I’m trying to use a custom type of filter like BoundFilter in aiogram 2.x for filtering not allowed characters.

But recommended

class AllowedCharactersFilter(BoundFilter):
    async def check(self, message: types.Message):
        allowed_characters = set('abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890')
        entered_text = message.text
        return all(char in allowed_characters for char in entered_text)

doesn’t work. Because in aiogram 3.4 neither

from aiogram.dispather.filters import BoundFilter

nor

from aiogram.filters import BoundFilter

work.

Is BoundFilter to be imported in some another fashion?

I found that probably the solution is possible through using a BaseFilter imported from aiogram.filters. With creation of new directory under filters.

But a description of the procedure is not clear. Can comebody shed a light on the subject: How to filter unallowed characters in handlers of aiogram 3.4?