Shared dependencies across routers in FastAPI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a shared dependency in FastAPI routers?

A shared dependency is a function or class that multiple routers use to provide common data or logic, like authentication or database access, so you don't repeat code.

beginner

How do you apply a shared dependency to multiple routers in FastAPI?

You add the dependency to each router using the 'dependencies' parameter when creating the router, so all routes inside use it automatically.

intermediate

Why use shared dependencies across routers instead of repeating them in each route?

It keeps code clean and consistent, makes maintenance easier, and ensures all routes share the same logic like security checks or database sessions.

intermediate

Show a simple example of a shared dependency function used in two routers.

Example: Define a function 'get_current_user' that checks user info. Add it as a dependency in two routers with 'dependencies=[Depends(get_current_user)]'. Both routers then require the user info.

advanced

Can shared dependencies in FastAPI routers have parameters or state?

Yes, dependencies can accept parameters or use classes with state. FastAPI handles calling them and injecting needed values automatically.

What parameter do you use to add shared dependencies to a FastAPI router?

A dependencies

B shared

C include

D inject

The 'dependencies' parameter is used to add shared dependencies to a router.

Why is it better to use shared dependencies across routers?

A To repeat code in every route

B To avoid using dependencies

C To keep code clean and consistent

D To slow down the app

Shared dependencies keep code clean and consistent by avoiding repetition.

Which FastAPI function helps inject dependencies into routes?

A Depends

B Inject

C Provide

D Use

'Depends' is the FastAPI function used to declare dependencies.

Can shared dependencies in FastAPI routers handle authentication?

A No, dependencies are only for data

B No, only for database

C Only for logging

D Yes, they can handle authentication

Shared dependencies can handle authentication logic for routers.

If you want all routes in a router to require a user check, where do you add the dependency?

A In each route decorator

B In the router's dependencies list

C In the main app only

D In the database connection

Adding the dependency to the router's dependencies list applies it to all routes inside.

Explain how to share a dependency function across multiple FastAPI routers and why this is useful.

Think about common tasks like authentication or database access.

Describe a scenario where shared dependencies in FastAPI routers improve your app's structure and maintenance.

Consider security checks or user info retrieval.