Django queryset filter by builderpattern

queryset_util.py

import operator
from functools import reduce

from django.db.models import Q

class QueryBuilder:
    """
    Continuous queryset filtering
    """
    
    def __init__(self, queryset):
        self.queryset = queryset

    @staticmethod
    def __get_filled_item_keys(items):
        fields = []

        for item in items:
            if item[1]:
                fields.append(item[0])

        return fields

    def conditional_filtering(self, field_name, value):
        if value:
            self.queryset = self.queryset.filter(**{field_name: value})

        return self

    def single_value_sum_filtering(self, fields, value):
        if value:
            condition = reduce(
                operator.or_,
                [Q(**{field: value}) for field in fields]
            )

            self.queryset = self.queryset.filter(condition)

        return self

    def multi_value_sum_filtering(self, **kwargs):
        fields = self.__get_filled_item_keys(kwargs.items())

        if fields.__len__() > 0:
            condition = reduce(
                operator.or_,
                [Q(**{field: kwargs[field]}) for field in fields]
            )

            self.queryset = self.queryset.filter(condition)

        return self

    def build(self):
        return self.queryset