modern-di-fastapi

Modern-DI integration for FastAPI.

Usage example: fastapi-sqlalchemy-template

Installation

uv add modern-di-fastapi      # or: pip install modern-di-fastapi

Usage

setup_di registers the container and builds a per-request child container automatically; FromDI resolves a provider (or type) into a route parameter.

import dataclasses

import fastapi
from modern_di import Container, Group, Scope, providers
from modern_di_fastapi import FromDI, setup_di


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


@dataclasses.dataclass(kw_only=True)
class UserService:
    settings: Settings  # auto-injected by type


class Dependencies(Group):
    settings = providers.Factory(scope=Scope.APP, creator=Settings)
    user_service = providers.Factory(scope=Scope.REQUEST, creator=UserService)


app = fastapi.FastAPI()
container = Container(groups=[Dependencies], validate=True)
setup_di(app, container)


@app.get("/")
async def index(user_service: UserService = FromDI(Dependencies.user_service)) -> dict[str, bool]:
    return {"debug": user_service.settings.debug}

The framework Request / WebSocket are resolvable within DI via the pre-built fastapi_request_provider / fastapi_websocket_provider context providers.

API

Symbol	Description
setup_di(app, container)	Stores the container on app.state and appends a lifespan that closes it on shutdown (merges with any existing lifespan=)
FromDI(provider, *, use_cache=True)	FastAPI Depends that resolves a provider (or type) from the per-request child container
fetch_di_container(app)	Returns the app-scoped container from app.state
build_di_container(connection)	FastAPI Depends callable that yields the per-request child container — REQUEST scope for an HTTP request, SESSION scope for a WebSocket
fastapi_request_provider	ContextProvider for the current fastapi.Request
fastapi_websocket_provider	ContextProvider for the current fastapi.WebSocket

📦 PyPI

📝 License

Part of modern-python

Browse the full list of templates and libraries in modern-python — see the org profile for the categorized index.