fastapi-better-di 0.1.1

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fastapi-better-di

What is this ?

fastapi-better-di is a utility that allows you to use DI in fastapi without Depends()

Installation

pip install fastapi_better_di

Examples

# routes.py
from fastapi import APIRouter

from custom_types import MyType

api = APIRouter()


@api.get("/")
def handler(my_type: MyType):  # <- DI without Depends()
    return {"my_type": my_type.value}

# app.py
from fastapi import FastAPI
from fastapi_better_di.patcher.auto import is_pathed

from custom_types import MyType

assert is_pathed(), "Something went wrong"

app = FastAPI()

# Register types for DI
app.dependency_overrides[MyType] = lambda: MyType(123)


def register_routers():
    # Importing routers after initializing main app
    from routes import api

    app.include_router(router=api)


register_routers()

2. See full examples

Usage

You have 2 use cases:

1. Use patching:

   • Auto patching: patches classes when importing:

     from fastapi_better_di.patcher.auto import is_pathed # The classes were patched immediately after import
     
     # To check if everything is OK, use assert
     assert is_pathed(), "Something went wrong"
     

   • Manual patching: you need to call patch() by yourself:

     from fastapi_better_di.patcher.manual import patch, is_pathed
     
     patch()
     
     # To check if everything is OK, use assert
     assert is_pathed(), "Something went wrong"
     

   • Patching example

2. Use DI Classes: FastAPIDI, APIRouterDI, APIRouteDI
   • Use FastAPIDI instead of FastAPI
   • Use APIRouterDI instead of APIRouter
   • Use APIRouteDI instead of APIRoute
   • DI Classes example

• IMPORTANT: You can still use = Depends() without a function as an argument, and it won't add unnecessary arguments to the swagger.

  • Related issue: fastapi issue

• IMPORTANT: The main app(FastAPIDI) and dependency_overrides must be initialized before importing routers!

How it works

fastapi-better-di simply patch the handler function and add = Depends(func) as the default argument