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Bake your dependencies stupidly simple!

Project description


🍰 The little DI framework that tastes like a cake. 🍰


Fresh Bakery

Fresh bakery is a lightweight [Dependency Injection][DI] framework/toolkit, which is ideal for building object dependencies in Python.

It is [nearly] production-ready, and gives you the following:

  • A lightweight, stupidly simple DI framework.
  • Fully asynchronous, no synchronous mode.
  • Any async backends compatible (asyncio, trio).
  • Zero dependencies.
  • Mypy compatible (no probably need for # type: ignore).
  • FastAPI fully compatible.
  • Pytest fully compatible (Fresh Bakery encourages the use of pytest).
  • Ease of testing.
  • Easily extended (contribution is welcome).


Python 3.6+


$ pip3 install fresh-bakery


Raw example

In this example, you can see how to create a specific IoC container using the fresh bakery library in plain python code

import asyncio

from dataclasses import dataclass
from bakery import Bakery, Cake

# your dependecies
class Settings:
    database_dsn: str
    info_id_list: list[int]

class Database:
    def __init__(self, dsn: str):
        self.dsn: str = dsn

    async def fetch_info(self, info_id: int) -> dict:
        return {"dsn": self.dsn, "info_id": info_id}

class InfoManager:
    def __init__(self, database: Database):
        self.database: Database = database

    async def fetch_full_info(self, info_id: int) -> dict:
        info: dict = await self.database.fetch_info(info_id)
        info["full"] = True
        return info

# specific ioc container, all magic happens here
class MyBakeryIOC(Bakery):
    settings: Settings = Cake(Settings, database_dsn="my_dsn", info_id_list=[1,2,3])
    database: Database = Cake(Database, dsn=settings.database_dsn)
    manager: InfoManager = Cake(InfoManager, database=database)

# code in your application that needs those dependencies ↑
async def main() -> None:
    async with MyBakery() as bakery:
        for info_id in bakery.settings.info_id_list:
            info: dict = await bakery.manager.fetch_full_info(info_id)
            assert info["dsn"] == bakery.settings.database_dsn
            assert info["info_id"] == info_id
            assert info["full"]

# just a piece of service code
if __name__ == "__main__":

FastAPI example

This is a full-fledged complex example of how you can use IoC with your FastAPI application:

import asyncio
import random
import typing

import bakery
import fastapi
import pydantic
from loguru import logger

# The following is a long and boring list of dependencies
class PersonOut(pydantic.BaseModel):
    """Person out."""

    first_name: str
    second_name: str
    age: int
    person_id: int

class FakeDbConnection:
    """Fake db connection."""

    def __init__(self, *_: typing.Any, **__: typing.Any):

class DatabaseFakeService:
    """Fake database layer."""

    def __init__(self, connection: FakeDbConnection) -> None:
        # wannabe connection only for test purposes
        self._connection: FakeDbConnection = connection

    async def __aenter__(self) -> "DatabaseFakeService":
        """On startup."""
        return self

    async def __aexit__(self, *_args: typing.Any) -> None:
        """Wannabe shutdown."""
        await asyncio.sleep(0)

    async def fetch_person(
        self, person_id: int
    ) -> dict[typing.Literal['first_name', 'second_name', 'age', 'id'], str | int]:
        """Fetch (fictitious) person."""
        return {
            'first_name': random.choice(('John', 'Danku', 'Ichigo', 'Sakura', 'Jugem', 'Ittō')),
            'second_name': random.choice(( 'Dow', 'Kurosaki', 'Amaterasu', 'Kasō', 'HiryuGekizokuShintenRaiho')),
            'age': random.randint(18, 120),
            'id': person_id,

class Settings(pydantic.BaseSettings):
    """Service settings."""

    postgres_dsn: pydantic.PostgresDsn = pydantic.Field(
    postgres_pool_min_size: int = 5
    postgres_pool_max_size: int = 20
    controller_logger_name: str = "[Controller]"

class ServiceController:
    """Service controller."""

    def __init__(
        database: DatabaseFakeService,
        logger_name: str,
        self._database = database
        self._logger_name = logger_name

    def __repr__(self) -> str:
        return self._logger_name

    async def fetch_person(self, person_id: int, /) -> PersonOut | None:
        """Fetch person by id."""
        person: typing.Mapping | None = await self._database.fetch_person(person_id)
        if not person:
            return None
        res: PersonOut = PersonOut(
        return res

def get_settings() -> Settings:
    """Get settings."""
    return Settings()

# Here is your specific IoC container
class MainBakeryIOC(bakery.Bakery):
    """Main bakery."""

    config: Settings = bakery.Cake(get_settings)
    _connection: FakeDbConnection = bakery.Cake(
    database: DatabaseFakeService = bakery.Cake(
    controller: ServiceController = bakery.Cake(

async def startup() -> None:"Init resources...")
    bakery.logger = logger
    await MainBakeryIOC.aopen()

async def shutdown() -> None:"Shutdown resources...")
    await MainBakeryIOC.aclose()

MY_APP: fastapi.FastAPI = fastapi.FastAPI(

# Finally, an example of how you can use your dependencies
async def create_person(
    inversed_controller: ServiceController = fastapi.Depends(MainBakeryIOC.controller),
) -> PersonOut | None:
    """Fetch random person from the «database»."""
    person_id: typing.Final[int] = random.randint(10**1, 10**6)
    return await inversed_controller.fetch_person(person_id)

To run this example, you will need to do the following:

  1. Install dependencies:
    pip install uvicorn fastapi loguru fresh-bakery
  2. Save the example text to the file
  3. Run uvicorn
    uvicorn test:MY_APP
  4. Open this address in the browser:
  5. And don't forget to read the logs in the console

For a more complete examples, see bakery examples.


No dependencies ;)


You can see the release history here:

Fresh Bakery is MIT licensed code.

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