FastAPI Tutorial - Getting Started
FastAPI is a modern, fast (high-performance), web framework for building APIs with Python 3.8+ based on standard Python type hints.
Key Features
- Fast: Very high performance, on par with NodeJS and Go (thanks to Starlette and Pydantic).
- Fast to code: Increase the speed to develop features by about 200% to 300%.
- Fewer bugs: Reduce about 40% of developer induced errors.
- Intuitive: Great editor support. Completion everywhere. Less time debugging.
- Easy: Designed to be easy to use and learn. Less time reading documentation.
- Short: Minimize code duplication. Multiple features from each parameter declaration.
- Robust: Get production-ready code. With automatic interactive documentation.
- Standards-based: Based on (and fully compatible with) the open standards for APIs: OpenAPI and JSON Schema.
Installation
Install FastAPI and Uvicorn (an ASGI server) using pip:
pip install fastapi uvicorn
Basic Application Creation
Create a file named main.py with:
from fastapi import FastAPI
app = FastAPI()
@app.get("/")
def read_root():
return {"Hello": "World"}
@app.get("/items/{item_id}")
def read_item(item_id: int, q: str = None):
return {"item_id": item_id, "q": q}
Running the Application
Start the development server with:
uvicorn main:app --reload
The --reload flag enables auto-reloading of the server when files change.
OpenAPI Documentation
FastAPI automatically generates interactive API documentation. You can access it at:
- Swagger UI:
http://127.0.0.1:8000/docs - ReDoc:
http://127.0.0.1:8000/redoc