Python FastAPI Framework
FastAPI is a modern, fast (high-performance), web framework for building APIs with Python 3.6+ based on standard Python type hints.
Installation
You need to install fastapi and an ASGI server, such as uvicorn.
pip install fastapi
pip install "uvicorn[standard]"Basic Application
Create a file main.py:
from fastapi import FastAPI
app = FastAPI()
@app.get("/")
def read_root():
return {"Hello": "World"}Running the Server
Run the server with:
uvicorn main:app --reloadmain: the filemain.py(the Python "module").app: the object created inside ofmain.pywith the lineapp = FastAPI().--reload: make the server restart after code changes.
Path Parameters
You can declare path "variables" or "parameters" with the same syntax used by Python format strings.
@app.get("/items/{item_id}")
def read_item(item_id: int):
return {"item_id": item_id}FastAPI uses type hints (item_id: int) to validate the data. If you visit /items/foo, you will get an HTTP error because "foo" is not an integer.
Query Parameters
When you declare other function parameters that are not part of the path parameters, they are automatically interpreted as "query" parameters.
@app.get("/items/")
def read_item(skip: int = 0, limit: int = 10):
return {"fake_items_db": [{"item_name": "Foo"}, {"item_name": "Bar"}][skip : skip + limit]}URL example: http://127.0.0.1:8000/items/?skip=0&limit=10
Request Body
To send data to your API, you use Pydantic models.
from typing import Optional
from fastapi import FastAPI
from pydantic import BaseModel
class Item(BaseModel):
name: str
price: float
is_offer: Optional[bool] = None
app = FastAPI()
@app.post("/items/")
def create_item(item: Item):
return itemAutomatic Documentation
FastAPI automatically generates interactive API documentation.
- Swagger UI: Go to
http://127.0.0.1:8000/docs. - ReDoc: Go to
http://127.0.0.1:8000/redoc.