Router prefix and tags in FastAPI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of a prefix in a FastAPI router?

The prefix adds a common path to all routes in the router, so you don't have to repeat it for each route. It helps organize routes under a shared URL segment.

beginner

How do tags help when using routers in FastAPI?

tags group routes in the automatic API docs, making it easier to find and understand related endpoints.

beginner

Show an example of creating a FastAPI router with a prefix /items and tag Items.

from fastapi import APIRouter

router = APIRouter(prefix="/items", tags=["Items"])

@router.get("/")
async def read_items():
    return [{"item_id": "foo"}]

intermediate

What happens if you add a prefix to a router and then include it in the main FastAPI app?

All routes in that router will have the prefix added to their paths automatically when included in the main app.

beginner

Can you assign multiple tags to a FastAPI router? How?

Yes, by passing a list of strings to the tags parameter, e.g., tags=["Users", "Admin"].

What does the prefix parameter do in a FastAPI router?

A Changes the HTTP method of routes

B Groups routes in the API docs

C Adds a common path to all routes in the router

D Defines the response model for routes

The prefix adds a shared path segment to all routes in the router.

How do tags affect FastAPI routes?

A They define middleware for routes

B They change the URL path of routes

C They set the HTTP status code

D They group routes in the API documentation

Tags group routes in the automatic API docs for better organization.

If a router has prefix /users and a route @router.get("/profile"), what is the full path?

A /users/profile

B /profile/users

C /users

D /profile

The prefix is added before the route path, so the full path is /users/profile.

Which of these is a valid way to assign multiple tags to a FastAPI router?

A tags="Users,Admin"

B tags=["Users", "Admin"]

C tags=(Users, Admin)

D tags={Users, Admin}

Tags must be a list of strings, like ["Users", "Admin"].

Where do you define the prefix and tags for a group of routes in FastAPI?

A When creating the APIRouter instance

B Inside each route function

C In the main FastAPI app only

D In the response model

Prefix and tags are set when creating the APIRouter instance.

Explain how router prefixes and tags help organize routes in a FastAPI application.

Think about URL paths and API documentation.

Describe how you would create a router with prefix '/products' and tags ['Products', 'Store'] in FastAPI.

Focus on APIRouter parameters.