Append element after another element using lxml

Question

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

CSS only solution: http://www.quirksmode.org/css/clearing.html — fmalina, May 11 '13 at 17:24

score 38 · Accepted Answer · edited May 11 '22 at 12:16

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>

Yeah, I did the same thing after asking the question. :) – Tu Hoang Sep 19 '11 at 21:45 — Tu Hoang, Sep 19 '11 at 21:45

score 16 · Answer 2 · edited May 19 '20 at 05:20

Use addprevious and addnext for prepending and appending siblings.

An lxml.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>

Should probably be ET.HTML in this case – pguardiario Jul 05 '19 at 02:37 — pguardiario, Jul 05 '19 at 02:37

score 2 · Answer 3 · answered Jul 26 '16 at 14:42

2

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)

answered Jul 26 '16 at 14:42

mmj

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51

All that you've done is re-implement `element.appendnext()`. – shrewmouse Oct 22 '17 at 21:31
@Shrewmouse I guess you mean `element.addnext()`. I don't know when it was added to the API but now it is definitively the best solution. – mmj Oct 23 '17 at 23:20

Append element after another element using lxml

3 Answers3

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