Another agg ES response strategy

apps/search_indexes/filters.py

@@ -1,7 +1,48 @@
 """Search indexes filters."""
 from elasticsearch_dsl.query import Q
-from django_elasticsearch_dsl_drf.filter_backends import SearchFilterBackend
+from django_elasticsearch_dsl_drf.filter_backends import SearchFilterBackend, FacetedSearchFilterBackend
 from search_indexes.utils import OBJECT_FIELD_PROPERTIES
+from six import iteritems
+
+
+class CustomFacetedSearchFilterBackend(FacetedSearchFilterBackend):
+
+    def __init__(self):
+        self.facets_computed = {}
+
+    def aggregate(self, request, queryset, view):
+        """Aggregate.
+
+        :param request:
+        :param queryset:
+        :param view:
+        :return:
+        """
+        def makefilter(cur_facet):
+           def myfilter(x):
+               return cur_facet['facet']._params['field'] != next(iter(x._params))
+           return myfilter
+        __facets = self.construct_facets(request, view)
+        for __field, __facet in iteritems(__facets):
+            agg = __facet['facet'].get_aggregation()
+            agg_filter = Q('match_all')
+            if __facet['global']:
+                queryset.aggs.bucket(
+                    '_filter_' + __field,
+                    'global'
+                ).bucket(__field, agg)
+            else:
+                qs = queryset._clone()
+                filterer = makefilter(__facet)
+                qs.query._proxied._params['must'] = list(filter(filterer, qs.query._proxied._params['must']))
+                facet_name = '_filter_' + __field
+                qs.aggs.bucket(
+                    facet_name,
+                    'filter',
+                    filter=agg_filter
+               ).bucket(__field, agg)
+                self.facets_computed.update({facet_name: qs.execute().aggregations[facet_name]})
+        return queryset
 
 
 class CustomSearchFilterBackend(SearchFilterBackend):

apps/search_indexes/views.py

@@ -14,7 +14,25 @@ from search_indexes.documents.product import ProductDocument
 from utils.pagination import ESDocumentPagination
 
 
-class NewsDocumentViewSet(BaseDocumentViewSet):
+class FacetedResponseMixin:
+    def filter_queryset(self, queryset):
+        """
+        Given a queryset, filter it with whichever filter backend is in use.
+
+        You are unlikely to want to override this method, although you may need
+        to call it either from a list view, or from a custom `get_object`
+        method if you want to apply the configured filtering backend to the
+        default queryset.
+        """
+        for backend in list(self.filter_backends):
+            bc = backend()
+            queryset = bc.filter_queryset(self.request, queryset, self)
+            if hasattr(bc, 'facets_computed'):
+                setattr(self, 'facets_computed', bc.facets_computed)
+        return queryset
+
+
+class NewsDocumentViewSet(BaseDocumentViewSet, FacetedResponseMixin):
     """News document ViewSet."""
 
     document = NewsDocument
@@ -26,7 +44,7 @@ class NewsDocumentViewSet(BaseDocumentViewSet):
     filter_backends = [
         filters.CustomSearchFilterBackend,
         FilteringFilterBackend,
-        FacetedSearchFilterBackend,
+        filters.CustomFacetedSearchFilterBackend,
     ]
 
     faceted_search_fields = {
@@ -86,7 +104,7 @@ class MobileNewsDocumentViewSet(NewsDocumentViewSet):
     ]
 
 
-class EstablishmentDocumentViewSet(BaseDocumentViewSet):
+class EstablishmentDocumentViewSet(BaseDocumentViewSet, FacetedResponseMixin):
     """Establishment document ViewSet."""
 
     document = EstablishmentDocument
@@ -103,7 +121,7 @@ class EstablishmentDocumentViewSet(BaseDocumentViewSet):
         FilteringFilterBackend,
         filters.CustomSearchFilterBackend,
         GeoSpatialFilteringFilterBackend,
-        FacetedSearchFilterBackend,
+        filters.CustomFacetedSearchFilterBackend,
     ]
 
     faceted_search_fields = {
@@ -306,7 +324,7 @@ class ProductDocumentViewSet(BaseDocumentViewSet):
     filter_backends = [
         FilteringFilterBackend,
         filters.CustomSearchFilterBackend,
-        FacetedSearchFilterBackend,
+        filters.CustomFacetedSearchFilterBackend,
     ]
 
     search_fields = {

apps/utils/pagination.py

@@ -6,7 +6,6 @@ from django.conf import settings
 from rest_framework.pagination import CursorPagination, PageNumberPagination
 from django_elasticsearch_dsl_drf.pagination import PageNumberPagination as ESPagination
 
-
 class ProjectPageNumberPagination(PageNumberPagination):
     """Customized pagination class."""
 
@@ -65,6 +64,23 @@ class ESDocumentPagination(ESPagination):
             return None
         return self.page.previous_page_number()
 
+    def get_facets(self, page=None):
+        """Get facets.
+
+        :param page:
+        :return:
+        """
+        if page is None:
+            page = self.page
+
+        if hasattr(self, 'facets_computed'):
+            ret = {}
+            for filter_field, bucket_data in self.facets_computed.items():
+                ret.update({filter_field: bucket_data.__dict__['_d_']})
+            return ret
+        elif hasattr(page, 'facets') and hasattr(page.facets, '_d_'):
+            return page.facets._d_
+
 
 class EstablishmentPortionPagination(ProjectMobilePagination):
     """