@register.filter def leading_zeros(value, desired_digits): """ Given an integer, returns a string representation, padded with [desired_digits] zeros. """ num_zeros = int(desired_digits) - len(str(value)) padded_value = [] while num_zeros >= 1: padded_value.append("0") num_zeros = num_zeros - 1 padded_value.append(str(value)) return "".join(padded_value)