fastapi-class-router 0.1.1

FastApi_Class_Router is a lightweight yet powerful library for implementing class-based routing in FastAPI. It allows you to organise your API’s logic into classes, which significantly improves code structure, promotes component reusability and facilitates the implementation of dependency injection.

fastapi-class-router

CBV-style (class-based views) controller wrapper for FastAPI that preserves 100% of APIRouter functionality.

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Features

• @get, @post, @put, @delete, @patch decorators directly on class methods
• __init__ dependencies resolved per-request via FastAPI's Depends — shared across all routes in the controller
• Full APIRouter compatibility: prefix, tags, dependencies, responses
• Route inheritance — child controllers inherit routes from parent classes
• as_router() and attach_to() for flexible integration
• Sync and async endpoints both supported
• OpenAPI schema passthrough: summary, description, deprecated, operation_id, include_in_schema

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Installation

pip install fastapi-class-router

Requires Python ≥ 3.10 and FastAPI ≥ 0.100.

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Quick Start

from fastapi import FastAPI, Depends
from fastapi_class_router import ClassRouter, get, post, put, delete

app = FastAPI()

# ── Dependencies ──────────────────────────────────────────────────────────────

def get_db():
    return {"connected": True}   # replace with a real session

# ── Schema ────────────────────────────────────────────────────────────────────

from pydantic import BaseModel

class ItemOut(BaseModel):
    id: int
    name: str

class ItemCreate(BaseModel):
    name: str

# ── Controller ────────────────────────────────────────────────────────────────

class ItemController(ClassRouter, prefix="/items", tags=["Items"]):
    """
    All dependencies declared in __init__ are injected per-request by FastAPI.
    No manual Depends() wiring needed on individual methods.
    """

    def __init__(self, db=Depends(get_db)):
        self.db = db

    @get("/", response_model=list[ItemOut])
    async def list_items(self):
        return []

    @post("/", response_model=ItemOut, status_code=201)
    async def create_item(self, body: ItemCreate):
        return {"id": 1, "name": body.name}

# ── Register ──────────────────────────────────────────────────────────────────

app.include_router(ItemController.as_router())

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Class kwargs

kwarg	Type	Description
prefix	str	URL prefix applied to all routes
tags	list[str]	OpenAPI tags for all routes
dependencies	list	Depends(...) applied to every route in the class
responses	dict	Shared response definitions

class SecureController(
    ClassRouter,
    prefix="/admin",
    tags=["Admin"],
    dependencies=[Depends(require_admin)],
    responses={403: {"description": "Forbidden"}},
):
    ...

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Route decorators

All decorators accept the same kwargs as APIRouter.add_api_route:

@get(
    "/",
    response_model=list[ItemOut],
    status_code=200,
    summary="List all items",
    description="Returns a paginated list of items.",
    deprecated=False,
    operation_id="list_items",
    include_in_schema=True,
    dependencies=[Depends(log_request)],
    responses={429: {"description": "Rate limited"}},
)
async def list_items(self):
    ...

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Dependency Injection

Controller-level (shared across all routes)

class ReportController(ClassRouter, prefix="/reports"):
    def __init__(
        self,
        db: Session = Depends(get_db),
        current_user: User = Depends(get_current_user),
    ):
        self.db = db
        self.current_user = current_user

    @get("/")
    async def list_reports(self):
        # self.db and self.current_user are available here
        ...

Route-level (specific to one endpoint)

@get("/export")
async def export(self, fmt: str = Depends(parse_format)):
    ...

Both levels can be combined freely.

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Registration options

Option 1 — directly on the app

app.include_router(ItemController.as_router())

Option 2 — attach to an existing router (versioning)

from fastapi import APIRouter

v1 = APIRouter(prefix="/api/v1")
ItemController.attach_to(v1)
UserController.attach_to(v1)

app.include_router(v1)

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Inheritance

Child controllers automatically inherit routes from their parents. Overriding a route is as simple as redefining the method:

class BaseController(ClassRouter, prefix="/base"):
    def __init__(self): pass

    @get("/hello")
    async def hello(self):
        return {"msg": "from base"}


class ChildController(BaseController, prefix="/child"):
    @get("/hello")          # overrides the parent route
    async def hello(self):
        return {"msg": "from child"}

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