How to modify element text in XML using python

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

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 2

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

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.