Fix bounding box calculation for spatial queries (closes django-haystack#718)

Thanks @jasisz for the fix

Author: acdha

AUTHORS

@@ -86,3 +86,4 @@ Thanks to
     * Revolution Systems & The Python Software Foundation for funding a significant portion of the port to Python 3!
     * Artem Kostiuk (postatum) for patch allowing to search for slash character in ElasticSearch since Lucene 4.0.
     * Luis Barrueco (luisbarrueco) for a simple fix regarding updating indexes using multiple backends.
+    * Szymon Teżewski (jasisz) for an update to the bounding-box calculation for spatial queries

docs/spatial.rst

@@ -218,9 +218,7 @@ finding results within an area.
 
 ``within`` is a bounding box comparison. A bounding box is a rectangular area
 within which to search. It's composed of a bottom-left point & a top-right
-point, though provided you give two opposing corners in either order, Haystack
-will determine the right coordinates. It is faster but slighty sloppier than
-its counterpart.
+point. It is faster but slighty sloppier than its counterpart.
 
 Examples::
 

haystack/backends/elasticsearch_backend.py

@@ -418,17 +418,17 @@ def build_search_kwargs(self, query_string, sort_by=None, start_offset=0, end_of
         if within is not None:
             from haystack.utils.geo import generate_bounding_box
 
-            ((min_lat, min_lng), (max_lat, max_lng)) = generate_bounding_box(within['point_1'], within['point_2'])
+            ((south, west), (north, east)) = generate_bounding_box(within['point_1'], within['point_2'])
             within_filter = {
                 "geo_bounding_box": {
                     within['field']: {
                         "top_left": {
-                            "lat": max_lat,
-                            "lon": min_lng
+                            "lat": north,
+                            "lon": west
                         },
                         "bottom_right": {
-                            "lat": min_lat,
-                            "lon": max_lng
+                            "lat": south,
+                            "lon": east
                         }
                     }
                 },

haystack/utils/geo.py

@@ -61,15 +61,14 @@ def ensure_distance(dist):
     return dist
 
 
-def generate_bounding_box(point_1, point_2):
+def generate_bounding_box(bottom_left, top_right):
     """
-    Takes two opposite corners of a bounding box (in any order) & generates
+    Takes two opposite corners of a bounding box (order matters!) & generates
     a two-tuple of the correct coordinates for the bounding box.
 
     The two-tuple is in the form ``((min_lat, min_lng), (max_lat, max_lng))``.
     """
-    lng_1, lat_1 = point_1.get_coords()
-    lng_2, lat_2 = point_2.get_coords()
+    west, lat_1 = bottom_left.get_coords()
+    east, lat_2 = top_right.get_coords()
     min_lat, max_lat = min(lat_1, lat_2), max(lat_1, lat_2)
-    min_lng, max_lng = min(lng_1, lng_2), max(lng_1, lng_2)
-    return ((min_lat, min_lng), (max_lat, max_lng))
+    return ((min_lat, west), (max_lat, east))

tests/spatial/tests.py

@@ -54,6 +54,15 @@ def test_generate_bounding_box(self):
         self.assertEqual(max_lat, 38.973081081164715)
         self.assertEqual(max_lng, -95.23362278938293)
 
+    def test_generate_bounding_box_crossing_line_date(self):
+        downtown_bottom_left = Point(95.23947, 38.9637903)
+        downtown_top_right = Point(-95.23362278938293, 38.973081081164715)
+        ((south, west), (north, east)) = generate_bounding_box(downtown_bottom_left, downtown_top_right)
+        self.assertEqual(south, 38.9637903)
+        self.assertEqual(west, 95.23947)
+        self.assertEqual(north, 38.973081081164715)
+        self.assertEqual(east, -95.23362278938293)
+
 
 class SpatialSolrNoDistanceTestCase(TestCase):
     fixtures = ['sample_spatial_data.json']