app/django/contrib/gis/utils/srs.py
author Madhusudan C.S. <madhusudancs@gmail.com>
Tue, 11 Aug 2009 12:48:10 -0700
changeset 2757 7d0d0ce76bd9
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
updateOrCreateFromFields is made to call updateOrCreateFromKeyName. updateOrCreateFromFields called self._model.get_or_insert which only creates new entities but doesn't update the properties if the entity already exists. So updateOrCreateFromFields is now made to call updateOrCreateFromKeyName which actually updates the entity properties if entity already exists. Reviewed by: Lennard de Rijk

def add_postgis_srs(srs):
    """
    This function takes a GDAL SpatialReference system and adds its
    information to the PostGIS `spatial_ref_sys` table -- enabling
    spatial transformations with PostGIS.  This is handy for adding
    spatial reference systems not included by default with PostGIS.  
    For example, the following adds the so-called "Google Maps Mercator 
    Projection" (available in GDAL 1.5):
    
    >>> add_postgis_srs(SpatialReference(900913))

    Note: By default, the `auth_name` is set to 'EPSG' -- this should
    probably be changed.
    """
    from django.contrib.gis.models import SpatialRefSys
    from django.contrib.gis.gdal import SpatialReference

    if not isinstance(srs, SpatialReference):
        srs = SpatialReference(srs)

    if srs.srid is None:
        raise Exception('Spatial reference requires an SRID to be compatible with PostGIS.')
   
    # Creating the spatial_ref_sys model.
    sr, created = SpatialRefSys.objects.get_or_create(
        srid=srs.srid, auth_name='EPSG', auth_srid=srs.srid, 
        srtext=srs.wkt, proj4text=srs.proj4)