alti3/litestar-plugins

Plugins

Use this skill when a Litestar app needs plugin-driven behavior, or when the task touches one of the model ecosystems that Litestar integrates through plugins, DTO factories, or OpenAPI schema plugins.

Current Docs Mapping

The links previously listed for this skill are partly stale in the latest Litestar docs. Use the current structure below:

• Core plugin architecture is documented at usage/plugins/index.html.
• SQLAlchemy plugin docs moved under usage/databases/sqlalchemy/plugins/....
• Piccolo is documented in latest docs as PiccoloDTO usage under usage/databases/piccolo.html, not as a separate general plugin page.
• Pydantic and attrs support in latest docs is primarily reference-driven under reference/plugins/....
• Dataclass and msgspec support in latest docs is documented as DTO factories under reference/dto/..., not as standalone plugin usage pages.
• Latest docs do not expose a dedicated TypedDict plugin page. Treat TypedDict as a typing/schema concern unless project-local code proves otherwise.

Do not blindly follow old usage/plugins/*.html URLs for every ecosystem. Several now return 404 in the latest docs.

Execution Workflow

1. Start from the desired outcome: app initialization, dependency injection help, automatic DTO generation, ORM session management, or OpenAPI schema support.
2. Decide whether the problem needs a true Litestar plugin protocol implementation or only an ecosystem DTO/OpenAPI integration.
3. Register the minimum plugin set needed in Litestar(..., plugins=[...]), and keep ordering explicit.
4. Prefer explicit dto / return_dto declarations when the public contract matters more than boilerplate reduction.
5. Validate request parsing, response serialization, dependency injection, and generated OpenAPI together.
6. Add focused tests for the exact supported annotation shapes: single model, collection, wrapper, PATCH flow, and dependency injection edge cases.

Core Plugin Protocols

InitPlugin

Use for application composition and startup-time configuration.

• Implements on_app_init(self, app_config: AppConfig) -> AppConfig.
• Runs after application on_app_init hooks.
• Runs in the same order as the plugins=[...] list.
• Appropriate for injecting dependencies, registering route handlers, middleware, exception handlers, or app-wide config.

Use this when the plugin changes application structure.

SerializationPluginProtocol

Use when Litestar should auto-create DTOs for supported handler annotations.

• Implement supports_type(field_definition) -> bool.
• Implement create_dto_for_type(field_definition) -> type[AbstractDTO].
• Litestar uses the plugin only when an annotation is supported and the handler does not already define dto or return_dto.

Use this for reducing repeated DTO declarations, not for hiding contract decisions.

DIPlugin

Use when Litestar needs help understanding constructor type information for dependency injection.

• Implement has_typed_init(type_) -> bool.
• Implement get_typed_init(type_) -> tuple[Signature, dict[str, Any]].

Use this for model types whose constructor annotations are not directly recoverable by default inspection.

ReceiveRoutePlugin

Use when a plugin must observe routes during registration.

• Implements receive_route(route: BaseRoute) -> None.
• Good for route validation, route metadata collection, or derived registration side effects.

Keep this observational. Do not bury broad app mutation here.

OpenAPISchemaPluginProtocol

Use when a non-native model/type needs custom OpenAPI schema generation.

• Implement is_plugin_supported_type(value) -> bool.
• Implement to_openapi_schema(field_definition, schema_creator) -> Schema.

Use this for schema generation, not request parsing or DTO mutation.

Selection Guide

Choose the smallest surface that solves the problem:

• Need to mutate AppConfig or install app-wide behavior: use an InitPlugin.
• Need automatic DTOs for specific model annotations: use a serialization plugin.
• Need constructor introspection for DI: use a DIPlugin.
• Need OpenAPI support for a model ecosystem: use a schema plugin.
• Need ORM request/session lifecycle: use the ORM ecosystem’s init/full plugin.
• Need only payload shaping for a model ecosystem: use explicit DTO classes instead of broad plugins.

Ecosystem Guidance

SQLAlchemy

Latest docs still show imports from litestar.plugins.sqlalchemy, but the class reference material is now largely hosted through Advanced Alchemy.

Primary choices:

• SQLAlchemyPlugin(config=...): full integration; combines init behavior and serialization support.
• SQLAlchemyInitPlugin(config=...): session/engine lifecycle and DI only.
• SQLAlchemySerializationPlugin(): auto-generates SQLAlchemyDTO[...] for supported annotations when no explicit DTO is declared.
• SQLAlchemyDTO[Model]: explicit DTO when you need contract control.

SQLAlchemyInitPlugin behavior in latest docs:

• Makes engine and session injectable.
• Stores engine and session factory in application state.
• Configures a before_send handler.
• Adds relevant names to the signature namespace.

