GeoQuerySet methods should filter out NULL values by default

[Nathaniel Whiteinge]

Given the following GIS model:

    class SomeModel(models.Model):
        location = models.PointField(null=True)
        <snip>

When populated with instances that both have and do not have location information, doing a distance(geom) query yields unexpected results.

For example, SomeModel.objects.distance(somePoint) returns no results at all. SomeModel.objects.filter(location__isnull=False).distance(somePoint) works as expected.

IMO, distance(geom) results that cannot calculate distance should simply return None.

[Charlie DeTar]

Prevent null geometry fields from resulting in empty querysets

[Charlie DeTar]

The problem seems to arise from line 49 in django/contrib/gis/measure.py

            if not isinstance(value, float): value = float(value)

Where "value" is the value of the geometry field. If the field is null, this becomes None, and propagates a ValueError up the stack resulting in an empty queryset.

I'm attaching a patch which fixes this by altering the method which constructs geometry objects out of the measurement attributes to instead keep the attribute as "None" if the value is None.

[Charlie DeTar]

Updated diff that includes tests

[jbronn]

(In [12885]) Fixed #10594 -- GeoQuerySet measurment methods no longer crash on geometry fields with NULL values. Thanks, whiteinge for the bug report and yourcelf for the initial patch.

[jbronn]

(In [12886]) [1.1.X] Fixed #10594 -- GeoQuerySet measurment methods no longer crash on geometry fields with NULL values. Thanks, whiteinge for the bug report and yourcelf for the initial patch.

Backport of r12885 from trunk.

[Jacob]

Milestone 1.2 deleted