FastAPI :: OpenAPI or Swagger

1.py

from fastapi import FastAPI

app = FastAPI()

@app.get("/", tags=["Main"])
async def root():
    return {"message": "Hello World"}

@app.get("/products/{product_id}", tags=["Product"])
async def get_product(product_id: int):
    return {"product_id": product_id}

@app.post("/products/", tags=["Product"])
async def create_product(product: dict):
    return {"product": product}

@app.put("/users/{user_id}", tags=["User"])
async def update_user(user_id: int):
    return {"user_id": user_id}

2.py

from enum import Enum
class Tags(Enum):
    Main = "Main"
    Product = "Product"
    User = "User"
    
 
@app.get("/", tags=[Tags.Main])
@app.get("/products/{product_id}", tags=[Tags.Product])
@app.post("/products/", tags=[Tags.Product])
@app.put("/users/{user_id}", tags=[Tags.User])

3.py

from fastapi import FastAPI

// Sub API
subapi = FastAPI()
@subapi.get("/extra/")
async def read_extra():
    return {"message": "Hello Extra"}

// Main app
app = FastAPI()
@app.get("/", tags=[Tags.Main])
@app.get("/products/{product_id}", tags=[Tags.Product])

// Mount
app.mount("/extra", subapi)