DEV Community

🚀 Building a Flask RESTful API: From Jinja2 Views to a Scalable Backend

In this post, I’ll walk you through how I transitioned my Flask project from a classic Jinja2-based web app to a modular, production-ready backend with a RESTful API, full test coverage, and Swagger documentation.

🧠 Motivation: I wanted to go beyond basic templating and learn how to build backends that scale, integrate with frontend frameworks, and support proper testing and documentation.


swagger (Flasgger)

🔧 Technologies Used

  • Python 3.12

  • Flask with Blueprint architecture

  • SQLite + SQLAlchemy ORM

  • Flasgger (Swagger UI integration)

  • Jinja2 for server-rendered views

  • Pytest for automated testing

  • Postman for manual endpoint verification

  • Git for version control

💡 What I Built

  • 🔄 A full RESTful API for task management

  • 🧩 Clean code structure with an app factory (create_app) and Blueprint registration

  • 🧪 Unit tests using Pytest with in-memory SQLite

  • 📘 Interactive API docs with Swagger

  • 🧼 Better endpoint handling using unique endpoint= values to resolve route conflicts

  • 🧠 JSON-based error responses and safe exception management

Test Unitarios

✅ Results

  • Swagger now correctly renders all documented endpoints.

  • All tests pass reliably across isolated app instances.

  • The backend is ready to be consumed by frontend frameworks like React.

  • All source code and documentation are publicly available via my portfolio.

🔗 Check it out: nicolasandrescl.pythonanywhere.com 🧪 The code is already deployed as a static asset and will soon go live as a full API service.

🎯 Next Steps

  • Add JWT authentication

  • Connect a React frontend

  • Enable pagination and filtering

  • Deploy to production with metrics

If you're learning Flask or building your first API, feel free to check out the repo and reach out—happy to collaborate and grow with the community!

Python #Flask #RESTAPI #Swagger #Pytest #DeveloperJourney #WebDevelopment #Backend #SQLAlchemy #PortfolioProject

Top comments (0)