How to Save Web Pages and Subpages as a .CHM File in Python

Introduction to CHM Files

Compiled HTML Help (CHM) files are a common format for delivering digital documentation and help files on Windows. These files bundle together HTML pages, images, and other resources into a single file that can be easily viewed and shared. CHM files are particularly useful for software documentation, tutorials, and technical content because they allow for a structured presentation of information while ensuring convenience for the end user.

In this tutorial, we will explore how to save web pages and their subpages into a .CHM file using Python. This process involves fetching the necessary content, organizing it correctly, and finally converting it into a CHM format that maintains the hierarchy of the web pages while being accessible in a user-friendly manner.

By the end of this guide, you will learn how to use Python libraries to automatically download web content and embed it into a CHM file, making it a great tool for developers and content writers who need to package their work for easier distribution.

Prerequisites

Before we dive into the coding part, ensure that you have the following tools installed on your machine:

Python 3.x: The latest version of Python must be installed. You can download it from the official website.
Libraries: We will need libraries like requests for fetching web content and pychm (used for creating .CHM files). Install these libraries via pip:

pip install requests pychm

You also need a basic understanding of HTML and Python programming concepts for better navigation through this tutorial.

Fetching Web Pages with Python

The first step in creating a .CHM file is to gather the web pages and their subpages that you want to include. Python’s requests library makes this process straightforward. We can use it to send GET requests to a URL and retrieve the HTML content.

Here is an example of how you can fetch a web page using the requests library:

import requests

url = 'https://example.com'
response = requests.get(url)

doc = response.text
print(doc)

In this snippet, we retrieve the HTML content of a web page and print it to the console. You can save this content into a variable for further processing. However, if you want to embrace all subpages, you will need a strategy to find and download them too.

To accomplish this, we would typically parse the HTML with libraries like BeautifulSoup to locate all the links within the page. Here’s an example of how to do this:

from bs4 import BeautifulSoup

soup = BeautifulSoup(doc, 'html.parser')
links = soup.find_all('a')

for link in links:
    sub_url = link.get('href')
    if sub_url and sub_url.startswith('http'):
        sub_response = requests.get(sub_url)
        # Process this sub_response similar to the main page

In this code, we grab all anchor tags and filter through their href attributes to find usable links. We can continue this process recursively to cover multiple layers of subpages.

Organizing the Content

Once you have gathered all the relevant HTML content, the next step is to organize it in a manageable structure. Creating a directory to hold your HTML files would be an effective way to keep everything organized. This structure can also mirror how you want the content to be presented in the .CHM file.

You can save each page into a file with a simple Python function:

import os

def save_html(content, filename):
    if not os.path.exists('output'):
        os.makedirs('output')
    with open(os.path.join('output', filename), 'w', encoding='utf-8') as f:
        f.write(content)

Once you have the content saved in an output directory, you can format the names of your files according to your preferred structure. It’s helpful to use meaningful names that indicate the hierarchy of the subpages.

Consider naming your index.html as the main file and following with a clear and structured naming convention for subpages, for instance, subpage1.html, subpage2.html, etc. This naming will assist you in ensuring that the .CHM file represents the sections logically.

Creating the .CHM File

The pychm library allows us to create .CHM files easily by providing the content and settings. To create the .CHM file, you first create an instance of the CHM class and then add your files to it.

import pychm

chm = pychm.PYCHM()
chm.add_file('output/index.html', 'index.html')
chm.add_file('output/subpage1.html', 'subpage1.html')
# Add additional files as necessary

After you’ve added all files, you can save the CHM file using this code:

chm.save('output/documentation.chm')

This code saves your compiled HTML Help file in the specified output directory, encapsulating all the HTML pages you created. You can open the .CHM file directly in Windows to see your neatly organized documentation.

Testing the .CHM File

Once you have generated the .CHM file, it’s time to test it. Open the file in CHM viewer on Windows to check if all pages and links are functioning properly. The structure you set in the Python script should be mirrored in the viewer.

It’s essential to ensure that all subpages are correctly linked and accessible from the main index HTML. If any links fail to work, review the saving and linking logic in your Python code. You may need to double-check that all required files were correctly listed during the generation of the CHM file.

Testing is crucial to ensure a seamless user experience. Check for not just functionality but also layout and design within the different HTML pages in the CHM. Visual continuity will enhance the professionalism of your documentation.

Conclusion

In this comprehensive guide, we walked through the entire process of fetching web pages, organizing the content, and finally compiling it into a .CHM file using Python. You should now have a good understanding of how to automate this process and create reusable code for future projects.

The ability to bundle information into a .CHM format can be a game-changer for software documentation and tutorials. With a structured layout, you can provide users with a better experience while improving the accessibility of your content.

Keep experimenting with Python, and don’t hesitate to incorporate more features like styling your HTML pages or adding functionality with JavaScript. Happy coding!