Python Parsing XML Documents Using xmltodict

Introduction

XML (Extensible Markup Language) is a commonly used data exchange format that uses tags to describe the structure and content of data. Parsing XML documents becomes very important when dealing with XML files containing large amounts of data. Python is a powerful programming language that provides many libraries for parsing and processing XML. One of these is xmltodict.

xmltodict is a very convenient Python library that allows us to convert XML documents into Python dictionary structures, making them more convenient to manipulate and process. This article details how to use xmltodict to parse XML documents and provides some sample code to help you better understand.

Installing the xmltodict Library

Before using xmltodict, you need to install it. You can install the xmltodict library using the pip command:

pip install xmltodict

Parsing XML Documents

Parsing XML documents using the xmltodict library is very simple. Here are the basic parsing steps:
1. Import the xmltodict library:

import xmltodict

2. Open the XML file and read its contents:

with open('example.xml', 'r') as f:
xml_data = f.read()

3. Convert the XML data into a Python dictionary:

data_dict = xmltodict.parse(xml_data)

Now, we have successfully converted the XML document into a Python dictionary. We can access and manipulate the XML data by accessing the dictionary’s keys and values.

Reading XML Elements

In xmltodict, XML elements are converted to key-value pairs in a Python dictionary. You can read XML elements by accessing the dictionary keys.

The following is a sample XML document (example.xml):

<bookstore>
  <book category="cooking">
    <title lang="en">Everyday Italian</title>
    Giada De Laurentiis</author>
    <year>2005</year>
    <price>30.00</price>
  </book>
  <book category="children">
    <title lang="en">Harry Potter</title>
    J.K. Rowling</author>
    <year>2005</year>
    <price>29.99</price>
  </book>
  <book category="web">
    <title lang="en">Learning XML</title>
    Erik T. Ray</author>
    <year>2003</year>
    <price>39.95</price> </book>
</bookstore>

We can convert this to a Python dictionary using the following code:

import xmltodict

with open('example.xml', 'r') as f:
xml_data = f.read()

data_dict = xmltodict.parse(xml_data)

We can then read the corresponding XML elements by accessing the dictionary’s keys.

# Read the author of the first book
author = data_dict['bookstore']['book'][0]['author']
print(author)
# Output: Giada De Laurentiis

# Read the price of the second book
price = data_dict['bookstore']['book'][1]['price']
print(price)
# Output: 29.99

Modifying XML Elements

Using xmltodict, we can also modify the content of an XML document and save it as a new XML file.

The following example demonstrates how to change the category of the first book to “new_category” and save the modified XML document:

import xmltodict

with open('example.xml', 'r') as f:
xml_data = f.read()

data_dict = xmltodict.parse(xml_data)

# Change the category of the first book
data_dict['bookstore']['book'][0]['@category'] = 'new_category'

# Convert the dictionary back to an XML document
xml_content = xmltodict.unparse(data_dict)

# Save the modified XML document to a new file
with open('modified_example.xml', 'w') as f:
f.write(xml_content)

Now, we have successfully modified the XML document and saved it as a new XML file.

Summary

The xmltodict library makes it easy to parse and process XML documents. This article explains how to use it to parse XML documents and provides some sample code to help you better understand and use it. By learning and mastering the xmltodict library, you can more conveniently process and manipulate XML data.

References

• xmltodict Official Documentation