Fastpi Depends Stub

README.md

This Stub class is designed as a workaround for Fastapi Depends which mixes IoC-Container features with request parsing.

You can use parametrized Stub instance to declare dependency whilst not show your class'es __init__ params in OpenAPI specification.

app.py

from fastapi import FastAPI, APIRouter, Depends

from stub import Stub

app = FastAPI()
router = APIRouter()


class Repo:
    def __init__(self, a: int):
        self.a = a


@app.get("/")
async def root(repo: Repo = Depends(Stub(Repo))) -> int:
    return repo.a


@app.get("/1")
async def root(repo: Repo = Depends(Stub(Repo, key="1"))) -> int:
    return repo.a


app.dependency_overrides[Repo] = lambda: Repo(0)
app.dependency_overrides[Stub(Repo, key="1")] = lambda: Repo(1)

stub.py

from typing import Callable


class Stub:
    def __init__(self, dependency: Callable, **kwargs):
        self._dependency = dependency
        self._kwargs = kwargs

    def __call__(self):
        raise NotImplementedError

    def __eq__(self, other) -> bool:
        if isinstance(other, Stub):
            return (
                    self._dependency == other._dependency
                    and self._kwargs == other._kwargs
            )
        else:
            if not self._kwargs:
                return self._dependency == other
            return False

    def __hash__(self):
        if not self._kwargs:
            return hash(self._dependency)
        serial = (
            self._dependency,
            *self._kwargs.items(),
        )
        return hash(serial)