Configuration rules:

• Use SQLAlchemyAsyncConfig for async engines/sessions.
• Use SQLAlchemySyncConfig for sync engines/sessions.
• Sync handlers using SQLAlchemy sessions should generally set sync_to_thread=True.
• Customize dependency names with engine_dependency_key and session_dependency_key if defaults conflict.
• Customize cleanup and transaction behavior with before_send_handler.
• Use the autocommit handlers only when request-scoped commit-on-success / rollback-on-error matches the app’s transaction model.
• Use engine_config and session_config for lower-level SQLAlchemy tuning instead of ad hoc patching.

Serialization rules:

• SQLAlchemySerializationPlugin is functionally equivalent to explicit SQLAlchemyDTO[...] declarations for supported annotations.
• Explicit DTOs still win when you need DTOConfig, separate read/write policies, field exclusions, or PATCH semantics.
• Mark fields and DTO config deliberately. The serialization plugin is not a substitute for contract review.

Piccolo

Latest docs focus on litestar.contrib.piccolo.PiccoloDTO rather than a dedicated plugin page.

Use Piccolo support like this:

• dto=PiccoloDTO[Table]
• return_dto=PiccoloDTO[Table]
• PATCH via a subclass with DTOConfig(exclude={"id"}, partial=True) and DTOData[Table].update_instance(...)

Guidance:

• Treat Piccolo as a DTO integration first, not a general-purpose plugin stack.
• Manage table creation, connection lifecycle, and broader persistence architecture through normal startup/database patterns.
• If the task is mainly persistence design, hand off to litestar-databases.

Pydantic

Latest docs expose a broader plugin surface here than for most other model ecosystems.

Available pieces:

• PydanticPlugin: broad app integration for Pydantic.
• PydanticInitPlugin: init-focused integration.
• PydanticDIPlugin: DI constructor/signature support.
• PydanticDTO[T]: explicit DTO support for Pydantic models.
• PydanticSchemaPlugin: OpenAPI schema generation.

Important PydanticPlugin / PydanticInitPlugin options:

• exclude
• include
• exclude_defaults
• exclude_none
• exclude_unset
• prefer_alias
• validate_strict
• round_trip

Use them carefully:

• prefer_alias=True when wire format should follow model aliases.
• validate_strict=True when Pydantic v2 coercion should be tightened.
• round_trip=True when dump behavior must preserve data for model re-validation or exact round-tripping.

Decision rules:

• Use PydanticPlugin when Pydantic behavior should be configured app-wide.
• Use PydanticInitPlugin when you want the init/serialization behavior without relying on the broader combined surface.
• Use PydanticDIPlugin when dependency constructors are Pydantic models or otherwise need plugin-assisted typed-init extraction.
• Use PydanticDTO when API contract control matters more than global plugin defaults.
• Use PydanticSchemaPlugin(prefer_alias=...) when schema generation must reflect alias choices.

Do not assume that installing PydanticPlugin removes the need for explicit DTOs. Public API contracts still need deliberate read/write shaping.

Dataclasses

Latest docs document dataclass support as DataclassDTO, not as a standalone plugin usage page.

Use:

• litestar.dto.dataclass_dto.DataclassDTO

What it provides:

• DTO field-definition generation for dataclass models.
• Nested-field detection for dataclass graphs.

Guidance:

• Prefer DataclassDTO for transport contracts.
• Do not invent a custom plugin just to support ordinary dataclass request/response models.
• If you need app-wide bootstrapping behavior around dataclass usage, that is a separate InitPlugin concern.

msgspec

Latest docs document msgspec support as MsgspecDTO, not as a standalone plugin usage page.

Use:

• litestar.dto.msgspec_dto.MsgspecDTO

What it provides:

• DTO field-definition generation for msgspec.Struct models.
• Nested-field detection for msgspec models.

Guidance:

• Prefer explicit MsgspecDTO declarations when msgspec models are the transport boundary.
• Validate wrapper responses and OpenAPI output carefully. High-performance transport types can hide contract drift if not tested.

attrs

Latest docs document attrs support as an OpenAPI schema plugin:

• litestar.plugins.attrs.AttrsSchemaPlugin
• litestar.plugins.attrs.is_attrs_class()

Guidance:

• Treat attrs support as primarily a schema-generation concern in latest Litestar docs.
• Do not assume there is a full attrs serialization plugin or attrs DTO factory in the same style as Pydantic or SQLAlchemy.
• If attrs classes are transport models in your app, verify the exact request/response and schema behavior locally before standardizing on them.

