litestar 2.17.0

Litestar - A production-ready, highly performant, extensible ASGI API Framework

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Litestar is a powerful, flexible yet opinionated ASGI framework, focused on building APIs. It offers high-performance data validation, dependency injection, first-class ORM integration, authorization primitives, a rich plugin API, middleware, and much more that's needed to get applications up and running.

Check out the documentation 📚 for a detailed overview of its features!

Additionally, the Litestar fullstack repository can give you a good impression how a fully fledged Litestar application may look.

Table of Contents

• Installation
  • Quick Start
• Core Features
  • Example Applications
• Features
  • Class-based Controllers
  • Data Parsing, Type Hints, and Msgspec
  • Plugin System, ORM support, and DTOs
  • OpenAPI
  • Dependency Injection
  • Middleware
  • Route Guards
  • Request Life Cycle Hooks
• Performance
• Contributing

Installation

pip install litestar

or to include the CLI and a server (uvicorn) for running your application:

pip install 'litestar[standard]'

Quick Start

from litestar import Litestar, get

@get("/")
async def hello_world() -> dict[str, str]:
    """Keeping the tradition alive with hello world."""
    return {"hello": "world"}

app = Litestar(route_handlers=[hello_world])

And run it with

litestar run

Core Features

• Class based controllers
• Dependency Injection
• Layered Middleware
• Plugin System
• OpenAPI 3.1 schema generation
• Life Cycle Hooks
• Route Guards based Authorization
• Support for dataclasses, TypedDict, msgspec, pydantic version 1 and version 2 (even within the same application) and (c)attrs msgspec and attrs
• Layered parameter declaration
• Support for RFC 9457 standardized "Problem Detail" error responses
• Automatic API documentation with:
  • Scalar
  • RapiDoc
  • Redoc
  • Stoplight Elements
  • Swagger-UI
• Trio support (built-in, via AnyIO)
• Ultra-fast validation, serialization and deserialization using msgspec
• SQLAlchemy integration

Example Applications

Pre-built Example Apps

• litestar-hello-world: A bare-minimum application setup. Great for testing and POC work.
• litestar-fullstack: A reference application that contains most of the boilerplate required for a web application. It features a Litestar app configured with best practices, SQLAlchemy 2.0 and SAQ, a frontend integrated with Vitejs and Jinja2 templates, Docker, and more. Like all Litestar projects, this application is open to contributions, big and small.

Sponsors

Litestar is an open-source project, and we enjoy the support of our sponsors to help fund the exciting work we do.

A huge thanks to our sponsors:

Check out our sponsors in the docs

If you would like to support the work that we do please consider becoming a sponsor via Polar.sh (preferred), GitHub or Open Collective.

Also, exclusively with Polar, you can engage in pledge-based sponsorships.

Features

Class-based Controllers

While supporting function-based route handlers, Litestar also supports and promotes python OOP using class based controllers:

Example for class-based controllers

from typing import List, Optional
from datetime import datetime

from litestar import Controller, get, post, put, patch, delete
from litestar.dto import DTOData
from pydantic import UUID4

from my_app.models import User, PartialUserDTO


class UserController(Controller):
    path = "/users"

    @post()
    async def create_user(self, data: User) -> User: ...

    @get()
    async def list_users(self) -> List[User]: ...

    @get(path="/{date:int}")
    async def list_new_users(self, date: datetime) -> List[User]: ...

    @patch(path="/{user_id:uuid}", dto=PartialUserDTO)
    async def partial_update_user(
        self, user_id: UUID4, data: DTOData[PartialUserDTO]
    ) -> User: ...

    @put(path="/{user_id:uuid}")
    async def update_user(self, user_id: UUID4, data: User) -> User: ...

    @get(path="/{user_name:str}")
    async def get_user_by_name(self, user_name: str) -> Optional[User]: ...

    @get(path="/{user_id:uuid}")
    async def get_user(self, user_id: UUID4) -> User: ...

    @delete(path="/{user_id:uuid}")
    async def delete_user(self, user_id: UUID4) -> None: ...

Data Parsing, Type Hints, and Msgspec

Litestar is rigorously typed, and it enforces typing. For example, if you forget to type a return value for a route handler, an exception will be raised. The reason for this is that Litestar uses typing data to generate OpenAPI specs, as well as to validate and parse data. Thus, typing is essential to the framework.

Furthermore, Litestar allows extending its support using plugins.

Plugin System, ORM support, and DTOs

Litestar has a plugin system that allows the user to extend serialization/deserialization, OpenAPI generation, and other features.

It ships with a builtin plugin for SQL Alchemy, which allows the user to use SQLAlchemy declarative classes "natively" i.e., as type parameters that will be serialized/deserialized and to return them as values from route handlers.

Litestar also supports the programmatic creation of DTOs with a DTOFactory class, which also supports the use of plugins.

OpenAPI

Litestar has custom logic to generate OpenAPI 3.1.0 schema, include optional generation of examples using the polyfactory library.

ReDoc, Swagger-UI and Stoplight Elements API Documentation

Litestar serves the documentation from the generated OpenAPI schema with:

• ReDoc
• Swagger-UI
• Stoplight Elements
• RapiDoc

All these are available and enabled by default.

Dependency Injection

Litestar has a simple but powerful DI system inspired by pytest. You can define named dependencies - sync or async - at different levels of the application, and then selective use or overwrite them.

Example for DI

from litestar import Litestar, get
from litestar.di import Provide


async def my_dependency() -> str: ...


@get("/")
async def index(injected: str) -> str:
    return injected


app = Litestar([index], dependencies={"injected": Provide(my_dependency)})

Middleware

Litestar supports typical ASGI middleware and ships with middlewares to handle things such as

• CORS
• CSRF
• Rate limiting
• GZip and Brotli compression
• Client- and server-side sessions

Route Guards

Litestar has an authorization mechanism called guards, which allows the user to define guard functions at different level of the application (app, router, controller etc.) and validate the request before hitting the route handler function.

Example for route guards

from litestar import Litestar, get

from litestar.connection import ASGIConnection
from litestar.handlers.base import BaseRouteHandler
from litestar.exceptions import NotAuthorizedException


async def is_authorized(connection: ASGIConnection, handler: BaseRouteHandler) -> None:
    # validate authorization
    # if not authorized, raise NotAuthorizedException
    raise NotAuthorizedException()


@get("/", guards=[is_authorized])
async def index() -> None: ...


app = Litestar([index])

Request Life Cycle Hooks

Litestar supports request life cycle hooks, similarly to Flask - i.e. before_request and after_request

Performance

Litestar is fast. It is on par with, or significantly faster than comparable ASGI frameworks.

You can see and run the benchmarks here, or read more about it here in our documentation.

Contributing

Litestar is open to contributions big and small. You can always join our discord server or join our Matrix space to discuss contributions and project maintenance. For guidelines on how to contribute, please see the contribution guide.