HTTPException usage in FastAPI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is HTTPException used for in FastAPI?

HTTPException is used to send HTTP error responses from your API. It stops normal processing and returns an error status code and message to the client.

beginner

How do you raise a 404 error using HTTPException in FastAPI?

You use raise HTTPException(status_code=404, detail='Item not found') inside your path operation function.

beginner

What parameters does HTTPException accept?

HTTPException mainly accepts status_code (an integer like 404 or 400) and detail (a message explaining the error).

beginner

What happens when you raise HTTPException in a FastAPI route?

The request stops processing, and FastAPI sends an HTTP response with the given status code and detail message to the client.

intermediate

Can you customize the response headers when raising HTTPException?

Yes, you can pass a headers dictionary to HTTPException to add custom HTTP headers in the error response.

Which of these is the correct way to raise a 400 Bad Request error in FastAPI?

A return Response(status_code=400)

B return HTTPException(400, 'Bad request')

C raise Exception('400 Bad Request')

D raise HTTPException(status_code=400, detail='Bad request')

Only raise HTTPException(status_code=400, detail='Bad request') correctly raises the HTTP error in FastAPI.

What does the detail parameter in HTTPException do?

A Provides a message explaining the error

B Sets the HTTP status code

C Defines the response headers

D Specifies the request method

detail is used to give a clear message about the error to the client.

If you want to add a custom header to an error response, which HTTPException parameter do you use?

A headers

B status_code

C detail

D content

The headers parameter lets you add custom HTTP headers to the error response.

What happens after you raise HTTPException in a FastAPI route?

A The route continues running

B FastAPI sends the error response immediately

C The server crashes

D Nothing happens

Raising HTTPException stops the route and sends the error response to the client.

Which status code is commonly used with HTTPException to indicate 'Not Found'?

A 200

B 500

C 404

D 302

404 means the requested resource was not found.

Explain how to use HTTPException in a FastAPI route to handle errors.

Think about how you stop normal processing and tell the client about an error.

Describe how you can customize the error response when raising HTTPException.

Consider what extra info you can send besides status and message.