150. XML Parsing with ElementTree

Here are 10 Python code snippets demonstrating XML parsing and creation using Python's xml.etree.ElementTree module. These examples will guide you through different tasks like parsing XML files, creating XML data, and manipulating XML structures.

1. Parsing XML from a String

This example shows how to parse an XML string and extract elements.

import xml.etree.ElementTree as ET

xml_data = '''<person>
    <name>John</name>
    <age>30</age>
    <city>New York</city>
</person>'''

root = ET.fromstring(xml_data)
print(root.tag)  # person
print(root.find('name').text)  # John
print(root.find('age').text)  # 30

Explanation:

• fromstring() is used to parse an XML string into an Element object.

• The find() method locates a sub-element by tag.

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2. Parsing XML from a File

This snippet demonstrates how to parse XML from a file.

import xml.etree.ElementTree as ET

tree = ET.parse('example.xml')
root = tree.getroot()
for child in root:
    print(child.tag, child.text)

Explanation:

• parse() reads an XML file and returns an ElementTree object.

• getroot() fetches the root element, and you can iterate over all child elements.

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3. Creating XML Structure

Create an XML document from scratch.

import xml.etree.ElementTree as ET

root = ET.Element('person')
name = ET.SubElement(root, 'name')
name.text = 'John'
age = ET.SubElement(root, 'age')
age.text = '30'

tree = ET.ElementTree(root)
tree.write('output.xml')

Explanation:

• Element() creates the root element, and SubElement() adds child elements.

• write() saves the XML tree to a file.

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4. Modifying XML Elements

This example shows how to modify an existing XML element.

import xml.etree.ElementTree as ET

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

# Modify the first 'name' element
root.find('name').text = 'Alice'

tree.write('modified.xml')

Explanation:

• The find() method locates a specific element, and its text value is updated.

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5. Adding Attributes to XML Elements

Demonstrates how to add attributes to XML elements.

import xml.etree.ElementTree as ET

root = ET.Element('person')
name = ET.SubElement(root, 'name', {'lang': 'en'})
name.text = 'John'

tree = ET.ElementTree(root)
tree.write('output_with_attributes.xml')

Explanation:

• Attributes are added to elements by passing a dictionary as a second argument to SubElement().

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6. Removing an Element from XML

Remove an element from an XML structure.

import xml.etree.ElementTree as ET

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

# Remove the 'age' element
age_element = root.find('age')
root.remove(age_element)

tree.write('output_without_age.xml')

Explanation:

• The remove() method is used to delete an element from the XML tree.

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7. Searching for Elements with XPath

Using findall() to search for multiple elements that match an XPath-like expression.

import xml.etree.ElementTree as ET

xml_data = '''<people>
    <person>
        <name>John</name>
        <age>30</age>
    </person>
    <person>
        <name>Alice</name>
        <age>25</age>
    </person>
</people>'''

root = ET.fromstring(xml_data)

# Find all 'person' elements
for person in root.findall('person'):
    name = person.find('name').text
    age = person.find('age').text
    print(f'{name} is {age} years old')

Explanation:

• findall() returns all matching elements.

• XPath-like expressions can be used to locate nested elements.

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8. Pretty-Printing XML

Pretty-print XML data with indentation.

import xml.etree.ElementTree as ET
from xml.dom import minidom

root = ET.Element('person')
name = ET.SubElement(root, 'name')
name.text = 'John'
age = ET.SubElement(root, 'age')
age.text = '30'

# Generate XML string
xml_str = ET.tostring(root, 'utf-8')
parsed_str = minidom.parseString(xml_str)
pretty_str = parsed_str.toprettyxml(indent="  ")

print(pretty_str)

Explanation:

• minidom.parseString() is used to prettify the XML string.

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9. Handling Namespaces in XML

Parsing XML that contains namespaces.

import xml.etree.ElementTree as ET

xml_data = '''<person xmlns="http://example.com">
    <name>John</name>
    <age>30</age>
</person>'''

namespaces = {'ns': 'http://example.com'}
root = ET.fromstring(xml_data)

# Accessing element with namespace
name = root.find('ns:name', namespaces).text
print(name)  # John

Explanation:

• A dictionary is passed to find() to handle namespaces.

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10. Serializing XML to a String

Serialize an Element to a string format.

import xml.etree.ElementTree as ET

root = ET.Element('person')
name = ET.SubElement(root, 'name')
name.text = 'John'
age = ET.SubElement(root, 'age')
age.text = '30'

# Convert the tree to a string
xml_str = ET.tostring(root, encoding='unicode')
print(xml_str)

Explanation:

• tostring() serializes the XML tree to a string.

• The encoding='unicode' argument ensures the output is a string, not bytes.

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These examples cover various aspects of XML parsing and manipulation in Python using the xml.etree.ElementTree module, including creating XML from scratch, modifying existing XML, searching for elements, handling namespaces, and more.