Processing Files with Python

Python is a fantastic language for processing any kind of data. Its easy to learn and has a ton of libraries that make it easy to do just about anything. Let's use it to process our podcast files.

Create Your Repo

• RSS Feed Sample
• Guide

Let's take a look at that RSS feed so you can see why we're not trying to parse this ourselves.

RSS is a flavor of XML, so we start out by identifying the type of document the XML will be. The RSS tag has attributes and a link to the document that defines the structure of the file.

Then we have a series of tags. Sometimes the tags are simple like the channel tag and sometimes they have a colon in the name with an itunes prefix. Podcasts got their start as an Apple music player feature, that's why the itunes tag is all over the RSS feed.

I want to point out the category tag. This is a nested tag, which means that it has a child tag.

If you look at the description tag, you can see that it has a CDATA tag. This is a special tag that tells the parser that the data can have some HTML in it.

Also notice that sometimes the tags have attributes. Sometimes the data is enclosed in the tag, and sometimes it's in an attribute.

YAML File

We're not going to be creating every option for the RSS feed, just the ones we need. You can see how easy it is to write this in YAML.

YAML File

We're not going to be creating every option for the RSS feed, just the ones we need. You can see how easy it is to write this in YAML.

Installing

• Python Install
• PyYAML

In order to use this, we're going to need to make sure we have python installed as well as something that can help us parse the YAML file. We're going to use the PyYAML library. It will read the YAML file for us, convert it to an object we can work with and allow us to export the document.

Basic Parsing

import yaml # Import the PyYAML package
import xml.etree.ElementTree as xml_tree # Import the ElementTree module from the xml.etree package

# Load YAML data from file
with open('feed.yaml', 'r') as file:
    yaml_data = yaml.safe_load(file) # Use the safe_load() function to load the YAML data from the file

# Create RSS element with appropriate attributes and namespaces
rss_element = xml_tree.Element('rss', {'version': '2.0',
                                    'xmlns:itunes': 'http://www.itunes.com/dtds/podcast-1.0.dtd',
                                    'xmlns:content': 'http://purl.org/rss/1.0/modules/content/'})

channel_element = xml_tree.SubElement(rss_element, 'channel') # Create channel element as a child of the RSS element
link_prefix = yaml_data['link'] # Store the link prefix in a variable for convenience

# Add subelements to the channel element using data from the YAML file
xml_tree.SubElement(channel_element, 'link').text = link_prefix
xml_tree.SubElement(channel_element, 'format').text = yaml_data['format']
xml_tree.SubElement(channel_element, 'title').text = yaml_data['title']
xml_tree.SubElement(channel_element, 'subtitle').text = yaml_data['subtitle']
xml_tree.SubElement(channel_element, 'itunes:author').text = yaml_data['author']
xml_tree.SubElement(channel_element, 'description').text = yaml_data['description']
xml_tree.SubElement(channel_element, 'itunes:image', {'href': link_prefix + yaml_data['image']})
xml_tree.SubElement(channel_element, 'language').text = yaml_data['language']
xml_tree.SubElement(channel_element, 'itunes:explicit').text = yaml_data['explicit']
xml_tree.SubElement(channel_element, 'link').text = link_prefix

# Create an 'itunes:category' subelement within the 'channel' element, and set its 'text' attribute to the value of the 'category' field from the YAML data
category = xml_tree.SubElement(channel_element, 'itunes:category', {'text': yaml_data['category']})

# Loop through each item in the YAML file's 'item' section, and add an 'item' subelement to the channel element for each one
for item in yaml_data['item']:
    item_element = xml_tree.SubElement(channel_element, 'item')
    xml_tree.SubElement(item_element, 'title').text = item['title']
    xml_tree.SubElement(item_element, 'itunes:author').text = yaml_data['author']
    xml_tree.SubElement(item_element, 'description').text = item['description']
    xml_tree.SubElement(item_element, 'itunes:duration').text = item['duration']
    xml_tree.SubElement(item_element, 'pubDate').text = item['published']
    
    # Add an 'enclosure' subelement to the 'item' element, 
    # which specifies the audio file associated with this item
    enclosure = xml_tree.SubElement(item_element, 'enclosure', {
        'url': link_prefix + item['file'],
        'type': 'audio/mpeg',
        'length': item['length']
    })

# Write the created XML tree to a file
output_tree = xml_tree.ElementTree(rss_element) # Create an ElementTree object from the RSS element
output_tree.write('podcast.xml', encoding='UTF-8', xml_declaration=True) # Write the XML tree to a file