Filter by dynamic schema

[nazarlitvin]

Hi, in my application, I use before_marshmallow to set the schema based on a user type, in overall it works well, but I faced a few difficulties:

1. I have to provide a default schema and only then override it. Otherwise, it doesn't work. Like this:

schema = BaseSchema

def before_marshmallow(self, args, kwargs):
  if (kwargs["user_type"] == "A"):
    self.schema = SchemaA
  elif (kwargs["user_type"] == "B"):
    self.schema = SchemaB

But, again, on overall it's OK.

2. Much important issue is with filtering. With my approach, I'm only able to filter by fields from BaseSchema. Is there any workaround?