The xml module

The XML module comes with Python. In the following section we will focus on the two sub-modules minidom and ElementTree.

Working with minidom

In the following example we analyse books.xml:

<?xml version="1.0"?>
<catalog>
   <book id="1">
      <title>Python basics</title>
      <language>en</language>
      <author>Veit Schiele</author>
      <license>BSD-3-Clause</license>
      <date>2021-10-28</date>
   </book>
   <book id="2">
      <title>Jupyter Tutorial</title>
      <language>en</language>
      <author>Veit Schiele</author>
      <license>BSD-3-Clause</license>
      <date>2019-06-27</date>
   </book>
   <book id="3">
      <title>Jupyter Tutorial</title>
      <language>de</language>
      <author>Veit Schiele</author>
      <license>BSD-3-Clause</license>
      <date>2020-10-26</date>
   </book>
   <book id="4">
      <title>PyViz Tutorial</title>
      <language>en</language>
      <author>Veit Schiele</author>
      <license>BSD-3-Clause</license>
      <date>2020-04-13</date>
   </book>
</catalog>

1. To do this, we first import the minidom module and give it the same name so that it can be referenced more easily:

   import xml.dom.minidom as minidom
   

2. Then we define the method getTitles and capture the desired XML tags with the method getElementsByTagName:

   def getTitles(xml):
       """
       Print all titles found in books.xml
       """
       doc = minidom.parse(xml)
       node = doc.documentElement
       books = doc.getElementsByTagName("book")
   

3. Then we create an empty list called titles, which is filled with the title objects:

       titles = []
       for book in books:
           titleObj = book.getElementsByTagName("title")[0]
           titles.append(titleObj)
   

4. Now the title is output in nested for-loops:

       for title in titles:
           nodes = title.childNodes
           for node in nodes:
               if node.nodeType == node.TEXT_NODE:
                   print(node.data)
   

5. Finally, we set the __name__ variable like __main__ so that the module can be executed like the main program. Then we apply our getTitles method to our books.xml file:

   if __name__ == "__main__":
       document = "books.xml"
       getTitles(document)
   

Parsing with ElementTree

1. Importing cElementTree:

   import xml.etree.cElementTree as ET
   

   Note

   cElementTree written in C and is considerably faster than ElementTree.

2. Then we define the method parseXML and the root element:

   def parseXML(xml_file):
       """
       Parse XML with ElementTree
       """
       tree = ET.ElementTree(file=xml_file)
       print(tree.getroot())
       root = tree.getroot()
       print(f"tag={root.tag}, attrib={root.attrib}")
   

   <Element 'catalog' at 0x10b009620>
   tag=catalog, attrib={}
   

3. Output the XML child elements of book:

       for child in root:
           print(child.tag, child.attrib)
           if child.tag == "book":
               for step_child in child:
                   print(step_child.tag)
   

   book {'id': '1'}
   title
   language
   author
   license
   date
   book {'id': '2'}
   ...
   

4. Output the contents of the child elements with iter:

       print("-" * 20)
       print("Iterating using iter")
       print("-" * 20)
       books = root.iter()
       for book in books:
           book_children = book.iter()
           for book_child in book_children:
               print(f"{book_child.tag}={book_child.text}")
   

   --------------------
   Iterating using iter
   --------------------
   catalog=
   book=
   title=Python basics
   language=en
   author=Veit Schiele
   license=BSD-3-Clause
   date=2021-10-28
   book=
   title=Jupyter Tutorial
   ...