Added view for nearest establishments

apps/establishment/models.py

@@ -102,6 +102,20 @@ class EstablishmentQuerySet(models.QuerySet):
             default=False,
             output_field=models.BooleanField(default=False)))
 
+    def by_distance_from_point(self, center, radius, unit='m'):
+        """
+        Returns nearest establishments
+
+        :param center: point from which to find nearby establishments
+        :param radius: the maximum distance within the radius of which to look for establishments
+        :return: all establishments within the specified radius of specified point
+        :param unit: length unit e.g. m, km. Default is 'm'.
+        """
+
+        from django.contrib.gis.measure import Distance
+        kwargs = {unit: radius}
+        return self.filter(address__coordinates__distance_lte=(center, Distance(**kwargs)))
+
 
 class Establishment(ProjectBaseMixin, ImageMixin, TranslatedFieldsMixin):
     """Establishment model."""

apps/establishment/views.py

@@ -111,9 +111,28 @@ class EstablishmentFavoritesCreateDestroyView(generics.CreateAPIView, generics.D
 
         obj = get_object_or_404(
             self.request.user.favorites.by_user(user=self.request.user)
-                                       .by_content_type(app_label='establishment',
-                                                        model='establishment')
-                                       .by_object_id(object_id=self.kwargs['pk']))
+                .by_content_type(app_label='establishment',
+                                 model='establishment')
+                .by_object_id(object_id=self.kwargs['pk']))
         # May raise a permission denied
         self.check_object_permissions(self.request, obj)
         return obj
+
+
+class EstablishmentNearestRetrieveView(EstablishmentMixin, JWTGenericViewMixin, generics.ListAPIView):
+    """Resource for getting list of nearest establishments."""
+    serializer_class = serializers.EstablishmentListSerializer
+    filter_class = filters.EstablishmentFilter
+
+    def get_queryset(self):
+        """Overrided method 'get_queryset'."""
+        from django.contrib.gis.geos import Point
+
+        center = Point(float(self.request.query_params["lat"]), float(self.request.query_params["lon"]))
+        radius = float(self.request.query_params["radius"])
+        unit = self.request.query_params.get("unit", None)
+        by_distance_from_point_kwargs = {"center": center, "radius": radius, "unit": unit}
+        return super(EstablishmentNearestRetrieveView, self).get_queryset() \
+            .by_distance_from_point(**{k: v for k, v in by_distance_from_point_kwargs.items() if v is not None}) \
+            .by_country_code(code=self.request.country_code) \
+            .annotate_in_favorites(user=self.request.user)