File validation (size, type) in FastAPI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of file validation in FastAPI?

File validation ensures that uploaded files meet specific rules like size limits and allowed file types before processing them.

intermediate

How can you check the file size in FastAPI during upload?

You can read the file content and check its length in bytes or use the file's metadata to limit size before saving.

beginner

Which FastAPI class helps to receive uploaded files?

The UploadFile class is used to receive files uploaded by clients in FastAPI endpoints.

intermediate

How do you validate the file type in FastAPI?

Check the file's content type (MIME type) or file extension to allow only specific types like 'image/png' or '.jpg'.

beginner

What happens if a file does not meet validation rules in FastAPI?

You can raise an HTTPException with a clear error message to stop processing and inform the user about the invalid file.

Which FastAPI class is used to handle uploaded files?

A FileUpload

B UploadFile

C FileHandler

D FileInput

UploadFile is the FastAPI class designed to handle file uploads.

How can you limit the size of an uploaded file in FastAPI?

A By using a file_size decorator

B By setting a max_length parameter in UploadFile

C By checking the file size in bytes after reading the file

D FastAPI automatically limits file size

You must manually check the file size after reading it; FastAPI does not limit size automatically.

What is a common way to validate file type in FastAPI?

A Check the file's size only

B Check the file's creation date

C Check the file's owner

D Check the file's content type (MIME type)

Validating the MIME type ensures the file is of an allowed type.

What should you do if a file fails validation in FastAPI?

A Raise an HTTPException with an error message

B Ignore the file and continue

C Save the file anyway

D Restart the server

Raising an HTTPException stops processing and informs the user about the problem.

Which method reads the content of an UploadFile in FastAPI?

A read()

B open()

C load()

D fetch()

The read() method reads the file content asynchronously.

Explain how to validate both the size and type of an uploaded file in FastAPI.

Think about reading the file and checking its properties before accepting it.

Describe the steps to handle an invalid file upload in a FastAPI endpoint.

Focus on error handling and user communication.