Only accept a certain file type in FileField, server-side

Question

How can I restrict FileField to only accept a certain type of file (video, audio, pdf, etc.) in an elegant way, server-side?

Answer 1

after I checked the accepted answer, I decided to share a tip based on Django documentation. There is already a validator for use to validate file extension. You don't need to rewrite your own custom function to validate whether your file extension is allowed or not.

https://docs.djangoproject.com/en/3.0/ref/validators/#fileextensionvalidator

Warning

Don’t rely on validation of the file extension to determine a file’s type. Files can be renamed to have any extension no matter what data they contain.