FastAPI Project Templates

Production-ready FastAPI project structures with async patterns, dependency injection, middleware, and best practices for building high-performance APIs.

When to Use This Skill

• Starting new FastAPI projects from scratch
• Implementing async REST APIs with Python
• Building high-performance web services and microservices
• Creating async applications with PostgreSQL, MongoDB
• Setting up API projects with proper structure and testing

Core Concepts

1. Project Structure

Recommended Layout:

app/
├── api/                    # API routes
│   ├── v1/
│   │   ├── endpoints/
│   │   │   ├── users.py
│   │   │   ├── auth.py
│   │   │   └── items.py
│   │   └── router.py
│   └── dependencies.py     # Shared dependencies
├── core/                   # Core configuration
│   ├── config.py
│   ├── security.py
│   └── database.py
├── models/                 # Database models
│   ├── user.py
│   └── item.py
├── schemas/                # Pydantic schemas
│   ├── user.py
│   └── item.py
├── services/               # Business logic
│   ├── user_service.py
│   └── auth_service.py
├── repositories/           # Data access
│   ├── user_repository.py
│   └── item_repository.py
└── main.py                 # Application entry

2. Dependency Injection

FastAPI's built-in DI system using Depends:

• Database session management
• Authentication/authorization
• Shared business logic
• Configuration injection

3. Async Patterns

Proper async/await usage:

• Async route handlers
• Async database operations
• Async background tasks
• Async middleware

Detailed worked examples and patterns

Detailed sections (starting with ## Implementation Patterns) live in references/details.md. Read that file when the navigation summary above is insufficient.

Testing

# tests/conftest.py
import pytest
import asyncio
from httpx import AsyncClient
from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession
from sqlalchemy.orm import sessionmaker

from app.main  app
 app.core.database  get_db, Base

TEST_DATABASE_URL = 


 ():
    loop = asyncio.get_event_loop_policy().new_event_loop()
     loop
    loop.close()


  ():
    engine = create_async_engine(TEST_DATABASE_URL, echo=)
      engine.begin()  conn:
         conn.run_sync(Base.metadata.create_all)

    AsyncSessionLocal = sessionmaker(
        engine, class_=AsyncSession, expire_on_commit=
    )

      AsyncSessionLocal()  session:
         session


  ():
      ():
         db_session

    app.dependency_overrides[get_db] = override_get_db

      AsyncClient(app=app, base_url=)  client:
         client


 pytest


  ():
    response =  client.post(
        ,
        json={
            : ,
            : ,
            : 
        }
    )
     response.status_code == 
    data = response.json()
     data[] == 
       data