### Direct mounting of routes
import pathlib

from fastapi import FastAPI, APIRouter
import uvicorn
import pydantic

class HelloRequest(pydantic.BaseModel):
    id: str


class HelloResponse(pydantic.BaseModel):
    hello: str


class Hello:
    def __init__(self, name: str) -> None:
        self.name = name

    async def handle(self, request: HelloRequest) -> HelloResponse:
        return HelloResponse(hello=self.name)

app = FastAPI()
hello_handler = Hello(name="test")
app.add_api_route("/hello", hello_handler.handle, methods=["POST"])






### Mounting of paths via Router
import pathlib

from fastapi import FastAPI, APIRouter
import uvicorn
import pydantic

class HelloRequest(pydantic.BaseModel):
    id: str


class HelloResponse(pydantic.BaseModel):
    hello: str


class Hello:
    def __init__(self, name: str) -> None:
        self.name = name

    async def handle(self, request: HelloRequest) -> HelloResponse:
        return HelloResponse(hello=self.name)


class RootRouter:
    def __init__(self, name: str):
        self.router = APIRouter()
        hello_handler = Hello(name=name)
        self.router.add_api_route("/hello", hello_handler.handle, methods=["POST"])


app = FastAPI()
root_router = RootRouter(name="test")
app.include_router(root_router.router)