modern-di

name

modern-di

description

Reference guide for the modern-di Python DI framework. Use this skill for ANY question about modern-di — scope hierarchy (Scope.APP/REQUEST/SESSION/ACTION), Group/Factory/CacheSettings declaration, Container resolution (resolve vs resolve_provider, build_child_container), ContextProvider for runtime values, framework integration via ModernDIPlugin or setup_di/FromDI, testing with container.override/reset_override, injecting Request objects into providers, and SQLAlchemy session wiring. Trigger on: modern-di, providers.Factory, CacheSettings, Scope.REQUEST, Scope.APP, build_child_container, ModernDIPlugin, setup_di, modern-di-litestar, modern-di-fastapi, container.override, resolve_provider. Don't skip this skill for questions that seem simple — modern-di has specific idioms (no Singleton class, sync-only resolution, hierarchical scopes) that differ from other DI frameworks.

modern-di Skill

modern-di is a zero-dependency Python DI framework. It wires object graphs from type annotations, manages lifetimes through hierarchical scopes, and supports sync/async finalizers.

Navigation

This skill is split across focused reference files. Read the one that matches the task:

File	When to read it
common.md	Core concepts: Group, Factory, Container, Scope, CacheSettings, ContextProvider
litestar.md	Litestar integration: ModernDIPlugin, FromDI, route handlers
fastapi.md	FastAPI integration: setup_di, FromDI, route handlers
testing.md	Testing: overrides, scope chains, pytest fixtures

Read common.md first if the user is new to modern-di. For framework-specific questions, go directly to litestar.md or fastapi.md. For testing questions, read testing.md (and common.md if needed for context).

Quick reference

from modern_di import Container, Group, Scope, providers

class Dependencies(Group):
    db_engine = providers.Factory(
        scope=Scope.APP,
        creator=create_async_engine,
        cache_settings=providers.CacheSettings(finalizer=close_engine),
    )
    session = providers.Factory(
        scope=Scope.REQUEST,
        creator=create_session,
        cache_settings=providers.CacheSettings(finalizer=close_session),
    )

container = Container(scope=Scope.APP, groups=[Dependencies])

Common errors

Error	Fix
Provider of type X not registered	Add providers.Factory(creator=X) to your Group
Provider of scope REQUEST cannot be resolved in container of scope APP	Build a child container first
Provider is duplicated by type X	Set bound_type=None on one of the conflicting providers
Argument X of type Y cannot be resolved	Register a provider for that type or pass via kwargs