FastIoC

IoC/DI container for FastAPI with automatic type-based dependency injection

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Why FastIoC 🤔

FastIoC bridges the gap between Python’s dynamic nature and modern dependency injection patterns found in frameworks like .NET, Laravel, Spring Boot, and NestJS — with zero boilerplate and full FastAPI compatibility.

Features:

• 🧹 Write cleaner, loosely coupled code while staying true to the ⛓️‍💥 Dependency Inversion Principle (SOLID - D) — with ABSOLUTELY ZERO boilerplate! ⚡

• ⚙️ Enjoy hassle-free, automatic nested dependency resolution using Python type hints with flexible lifetimes: ♻️ Singleton, 🧺 Scoped, and ♨️ Transient (inspired by .NET)

• 🚀 Zero runtime overhead — everything is resolved at startup!

• 🤝 100% compatible & based on FastAPI’s native dependency injection — no black boxes, no magic 🪄

• ♻️ Singleton support with automatic cleanup on application shutdown 🧹

• 🧪 Full support for FastAPI's dependency_overrides using type annotations — even with mock containers 💉

• 📦 Comes with the amazing APIController — the best class-based view (CBV) system ever seen in Python 🏆

• 🔄 Two operation modes: standalone 🏕️ and integrated 🧩

• 🔧 Comes with customizable hooks, detailed logs & ... 📊

Installation 📥

$ pip install fastioc

Usage 💡

A sample interface & implementation:

from typing import Protocol

# Define the interface 📜
class IService(Protocol):

    def get_number(self) -> int: ...


# Implement concrete class 🏗️
class ExampleService(IService):

    def __init__(self):
        print("ExampleService created")
        self.number = 42

    def get_number(self) -> int:
        return self.number

Standalone Mode 🏕️

from fastapi import FastAPI

from fastioc import Container # Import the Container


# Create container and register dependency 📝
container = Container()
container.add_scoped(IService, ExampleService) # Also available: add_singleton, add_transient


# Create FastAPI app and integrate it with the container 🪄
app = FastAPI()
container.injectify(app)


# Now your endpoints are injectified! 🎉
@app.get('/')
def index(service: IService) -> int: # Only use the interface - no 'Depends' needed
    return service.get_number() # 42 🤩

APIController 📦

from fastapi import FastAPI

from fastioc import Container
from fastioc.controller import APIController, get, post

# Create container & register dependencies 📝
container = Container()
container.add_scoped(IService, ExampleService)

# Define an example controller
class ExampleController(APIController):
    config = { # APIRouter parameters (+ IDE Autocomplete 🤩)
        "prefix": '/example',
        "tag": 'example',
        "container": container # ! DO NOT FORGET
    }

    service: IService # Available in all endpoints!

    @get('/read')
    def read_example(self) -> int:
        return self.service.get_number()

    @post('/set')
    def set_example(self) -> bool:
        self.service.number = 24
        return True

app = FastAPI()
app.include_router(ExampleController.router()) # Get router from controller and include it

• APIController endpoints are injectified so you can also resolve dependencies in each endpoint separately.
• You can also resolve dependencies in __init__ of your controller.
• Read more in the APIController documentation

Learn More 📘

Check out the 📄 full documentation for advanced examples, architecture guides, best practices, and more.

Contributing 💬

Got an idea, found a bug, or want to improve FastIoC?
Feel free to open an issue or submit a pull request — contributions are always welcome 🤝

License ⚖️

This project is licensed under the MIT License — see the LICENSE file for details.