ch03-first-api/main.py

from typing import Optional

import fastapi
import uvicorn

api = fastapi.FastAPI()


@api.get('/')
def index():
    body = (
        '<html>'
        "<body style='padding: 10px;'>"
        '<h1>Welcome to the API</h1>'
        '<div>'
        "Try it: <a href='/api/calculate?x=7&y=11'>/api/calculate?x=7&y=11</a>"
        '</div>'
        '</body>'
        '</html>'
    )

    return fastapi.responses.HTMLResponse(content=body)


@api.get('/api/calculate')
def calculate(x: int, y: int, z: Optional[int] = None):
    if z == 0:
        return fastapi.responses.JSONResponse(content={'error': 'ERROR: Z cannot be zero.'}, status_code=400)

    value = x + y

    if z is not None:
        value /= z

    return {'x': x, 'y': y, 'z': z, 'value': value}


# uvicorn was updated, and it's type definitions don't match FastAPI,
# but the server and code still work fine. So ignore PyCharm's warning:
# noinspection PyTypeChecker
uvicorn.run(api, port=8000, host='127.0.0.1')