Project 8: Build FastAPI (Modern Async Framework)
Build a minimal ASGI framework with async routing, validation, and dependency injection.
Quick Reference
| Attribute | Value |
|---|---|
| Difficulty | Advanced |
| Time Estimate | 3-4 weeks |
| Language | Python |
| Prerequisites | Asyncio, typing |
| Key Topics | ASGI, async routing, validation, DI |
| Output | Mini async API framework |
Learning Objectives
By completing this project, you will:
- Implement an ASGI application callable.
- Parse async request bodies and query params.
- Validate inputs using type hints or schemas.
- Add dependency injection for shared resources.
- Explain ASGI vs WSGI trade-offs.
The Core Question You’re Answering
“How do async APIs validate data and run efficiently under ASGI?”
Concepts You Must Understand First
| Concept | Why It Matters | Where to Learn |
|---|---|---|
| ASGI protocol | Scope/receive/send flow | ASGI spec |
| Async IO | Concurrency model | asyncio docs |
| Validation | Input safety | Pydantic docs |
| DI | Shared resources | FastAPI docs |
Project Specification
Functional Requirements
- Implement ASGI callable.
- Add route decorators for GET/POST.
- Parse JSON bodies from async events.
- Validate inputs and return 422 errors.
- Inject dependencies into handlers.
Implementation Guide
Project Structure
project-root/
├── fastapi_like/
│ ├── app.py
│ ├── routing.py
│ ├── validation.py
│ └── dependencies.py
└── demo.py
Questions to Guide Your Design
- How will you collect body chunks from ASGI events?
- How will you map type hints to validators?
- How will dependency resolution order work?
Testing Strategy
- Async route returns JSON.
- Invalid input returns 422.
- Dependency injection resolves correctly.
Extensions
- Add OpenAPI schema.
- Add middleware support.
- Add WebSocket endpoints.
This guide was generated from LEARN_DJANGO_WEB_FRAMEWORKS.md. For the complete learning path, see the parent directory LEARN_DJANGO_WEB_FRAMEWORKS/README.md.