How to append data to existing xml file using Python

Question

I have to add a new line like ./dir/pqr in the <filename sections to the following existing xml file. The 'url' is a link

<dbchangelog
    xmlns="http://url/xml/ns/dbchangelog"
    xmlns:xsi="http://url/2001/XMLSchema-instance"
    xsi:schemaLocation="http://url/xml/ns/dbchangelog http://url/xml/ns/dbchangelog-4.1.xsd">
    <changeSet author="name" id="v3.0.0">
        <tagDatabase tag="release/v3.0.0" />
    </changeSet>
    <dependencyManagement>
        <dependencies>
            <path>
                <filename>./dir/commons</filename>
            </path>
            <path>
                <filename>./dir/abc</filename>
            </path>
            <path>
                <filename>./dir/xyz</filename>
            </path>
        </dependencies>
    </dependencyManagement>
</dbchangelog>

Tried following piece of code, it prints the appended value but doesn't actually append to the file.

import xml.etree.ElementTree as ET 
tree = ET.parse('pqr.xml')
root = tree.getroot() 
b = ET.SubElement(root, 'filename')
b.text = './dml/release/v3.0.0/abc_changelog.xml' 
print ET.tostring(root)

Does this answer your question? python elementtree xml append — Sebastian_Ulrich
– Sebastian_Ulrich, Commented Feb 19, 2024 at 9:46
No, it doesn't. probably because the xml structure is different. I have found multiple answers but none woks for the said xml file — Shivani
– Shivani, Commented Feb 19, 2024 at 11:23

Hermann12 · Accepted Answer · 2024-02-19 14:36:50Z

0

You have to register the Namespace and insert than the attribute instead text:

import xml.etree.ElementTree as ET

tree = ET.parse('pqr.xml')
root = tree.getroot()

# Register the Namespace
ns = {'': 'http://url/xml/ns/dblogs', 'xsi': 'http://url/2001/XMLSchema-instance', 'pro': 'http://url/xml/ns/dblogs/ns/pro'}
for key, value in ns.items():
    ET.register_namespace(key, value)

# Set attribute value instead of text
b = ET.SubElement(root, 'include')
b.attrib['file'] = './dml/release/v3.0.0/abc_changelog.xml'

ET.indent(root, space='  ')
ET.dump(root)

# Write the result to a new file:
tree = ET.ElementTree(root)
ET.indent(tree, space='  ')
tree.write("out_new.xml", xml_declaration=True, encoding='UTF-8')

Output:

<dblogs xmlns="http://url/xml/ns/dblogs" xmlns:xsi="http://url/2001/XMLSchema-instance" xsi:schemaLocation="http://url/xml/ns/dblogs">
  <changeSet author="user_id" id="v3.0.0">
    <tagDatabase tag="release/v3.0.0" />
  </changeSet>
  <include file="./file_one.xml" />
  <include file="./file_two.xml" />
  <include file="./dml/release/v3.0.0/abc_changelog.xml" />
</dblogs>

edited Feb 19, 2024 at 14:36

answered Feb 19, 2024 at 12:40

Hermann12

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2 Comments

Shivani Over a year ago

But when i open the pqr.xml, I don't see any new line added, though it's displayed in the output

Shivani Over a year ago

How do I read the xmlns value while parsing the xml file ? The output must be url/xml/ns/dblogs

Sebastian_Ulrich · Accepted Answer · 2024-02-19 12:23:46Z

0

You are missing a closing " in the following line:

xsi:schemaLocation="http://url/xml/ns/dblogs >

When adding this your code works for me with following output:

b'<ns0:dblogs xmlns:ns0="http://url/xml/ns/dblogs" xmlns:ns1="http://url/2001/XMLSchema-instance" ns1:schemaLocation="http://url/xml/ns/dblogs">\n\n <ns0:changeSet author="user_id" id="v3.0.0">\n\n <ns0:tagDatabase tag="release/v3.0.0" />\n\n </ns0:changeSet>\n\n <ns0:include file="./file_one.xml" />\n\n <ns0:include file="./file_two.xml" />\n\n<include>./dml/release/v3.0.0/abc_changelog.xml</include></ns0:dblogs

notice that in your code the tag is added as:

<include>./dml/release/v3.0.0/abc_changelog.xml</include>

To make it appear in the same manner as the others you also have to include the namespace (Emitting namespace specifications with ElementTree in Python) and the file argument (How do I add attributes to SubElement in ElementTree (Python))

answered Feb 19, 2024 at 12:23

Sebastian_Ulrich

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1 Comment

Hermann12 Over a year ago

You lost the namespace declaration.

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