TypedDict

Latest docs do not expose a dedicated TypedDict plugin page.

Treat TypedDict support conservatively:

• Use TypedDict for static contract expression when plain annotations are sufficient.
• Verify generated OpenAPI and runtime behavior for the exact annotation shapes in play.
• If read/write transformation is required, prefer explicit DTOs or concrete transport models over assuming a TypedDict-specific plugin exists.

Implementation Rules

• Prefer the smallest plugin surface that solves the problem.
• Keep plugin order deterministic and documented.
• Prefer explicit DTOs when the API contract differs from the domain model.
• Do not mix multiple model/serialization ecosystems in one API boundary without a clear reason.
• Keep plugin behavior version-aware; latest docs differ materially from older link layouts.
• Avoid global plugin installation when handler-level DTO declarations are enough.
• Keep InitPlugin logic composition-focused; do not bury business logic in on_app_init().
• Keep ReceiveRoutePlugin side effects predictable and registration-time only.
• Keep DI plugins narrowly scoped to constructor inspection gaps.

Custom Plugin Authoring Pattern

Use a custom plugin only when built-in surfaces are insufficient.

from litestar import Litestar, get
from litestar.config.app import AppConfig
from litestar.di import Provide
from litestar.plugins import InitPlugin


@get("/health")
def healthcheck(version: str) -> dict[str, str]:
    return {"status": "ok", "version": version}


def provide_version() -> str:
    return "1.0.0"


class VersionPlugin(InitPlugin):
    def on_app_init(self, app_config: AppConfig) -> AppConfig:
        app_config.dependencies["version"] = Provide(provide_version, sync_to_thread=False)
        app_config.route_handlers.append(healthcheck)
        return app_config


app = Litestar(route_handlers=[], plugins=[VersionPlugin()])

Authoring rules:

• Implement only the protocol you need.
• Make ordering requirements explicit if the plugin must run before or after other plugins.
• Keep mutations localized and reviewable.
• Do not rely on import-time side effects.
• If the plugin generates DTOs, document when explicit dto / return_dto should override it.

Validation Checklist

• Confirm the selected surface is correct: plugin protocol vs DTO vs OpenAPI helper.
• Confirm plugin registration order is intentional and stable.
• Confirm app on_app_init hooks and plugin on_app_init() interactions are understood.
• Confirm explicit dto / return_dto declarations override plugin-generated DTO behavior where intended.
• Confirm request parsing and response serialization match the chosen model ecosystem.
• Confirm OpenAPI output is correct for Pydantic, attrs, dataclass, msgspec, and TypedDict annotations actually used.
• Confirm SQLAlchemy sync handlers are thread-safe and use sync_to_thread=True when needed.
• Confirm SQLAlchemy before_send_handler semantics match transaction boundaries.
• Confirm SQLAlchemy dependency key overrides do not break injection names.
• Confirm Piccolo and PATCH flows use partial=True plus DTOData.update_instance() when required.
• Confirm mixed serializer ecosystems are not competing at the same API boundary.
• Confirm stale docs links are not being copied into implementation decisions without checking current docs.

Cross-Skill Handoffs

• Use litestar-dto for DTO shaping, DTOConfig, wrapper handling, and custom DTO factories.
• Use litestar-databases for overall SQLAlchemy or Piccolo persistence architecture.
• Use litestar-dependency-injection when the main challenge is dependency design rather than plugin wiring.
• Use litestar-openapi when schema generation and plugin-backed OpenAPI output are the main concern.
• Use advanced-alchemy-litestar when SQLAlchemy work is really about the Advanced Alchemy integration surface.

Litestar References

Current primary references:

• https://docs.litestar.dev/latest/usage/plugins/index.html
• https://docs.litestar.dev/latest/reference/plugins/index.html
• https://docs.litestar.dev/latest/usage/databases/sqlalchemy/plugins/index.html
• https://docs.litestar.dev/latest/usage/databases/sqlalchemy/plugins/sqlalchemy_plugin.html
• https://docs.litestar.dev/latest/usage/databases/sqlalchemy/plugins/sqlalchemy_init_plugin.html
• https://docs.litestar.dev/latest/usage/databases/sqlalchemy/plugins/sqlalchemy_serialization_plugin.html
• https://docs.litestar.dev/latest/usage/databases/piccolo.html
• https://docs.litestar.dev/latest/reference/plugins/pydantic.html
• https://docs.litestar.dev/latest/reference/plugins/attrs.html
• https://docs.litestar.dev/latest/reference/dto/dataclass_dto.html
• https://docs.litestar.dev/latest/reference/dto/msgspec_dto.html