如何使用python修改XML中的元素文本

Question

Would you give me some advice how to modify element text in XML using python? if I want to insert other text in front of text of the first BBB element, which part should i change at the code below?

Please don't use fromstring and other modules(example lxml).

This is sample XML below.

<?xml version="1.0"?>
<data>
    <AAA>
        <CCC>
            <BBB>This</BBB> ----> the first BBB element
        </CCC>
        <CCC>  
            <BBB>is</BBB>
        </CCC>
        <CCC>
            <BBB>test1</BBB>
        </CCC>
    </AAA>

    <AAA>
        <CCC>
            <BBB>This is test</BBB>
        </CCC>
    </AAA>
</data>

---

and it's code what i'm am trying below.

import xml.etree.ElementTree as ET
import re

tree = ET.parse("C:\\test\\python test\\data_text.xml")
root = tree.getroot()                                                

for AAA in root.findall('AAA'):
    for CCC in AAA.findall('CCC'):
        for BBB in CCC.findall('BBB')[0]:
            BBB_text = '11111' + BBB.text
            print(BBB_text)

tree.write('C:\\test\\python test\\output.xml')

As far as i know, for BBB in CCC.findall('BBB')[0]:

[0] means find only the first BBB, but i guess it's wrong.

and this is the result that i want.

<?xml version="1.0"?>
<data>
    <AAA>
        <CCC>
            <BBB>11111This</BBB> ----> the first BBB element
        </CCC>
        <CCC>  
            <BBB>is</BBB>
        </CCC>
        <CCC>
            <BBB>test1</BBB>
        </CCC>
    </AAA>

    <AAA>
        <CCC>
            <BBB>This is test</BBB>
        </CCC>
    </AAA>
</data>

Answer 1

You do not need to iterate all the tags if you just need to update a single tag.

Try:

import xml.etree.ElementTree as ET

tree = ET.parse(filename)
root = tree.getroot()                                                

for AAA in root.findall('AAA'):
    if AAA.find('CCC'):
        BBB = AAA.find('CCC').find('BBB')
        BBB.text = '33333' + BBB.text

tree.write('C:\\test\\python test\\output.xml')

Answer 2

ElementTree supports a limited sub-set of XPath .

You can use

bbb = tree.find("./AAA/CCC/BBB")
if bbb:
    # do something   

to get the very first such node in the tree, or

for bbb in tree.iterfind("./AAA/CCC/BBB"):
    # do something

to iterate over all of them.

Answer 3

Disclaimer: XPath answer from @Tomalak is way more elegant!

---

After some tests, it looks like CCC.findall('BBB')[0] works fine. Since you want the first BBB tag within the document and not within each AAA tag, I would loose the for loops and modify the bit from my comment. I got this:

import xml.etree.ElementTree as ET
import re

tree = ET.parse("data_text.xml")
root = tree.getroot()                                                

AAA = root.find('AAA')
CCC = AAA.find('CCC')
BBB = CCC.find('BBB')
BBB.text = '11111' + BBB.text
print(BBB.text)

tree.write('output.xml')

Seems to do the trick. You may need to check the validity of AAA , BBB and CCC to avoid crashes if the XML does not contain such tags.

Hope this helps.

Answer 4

Well you can do it like this:

for a in tree:
    for c in a:
        for b in c:
            b.text = '11111' + b.text
            break
        break
    break