One shared dependency instead of a check copied into every route

Copied into every route, again.

IntermediateRead 5 minDoing: an hour, with your project open7 steps

▶ Start

What you'll have at the end

One dependency function every route needing that check now imports instead of repeating it

Before you start

You need

A running app with at least three routes that each look up the same kind of record by its path parameter and raise the same not-found error by hand if it's missing, plus some existing way to tell which account is making the call.

Not covered

Designing what your app's error responses should look like across the board; this only moves an already-working check into one shared place, it doesn't reshape what that check returns when it fails.

Leans on

7 steps

Where to go next

Split a single main.py into routers organized by domain

if the routes carrying the copied check still live together in one growing file, that recipe organizes them into per-resource packages first, which is often where the same copied check gets noticed.

Every API error looks different right now

for making the 404 and 403 this dependency raises share the same shape as every other error in your app; this recipe only stops the check itself from being copied.

Checked 18 Aug 2026

Part of the FastAPI cookbook