Writing and Reading XML config file in Python

We’ve already covered .ini, .json and .yaml in below articles, in this article we’ll focus on .xml config files.

• .ini file in Python
• .json file in Python
• .yaml file in Python

Reading and Writing config data to XML file in Python

XML, or eXtensible Markup Language is a markup language just like HTML that can be interpreted by both humans and computers easily. XML does not have predefined tags. For instance,

File: tutswiki.xml

<mail>
 <subject>
  config file
 </subject>
 <receiver>
  www.tutswiki.com
 </receiver>
 <content>
  This is an article
 </content>
</mail>

As we can see, all the tags used are user-defined which makes XML self-explanatory. We will be using the same file for reading and writing data.

For parsing the XML file, we will be using the BeautifulSoup module along with html parser. First, we need to install the latest BeautifulSoup4 package using the following command.

pip install BeautifulSoup4

We then have to import BeautifulSoup module from bs4 (BeautifulSoup4).

from bs4 import BeautifulSoup

Now, we are all set to parse our file.

Creating XML config file in Python

To add a new tag in our XML file tutswiki.xml, we use new_tag() method which takes an XML tag as a parameter. After creating a new tag, we use insert() method. This method takes 2 parameters, tag position, and the tag that we created earlier.

from bs4 import BeautifulSoup

with open("tutswiki.xml", "r") as f:
    content = f.read()
    y = BeautifulSoup(content, features="html.parser")
    new_tag = y.new_tag("h1")
    y.mail.insert(2,new_tag)
f = open("tutswiki.xml", "w")
f.write(y.prettify())

So we have created a tag h1 which will be inserted at position 2, i.e, after <subject>.

File: tutswiki.xml

<mail>
 <subject>
  config file
 </subject>
 <h1>
 </h1>
 <receiver>
  www.tutswiki.com
 </receiver>
 <content>
  This is an article
 </content>
</mail>

Here, prettify() method is used to convert the data into proper XML format. If we want to add attribute and content to the new tag, we write

new_tag.string = "This is a heading" # content
new_tag['name'] = 'heading' # attribute

which will get

<h1 name="heading">
  This is a heading
</h1>

Reading a key from XML config file

For reading, we will have to traverse to the tag which we want to read using the dot (.) operator. Let’s say we want to read the content of <h1> and the value of the attribute name.

from bs4 import BeautifulSoup

with open("tutswiki.xml", "r") as f:
    content = f.read()
    y = BeautifulSoup(content, features="html.parser")
    tag = y.mail.h1
    print(tag.string)
    print(tag['name'])

Here tag.string fetches the value inside the tag <h1>, and we get,

Output:

This is a heading
heading

Updating a key in XML config file

If we want to update tag name h1 to h2, we will use name property.

from bs4 import BeautifulSoup

with open("tutswiki.xml", "r") as f:
    content = f.read()
    y = BeautifulSoup(content, features="html.parser")
    tag = y.mail.h1
    tag.name = 'h2'
f = open("tutswiki.xml", "w")
f.write(y.prettify())

File: tutswiki.xml

<mail>
 <subject>
  config file
 </subject>
 <h2 name="heading">
  This is a heading
 </h2>
 <receiver>
  www.tutswiki.com
 </receiver>
 <content name="article">
  This is an article
 </content>
</mail>