromstring(content, parser=ET.HTMLParser())
contentnav = tree.find(".//div[@id='content_nav']")
contentnav.addnext(ET.XML("<div style='clear: both'></div>"))
print(ET.tostring(tree))

Output:

<html><body><div id="contents">
    <div id="content_nav">
        something goes here
    </div><div style="clear: both"/>
    <p>
        some contents
    </p>   
</div>
</body></html>


回答3:

I believe that a generic function addressing the question "insert an element after another element" might be useful, even if it's just a reformulation of the accepted answer:

def insert_after(element, new_element):
    parent = element.getparent()
    parent.insert(parent.index(element)+1, new_element)

which allows to insert a new_element after an existing element with just

insert_after(element, new_element)


标签： python html append lxml
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