Hey guys, I'm working with the GeoDjango branch and I was wondering if
there are any plans to allow something like I have below:

"parcel" is a foreign key to the geometry model information:

class Parcel(models.Model,models.GeoMixin):
    gid = models.IntegerField(db_column='gid',primary_key=True)
    apn = models.CharField(db_column='apn',maxlength=10)
    poly = models.PolygonField(db_column='the_geom',srid=4269,
index=True)
    zip = models.CharField(db_column='zip', maxlength=5)
    objects = models.GeoManager()

I can do spatial queries if they are directly between two models with
polygon fields but I can't seem to get at the spatial queries through
foreign keys.

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/django_gis/django/db/models/query.py", line
102, in __repr__
    return repr(self._get_data())
  File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/django_gis/django/db/models/query.py", line
470, in _get_data
    self._result_cache = list(self.iterator())
  File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/django_gis/django/db/models/query.py", line
174, in iterator
    select, sql, params = self._get_sql_clause()
  File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/django_gis/django/db/models/query.py", line
484, in _get_sql_clause
    joins2, where2, params2 = self._filters.get_sql(opts)
  File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/django_gis/django/db/models/query.py", line
648, in get_sql
    joins2, where2, params2 = val.get_sql(opts)
  File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/django_gis/django/db/models/query.py", line
699, in get_sql
    return parse_lookup(self.kwargs.items(), opts)
  File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/django_gis/django/db/models/query.py", line
831, in parse_lookup
    joins2, where2, params2 = lookup_inner(path, lookup_type, value,
opts, opts.db_table, None)
  File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/django_gis/django/db/models/query.py", line
970, in lookup_inner
    joins2, where2, params2 = lookup_inner(path, lookup_type, value,
new_opts, new_table, join_column)
  File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/django_gis/django/db/models/query.py", line
938, in lookup_inner
    raise TypeError, "Cannot resolve keyword '%s' into field" % name
TypeError: Cannot resolve keyword 'poly__contained' into field

Thanks,
Matt

I wouldn't think this would actually work but I just put the objects =
models.GeoManager() on my model and it now knows what to do with the
spatial queries. Excellent.

On 4/17/07, mattxbart <mattxb...@gmail.com> wrote:

Matt,

That's a good point you brought up: if there's a ForeignKey to a model
with a geographic field, then the model with the ForeignKey requires
GeoManager to construct geographic queries on related objects (even if
the model itself does not have geographic fields).

The GeoManager overrides the regular Manager to return GeoQuerySet
objects (instead of QuerySet).  The GeoQuerySet objects have their own
parse_lookup() function that constructs the SQL for the geographic
queries.  While its almost verbatim from the 'original' parse_lookup()
in django/db/models/query.py, it has a few changes that allow it to
use the PostGIS lookup types.  Thus, when you have no GeoManager, the
regular Manager is used and it has no clue what to do with the
geographic lookup types.  Therefore, GeoManager needs to be used
whenever geographic queries are needed.

I'll try and put something in the GeoDjango FAQ about this.  Thanks
for posting your experience and solution.

-Justin Bronn