from pony.orm import *

db = Database()


class Product(db.Entity):
    id = PrimaryKey(int, auto=True)
    name = Required(str)
    stars = Optional(IntArray)
    tags = Optional(StrArray)


db.bind('sqlite', ':memory:')
db.generate_mapping(create_tables=True)

with db_session:
    product = Product(name='abc', stars=[1, 2, 3], tags = ['qwe'])
    tags = select(p.stars[:3] for p in Product)[:]#ok
    print(tags)
    end = 3
    tags = select(p.stars[:end] for p in Product)[:]#TypeError: Array indices should be type of int