Bigger Applications - Multiple Files
Part of: FastAPI Basics
Learn to structure larger FastAPI applications using APIRouter, multiple files, and proper Python package organization.
What You'll Learn
- Understand how to structure larger FastAPI applications
- Learn to use APIRouter for modular routing
- Implement proper Python package structure with __init__.py files
- Use relative imports between modules
- Organize dependencies and routers across multiple files
Theory and Concepts
Bigger Applications - Multiple Files
🎯 What You'll Learn
- How to structure larger FastAPI applications using multiple files
- Using APIRouter to organize routes into modules
- Understanding Python package structure with __init__.py files
- Implementing relative imports between modules
- Organizing dependencies and sharing them across routers
📚 Theory
When building real-world applications, putting everything in a single file becomes unwieldy. FastAPI provides excellent tools to organize your code into multiple files while maintaining all the flexibility and features you need.
Project Structure
The recommended structure for larger FastAPI applications follows Python package conventions:
[Code Example]
Key Concepts
1. APIRouter
APIRouter is like a "mini FastAPI" that you can use to organize related routes:
[Code Example]
2. Router Configuration
You can configure routers with common settings:
[Code Example]
3. Including Routers
In your main application, include routers:
[Code Example]
4. Relative Imports
Use relative imports to access modules within your package:
[Code Example]
5. Dependencies Across Modules
Dependencies can be shared across the entire application or specific routers:
[Code Example]
🔧 Key Concepts
- APIRouter: Organizes related routes into modules
- Package Structure: Use __init__.py files to create Python packages
- Relative Imports: Navigate between modules using . and .. syntax
- Router Inclusion: Use app.include_router() to add routers to your main app
- Dependency Sharing: Apply dependencies at app, router, or route level
💡 Best Practices
1. Group Related Routes: Put related functionality in the same router
2. Use Prefixes: Apply common URL prefixes at the router level
3. Share Dependencies: Define common dependencies once and reuse them
4. Organize by Feature: Structure your code by business logic, not technical layers
5. Keep Main App Simple: The main app should primarily orchestrate routers
🔗 Additional Resources
- FastAPI Bigger Applications Documentation
- Python Packages and Modules
- APIRouter Reference
Helpful Hint
Use APIRouter to create modular route handlers, then include them in your main FastAPI app with app.include_router(). Don't forget __init__.py files to make directories into Python packages!