--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/web/lib/django/contrib/gis/db/models/aggregates.py	Wed Jan 20 00:34:04 2010 +0100
@@ -0,0 +1,31 @@
+from django.db.models import Aggregate
+from django.contrib.gis.db.backend import SpatialBackend
+from django.contrib.gis.db.models.sql import GeomField
+
+class GeoAggregate(Aggregate):
+
+    def add_to_query(self, query, alias, col, source, is_summary):
+        if hasattr(source, 'geom_type'):
+            # Doing additional setup on the Query object for spatial aggregates.
+            aggregate = getattr(query.aggregates_module, self.name)
+            
+            # Adding a conversion class instance and any selection wrapping
+            # SQL (e.g., needed by Oracle).
+            if aggregate.conversion_class is GeomField:
+                query.extra_select_fields[alias] = GeomField()
+                if SpatialBackend.select:
+                    query.custom_select[alias] = SpatialBackend.select
+     
+        super(GeoAggregate, self).add_to_query(query, alias, col, source, is_summary)
+
+class Collect(GeoAggregate):
+    name = 'Collect'
+
+class Extent(GeoAggregate):
+    name = 'Extent'
+
+class MakeLine(GeoAggregate):
+    name = 'MakeLine'
+
+class Union(GeoAggregate):
+    name = 'Union'