You want to create a dependency that extracts a user ID from a header and then fetches the user from the database. How should you combine these dependencies in FastAPI?

hard🚀 Application Q8 of 15

FastAPI - Dependency Injection

AUse nested Depends: one dependency calls another inside its function.

BDeclare both dependencies separately in the path operation parameters.

CUse a single dependency that accepts both header and database parameters.

DUse Depends only on the database fetch function, ignoring the header.

Step-by-Step Solution

Solution:

Step 1: Understand dependency chaining
In FastAPI, one dependency can call another by using Depends inside its function parameters.
Step 2: Apply nested Depends for header and database fetch
The header extraction dependency can be called inside the database fetch dependency to chain them.
Final Answer:
Use nested Depends: one dependency calls another inside its function. -> Option A
Quick Check:
Nested Depends enable chaining dependencies [OK]

Quick Trick: Chain dependencies by calling Depends inside dependency functions [OK]

Common Mistakes:

MISTAKES

Declaring dependencies separately without chaining
Ignoring header extraction dependency
Trying to combine unrelated parameters in one function

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More FastAPI Quizzes

You want to create a dependency that extracts a user ID from a header and then fetches the user from the database. How should you combine these dependencies in FastAPI?

Step 1: Understand dependency chaining

Step 2: Apply nested Depends for header and database fetch

Final Answer:

Quick Check:

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