Forgot to add the `collect` GeoQuerySet method to correspond to the `Collect`...

        """

        return self._geom_attribute('centroid', **kwargs)

    def collect(self, **kwargs):

        """

        Performs an aggregate collect operation on the given geometry field.

        This is analagous to a union operation, but much faster because

        boundaries are not dissolved.

        """

        return self._spatial_aggregate(aggregates.Collect, **kwargs)

    def difference(self, geom, **kwargs):

        """

        Returns the spatial difference of the geographic field in a `difference`

import os, unittest

from django.contrib.gis.geos import *

from django.contrib.gis.db.backend import SpatialBackend

from django.contrib.gis.db.models import Count, Extent, F, Union

from django.contrib.gis.db.models import Collect, Count, Extent, F, Union

from django.contrib.gis.tests.utils import no_mysql, no_oracle, no_spatialite

from django.conf import settings

from models import City, Location, DirectoryEntry, Parcel, Book, Author

        # Should be `None`, and not a 'dummy' model.

        self.assertEqual(None, b.author)

    @no_mysql

    @no_oracle

    @no_spatialite

    def test14_collect(self):

        "Testing the `collect` GeoQuerySet method and `Collect` aggregate."

        # Reference query:

        # SELECT AsText(ST_Collect("relatedapp_location"."point")) FROM "relatedapp_city" LEFT OUTER JOIN 

        #    "relatedapp_location" ON ("relatedapp_city"."location_id" = "relatedapp_location"."id") 

        #    WHERE "relatedapp_city"."state" = 'TX';

        ref_geom = fromstr('MULTIPOINT(-97.516111 33.058333,-96.801611 32.782057,-95.363151 29.763374,-96.801611 32.782057)')

        c1 = City.objects.filter(state='TX').collect(field_name='location__point')

        c2 = City.objects.filter(state='TX').aggregate(Collect('location__point'))['location__point__collect']

        for coll in (c1, c2):

            # Even though Dallas and Ft. Worth share same point, Collect doesn't

            # consolidate -- that's why 4 points in MultiPoint.

            self.assertEqual(4, len(coll))

            self.assertEqual(ref_geom, coll)

    # TODO: Related tests for KML, GML, and distance lookups.

def suite():