Use ST_Covers not ST_Contains for subdivision point lookup

ST_Contains doesn’t match if the point is on the boundary of
the subdivision.

mapit/models.py

@@ -166,8 +166,8 @@ def get_queryset(self):
     def by_location(self, location, query):
         if not location:
             return []
-        query &= Q(polygons__subdivided__division__contains=location)
-        return Area.objects.filter(query)
+        query &= Q(polygons__subdivided__division__covers=location)
+        return Area.objects.filter(query).distinct()
 
     def by_postcode(self, postcode, query):
         return list(itertools.chain(

mapit/tests/test_views.py

@@ -97,6 +97,20 @@ def test_areas_by_point(self):
             set((x.id for x in (self.big_area, self.small_area_1)))
             )
 
+    def test_subdivided_areas_by_point(self):
+        # Choose a point that is directly on the boundary of a subdivision, and ensure that
+        # looking up the areas for that point returns the correct area.
+        (x, y) = self.big_shape.subdivided.first().division.coords[0][1]
+        url = f'/point/{settings.MAPIT_AREA_SRID}/{x},{y}.json'
+        response = self.client.get(url, HTTP_ACCEPT_ENCODING='gzip')
+
+        content = get_content(response)
+
+        self.assertEqual(
+            int(list(content.keys())[0]),
+            self.big_area.id
+        )
+
     @override_settings(MAPIT_WITHIN_MAXIMUM=1000)
     def test_areas_by_point_within(self):
         url = '/point/4326/-4.001,51.json?within=Bad'

mapit/views/areas.py

@@ -400,11 +400,11 @@ def areas_by_point(request, srid, x, y, bb=False, format=''):
         raise ViewException(format, _('Bad "within" parameter specified'), 400)
 
     if method == 'box':
-        q &= Q(polygons__subdivided__division__bbcontains=location)
+        q &= Q(polygons__subdivided__division__bbcovers=location)
     elif within:
         q &= Q(polygons__subdivided__division__dwithin=(location, within))
     else:
-        q &= Q(polygons__subdivided__division__contains=location)
+        q &= Q(polygons__subdivided__division__covers=location)
     areas = Area.objects.filter(q).distinct()
 
     return output_areas(