Quickstart

Define dependencies

To showcase the basics of Wirio, we will create a container able to resolve the following:

• EmailService: A simple service with no dependencies.
• UserService: A service depending on EmailService.

class EmailService:
    pass


class UserService:
    def __init__(self, email_service: EmailService) -> None:
        self.email_service = email_service

Register services

The next step is to create a container and register the dependencies we just defined.

main.py

from wirio.service_collection import ServiceCollection

services = ServiceCollection()
services.add_transient(EmailService)  # (1)!
services.add_transient(UserService)

1. Both services are registered as transient, meaning a new instance will be created each time they're requested

We'll use .add_X depending on the desired lifetime. For example: .add_transient for transient services, .add_singleton for singleton services and .add_scoped for scoped services.

Use

Finally, we convert the service collection into a service provider, which will validate and build the dependency graph, and we'll be able to request instances from it.

FastAPIConsole applicationJupyter notebook

To resolve dependencies from the service provider, we annotate the parameter with the type we want to resolve.

main.py

from wirio.annotations import FromServices

@app.post("/users")
async def create_user(
    user_service: Annotated[UserService, FromServices()],
) -> None:
    pass

services.configure_fastapi(app)  # (1)!

1. This will configure FastAPI to use Wirio's dependency injection

To resolve dependencies from the service provider, we call get_required_service with the type we want to resolve.

main.py

async with services.build_service_provider() as service_provider:
    user_service = await service_provider.get_required_service(UserService)

To resolve dependencies from the service provider, we call get_required_service with the type we want to resolve.

notebook.ipynb

service_provider = services.build_service_provider()
user_service = await service_provider.get_required_service(UserService)

Full code

FastAPIConsole applicationJupyter notebook

from typing import Annotated

from fastapi import FastAPI

from wirio.annotations import FromServices
from wirio.service_collection import ServiceCollection


class EmailService:
    pass


class UserService:
    def __init__(self, email_service: EmailService) -> None:
        self.email_service = email_service

    async def create_user(self) -> None:
        pass


app = FastAPI()


@app.post("/users")
async def create_user(
    user_service: Annotated[UserService, FromServices()],
) -> None:
    pass


services = ServiceCollection()
services.add_transient(EmailService)
services.add_transient(UserService)
services.configure_fastapi(app)

import asyncio

from wirio.service_collection import ServiceCollection

class EmailService:
    pass

class UserService:
    def __init__(self, email_service: EmailService) -> None:
        self.email_service = email_service

        async def create_user(self) -> None:
            pass


async def main() -> None:
    services = ServiceCollection()
    services.add_transient(EmailService)
    services.add_transient(UserService)

    async with services.build_service_provider() as service_provider:
        user_service = await service_provider.get_required_service(UserService)

if __name__ == "__main__":
    asyncio.run(main())

from main import services

service_provider = services.build_service_provider()
user_service = await service_provider.get_required_service(UserService)

Test

We can substitute dependencies on the fly meanwhile the context manager is active.

with service_provider.override_service(EmailService, email_service_mock):
    user_service = await service_provider.get_required_service(UserService)

For more information, check the testing documentation.