SRSException: Invalid spatial reference pointer returned from
"OGR_L_GetSpatialRef".

This occurs on both Debian Etch and OS X 10.4 (both are using GDAL
version 1.4.2 and python 2.4 with ctypes package installed). I'm just
starting out with GeoDjango so I'm not sure if it's an installation
problem or the code. I was able to successfully run the third-party
library installation tests at [4] and also the DataSource example at
[5], in case that helps to shed any light on the soundness of my
installation.

Should the example still work with the latest svn revision of
GeoDjango? The IPython session is pasted below.

Thanks,
Joe

[1] http://www.foss4g2007.org/presentations/viewattachment.php?attachment...
[2] http://www.foss4g2007.org/presentations/view.php?abstract_id=222
[3] http://www.census.gov/geo/cob/bdy/st/st00shp/st99_d00_shp.zip
[4] http://code.djangoproject.com/wiki/GeoDjangoInstall#Third-PartyLibrar...
[5] http://code.djangoproject.com/wiki/GeoDjangoExtras#DataSource

This IPython session is also pasted at http://dpaste.com/hold/27869/ :
==========================================================================

In [1]: from django.contrib.gis.utils import ogrinfo

In [2]: ogrinfo('st99_d00.shp',num_features=1)
data source : st99_d00.shp
==== layer 0
  shape type: Polygon
  # features: 273
---------------------------------------------------------------------------
django.contrib.gis.gdal.error.SRSException
 Traceback (most recent call last)

/home/joe/foss4g/<ipython console>

/usr/lib/python2.4/site-packages/django/contrib/gis/utils/ogrinfo.py
in ogrinfo(data_source, num_features)
     27         print "  shape type: %s" %
GEO_CLASSES[layer.geom_type.num].__name__
     28         print "  # features: %s" % len(layer)
---> 29         print "         srs: %s" % layer.srs
     30         extent_tup = layer.extent.tuple
     31         print "      extent: %s - %s" % (extent_tup[0:2],
extent_tup[2:4])

/usr/lib/python2.4/site-packages/django/contrib/gis/gdal/layer.py in srs(self)
    100     def srs(self):
    101         "Returns the Spatial Reference used in this Layer."
--> 102         ptr = get_layer_srs(self._ptr)
    103         if ptr:
    104             return SpatialReference(clone_srs(ptr))

/usr/lib/python2.4/site-packages/django/contrib/gis/gdal/prototypes/errchec k.py
in check_srs(result, func, cargs)
     89         result = c_void_p(result)
     90     if not result:
---> 91         raise SRSException('Invalid spatial reference pointer
returned from "%s".' % func.__name__)
     92     return result
     93

SRSException: Invalid spatial reference pointer returned from
"OGR_L_GetSpatialRef".

There have been some significant changes to GeoDjango since FOSS4G
(e.g., GEOS & GDAL refactors, distance queries, additional spatial
backends).  However, substantively, everything should still work as
shown.  This particular bug is an artifact of the GDAL library
refactoring: the census shapefiles do not explicitly give a spatial
reference, which is NAD83, and the `srs` property should be None
instead of raising an exception.  One thing that has explicitly
changed is that `models.GeoMixin` is no longer required for geographic
models.

Thanks for the detailed report and traceback.

Best Regards,
-Justin

Thanks,
Joe