1 def add_postgis_srs(srs):

     2     """

     3     This function takes a GDAL SpatialReference system and adds its

     4     information to the PostGIS `spatial_ref_sys` table -- enabling

     5     spatial transformations with PostGIS.  This is handy for adding

     6     spatial reference systems not included by default with PostGIS.  

     7     For example, the following adds the so-called "Google Maps Mercator 

     8     Projection" (available in GDAL 1.5):

     9     

    10     >>> add_postgis_srs(SpatialReference(900913))

    11 

    12     Note: By default, the `auth_name` is set to 'EPSG' -- this should

    13     probably be changed.

    14     """

    15     from django.contrib.gis.models import SpatialRefSys

    16     from django.contrib.gis.gdal import SpatialReference

    17 

    18     if not isinstance(srs, SpatialReference):

    19         srs = SpatialReference(srs)

    20 

    21     if srs.srid is None:

    22         raise Exception('Spatial reference requires an SRID to be compatible with PostGIS.')

    23    

    24     # Creating the spatial_ref_sys model.

    25     sr, created = SpatialRefSys.objects.get_or_create(

    26         srid=srs.srid, auth_name='EPSG', auth_srid=srs.srid, 

    27         srtext=srs.wkt, proj4text=srs.proj4)