Available fields in hooks?

I'm trying to create a generic hook for setting a default value on a field on save, but whenever someone saves the document, the field key is not there when the field has not been filled in by the user.

Would it possible to to get the available fields for a collection while in a hook?

Well, I think I answered my own question. For future reference:

You can get the

object in a hook, which includes a

key

So you can access the configured fields like this: