How to Read Source Code: Frappe Framework Sample

Reading source code is a superpower for any developer. Whether you want to contribute to open-source, debug an issue, or just satisfy your curiosity about how your favorite tools work under the hood, being able to navigate and understand a large codebase is essential.

In this post, I’ll share a practical guide to reading source code, using the Frappe Framework (the engine behind ERPNext) as a real-world example.

⭐ General Guidelines for Reading Source Code

Before diving into any specific project, here are some universal strategies that will help you with Frappe—or any large codebase:

Start With the Documentation
- Skim the README, wikis, and official docs to get the project’s purpose and main components.
Map Out the Big Pieces
- Quickly scan the folder structure and look for main modules, entry points, and naming conventions.
Don’t Try to Read Everything
- Focus on the parts relevant to your current task or question. Skim for function/class names and docstrings.
Trace a Feature End-to-End
- Pick a simple action (like “create document” or “login”) and follow its flow from UI to backend.
Follow the Data
- Watch how information moves: from API calls to model/database, to output/response.
Leverage Tools
- Use your IDE’s search, jump-to-definition, and reference-finding tools.
- Use logging or print() statements to see what runs.
Look for Tests and Examples
- Tests often provide practical examples of how the code is supposed to work.
Make Diagrams or Notes
- As you go, draw simple flowcharts or write summaries to clarify your understanding.
Ask and Engage
- Don’t hesitate to ask the community or look for related questions on GitHub, Stack Overflow, or forums.
Practice Regularly
- The more projects you explore, the faster and more intuitive this process becomes!

1. Start With the Big Picture

Before you open any files, skim the README and documentation. For Frappe, the official docs and GitHub README will give you an overview of what the framework does, its architecture, and how modules fit together.

2. Map Out the Folder Structure

Open the repo in your favorite editor. Here’s what you’ll see in the Frappe root folder:

frappe/
├── app.py
├── desk/
├── core/
├── model/
├── utils/
├── public/
├── website/
├── workflow/
└── ...

app.py: The web app entry point (WSGI).
desk/: The admin UI (Desk) logic and pages.
core/: User, role, permission, session, and other essential modules.
model/: ORM and DocType logic.
utils/: Utility functions.
workflow/: Workflow engine logic.

Tip: Read the comments or __init__.py files in each folder for high-level hints.

3. Find the Entry Point

For web apps like Frappe, this is often app.py or wsgi.py. In Frappe, frappe/app.py defines the WSGI application:

application = get_wsgi_application()

When you start Frappe (via Docker, Bench, or otherwise), this is the first code that runs for web requests.

4. Trace a Simple Flow

Let’s say you want to understand how a “Task” document loads in Desk:

The user navigates to the Task form.
The Desk frontend (JS in public/js/frappe/desk/) makes an API call to load the document.
The backend API route is handled in frappe/desk/form/load.py (getdoc function).
The ORM logic in frappe/model/document.py fetches the document from the database.

Pro tip: Use your IDE’s “go to definition” or “find all references” feature to jump between functions and classes.

5. Look for Config and Hooks

Frappe’s extensibility comes from its hooks.py files, which let you plug in new logic, event handlers, and UI assets.
If you want to see how modules interact or how custom code is loaded, start here.

6. Read the Tests

Tests are living documentation!
Check the /tests/ or /testing/ folders for real examples of how APIs and modules are used.

7. Don’t Read Everything—Scan and Skim

Look for:

Function/class names and docstrings
Comments and TODOs
High-level structure
Only deep-dive into code that’s directly relevant to your question

8. Use the Application

Nothing helps more than running the app locally:

Use the UI, trigger actions, and watch the logs/console for clues.
Add print() statements or use the debugger to step through the flow.

Conclusion

Reading source code is like exploring a new city—use a map (docs), ask locals (community, comments), and don’t be afraid to get a little lost!
With practice, you’ll become faster at picking up patterns and understanding even the most complex frameworks.

Happy coding, and may your journey through Frappe’s codebase be an enlightening one!