I think that from here you can remove all from the with context (at least I do not see any access to cur)
that would be awesome!
If you feel strong, refactor also the schema = dict() part, and build a list : ]
@staticmethod, those are method associated with a class and not an instance. @classmethod are use for metaprogramming, when you want to change the class definition (weird stuff).
In a…
It is OK how you write it, but I would expect root and userid as part of the __init__ constructor (give initial state).
For 4 elements a tuple is totally OK. If you expect that it will grow, use a set.
If it is a class method do not expect self as a first parameter, it is usually cls [1]
Should be done. Seems there is a bug in the UI, where here I can see both commits, but in the "Commits" tab I can see only one.