Dynamic path for upload_to in Django model (models.FileField)

Because for your task you need to use not combinations_with_replacement, but product:

import itertoolsfor i in itertools.product('0123456789', repeat=4):    print(''.join(i))

Combinations in combinatorics do not take into account the order of elements. Therefore, a set of the same elements will be considered the same combination, even if the elements are in a different order. Your code has already printed the combination of three zeros and one one (0001) once, so it will not print other variants of this combination - 0010, 0100, and 1000. The same applies to other numbers.