import django_filters
#這個Q可以支持表查詢，單下劃線獲取表字段，雙下劃線獲取關聯表，
from django.db.models import Q
#引入自己的模型
from app.item.models import ItemCategory
#自定義的過濾類，需要繼承django_filter.rest_framework中的FilterSet類
class ItemCategoryFilter(django_filters.rest_framework.FilterSet):
  Filter_category = django_filters.NumberFilter(method='category_filter', label='Filter_category')
  #django_filters.NumberFilter類似，ModelForm中字段類型的控制
  #其中method指向自己定義的過濾函數，label用于標識在測試API界面中的過濾界面字段，Filter_category控制查詢字段
  def category_filter(self, queryset, name, value):
    #這里用到多級聯表查詢
    return queryset.filter(Q(category_id=value)|Q(category__parent_id=value)|Q(category__parent__parent_id=value)|Q(category__parent__parent__parent_id=value))
  class Meta:
    model = ItemCategory
    fields = []

class ItemsListByCategory(generics.ListCreateAPIView):
  '''
    根據category編號獲取相關模型no。
    請求中請帶有參數category
    @:require param: category
    such as: GET /itemsListByCategory/?Filter_category=2
  '''
  from django_filters.rest_framework import DjangoFilterBackend
  from app.item.filters import ItemCategoryFilter

  queryset = ItemCategory.objects.all()
  serializer_class = ItemCategorySerializer
  pagination_class = CommonPagination
  # 在這里哦
  filter_backends = (DjangoFilterBackend,)
  filter_class =ItemCategoryFilter
  permission_classes = (ReadOnly,)

class AlertFilter(django_filters.rest_framework.FilterSet):
  
   .......
  to_bearer_service = django_filters.rest_framework.CharFilter(method='to_bearer_service_filter', label='bearer_service')

  class Meta:
    model = Alert
    fields = [......, 'to_bearer_service']

  @staticmethod  # 如果想獲取請求信息可以去掉這個靜態方法的裝飾器，為什么要加靜態方法裝飾器我也不清楚
  def to_bearer_service_filter(queryset, name, value):
    Q_id = Q()
    for i in value.split(","):
      if i == "0":
        Q_id.add(Q(**{'to_bearer_service':None}), Q.OR)
      else:
        Q_id.add(Q(**{'to_bearer_service_id': int(i)}), Q.OR)
    queryset = queryset.filter(Q_id)
    return queryset
 
 
  def to_bearer_service_filter(self, queryset, name, value):
    Q_id = Q()
    for i in value.split(","):
      if i == "0":
        Q_id.add(Q(**{'to_bearer_service':None}), Q.OR)
      else:
        Q_id.add(Q(**{'to_bearer_service_id': int(i)}), Q.OR)
    queryset = queryset.filter(Q_id)
    return queryset