FastAPI Utils

0.8.0 · active · verified Sun Apr 12

FastAPI Utils is a Python library providing reusable utilities for FastAPI applications, including class-based views, repeated tasks, timing middleware, and SQLAlchemy session management. It is currently at version 0.8.0 and releases seem to be quarterly or bi-annually based on recent GitHub activity.

Warnings

deprecated The `InferringRouter` class was deprecated in `fastapi-utils` v0.4.4. Its core functionality for inferring response models is now a built-in feature of `fastapi.APIRouter` in recent FastAPI versions.
Fix: Replace `from fastapi_utils.inferring_router import InferringRouter` with `from fastapi import APIRouter` and use it directly.
gotcha When using `@cbv` (Class-Based Views), any dependencies defined as class attributes will be resolved and injected for *every* endpoint method within that class, even if a specific method doesn't explicitly use `self.dependency_name`. This can lead to unnecessary work if dependencies are expensive and not universally required.
Fix: Structure your CBV classes to group endpoints with genuinely shared dependencies, or move non-universally required dependencies to the method signature of specific endpoints.
gotcha For `repeat_every` background tasks, if you're using a modern FastAPI version (0.68.0+), `app.on_event("startup")` is deprecated in favor of `asynccontextmanager` for managing application lifespan.
Fix: Adapt your application to use `asynccontextmanager` for lifespan events and call your `repeat_every` decorated functions within the `startup` block of the lifespan context. Refer to FastAPI's official documentation on lifespan events.
breaking fastapi-utils v0.4.0 introduced a breaking change by removing support for Python versions < 3.6.2. Ensure your project runs on Python 3.8+ as per current requirements.
Fix: Upgrade your Python environment to 3.8 or newer. The current version (0.8.0) requires Python >=3.8.

Install

pip install fastapi-utils Basic Install
pip install fastapi-utils[session] With SQLAlchemy Session Maker

Imports

cbv
```
from fastapi_utils.cbv import cbv
```
InferringRouter
```
from fastapi.routing import APIRouter
```
InferringRouter was deprecated in v0.4.4 as its functionality was integrated into FastAPI's native APIRouter.

repeat_every

from fastapi_utils.tasks import repeat_every

FastAPISessionMaker

from fastapi_utils.session import FastAPISessionMaker

APIModel

from fastapi_utils.api_model import APIModel

APISettings

from fastapi_utils.settings import APISettings

StrEnum
```
from fastapi_utils.enums import StrEnum
```

CamelStrEnum

from fastapi_utils.enums import CamelStrEnum

GUID

from fastapi_utils.guid_type import GUID

Quickstart

This quickstart demonstrates the use of Class-Based Views (CBV) to group related endpoints and share dependencies, a core feature of fastapi-utils. Methods within the `@cbv` decorated class become endpoints on the included router, and class-level `Depends` declarations are injected as instance attributes.

from fastapi import FastAPI, Depends, APIRouter
from fastapi_utils.cbv import cbv
from fastapi_utils.inferring_router import InferringRouter # Still commonly seen, but prefer APIRouter

app = FastAPI()
router = InferringRouter() # Or APIRouter() for newer FastAPI versions

def common_dependency():
    return "Shared Data"

@cbv(router)
class ClassBasedView:
    # Dependencies shared by all methods in this class
    shared_data: str = Depends(common_dependency)

    @router.get("/items/")
    def read_items(self):
        return {"message": f"Hello from CBV, shared data: {self.shared_data}"}

    @router.post("/items/")
    def create_item(self, item_name: str):
        return {"message": f"Item '{item_name}' created with shared data: {self.shared_data}"}

app.include_router(router)

# To run: uvicorn main:app --reload (assuming this code is in main.py)

view raw JSON →