Usage with Starlette

Starlette has no dependency-injection system of its own, so modern-di-starlette uses the @inject decorator with FromDI markers (there is no Depends). setup_di composes the lifespan and installs middleware that opens a per-connection child container automatically.

How to use

1. Install modern-di-starlette

uvpip

uv add modern-di-starlette

pip install modern-di-starlette

2. Apply to your application

import dataclasses
import typing

from modern_di import Container, Group, Scope, providers
from modern_di_starlette import FromDI, inject, setup_di
from starlette.applications import Starlette
from starlette.requests import Request
from starlette.responses import JSONResponse
from starlette.routing import Route


@dataclasses.dataclass(kw_only=True)
class Settings:
    debug: bool = True


class AppGroup(Group):
    settings = providers.Factory(scope=Scope.APP, creator=Settings)


@inject
async def homepage(
    request: Request,
    settings: typing.Annotated[Settings, FromDI(AppGroup.settings)],
) -> JSONResponse:
    return JSONResponse({"debug": settings.debug})


app = Starlette(routes=[Route("/", homepage)])
setup_di(app, Container(groups=[AppGroup], validate=True))

3. Scopes

An HTTP request opens a Scope.REQUEST child container; a WebSocket connection opens a Scope.SESSION one. Providers resolve from the connection's child container, so Scope.REQUEST providers live for exactly one request.