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Viewing changes to trunk/python-packages/django/contrib/gis/utils/srs.py

  • Committer: Matthew Nuzum
  • Date: 2008-11-13 05:46:03 UTC
  • Revision ID: matthew.nuzum@canonical.com-20081113054603-v0kvr6z6xyexvqt3
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trunk/python-packages/django/contrib/gis/utils/srs.py
 
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def add_postgis_srs(srs):
 
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    """
 
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    This function takes a GDAL SpatialReference system and adds its
 
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    information to the PostGIS `spatial_ref_sys` table -- enabling
 
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    spatial transformations with PostGIS.  This is handy for adding
 
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    spatial reference systems not included by default with PostGIS.  
 
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    For example, the following adds the so-called "Google Maps Mercator 
 
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    Projection" (available in GDAL 1.5):
 
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    >>> add_postgis_srs(SpatialReference(900913))
 
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    Note: By default, the `auth_name` is set to 'EPSG' -- this should
 
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    probably be changed.
 
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    """
 
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    from django.contrib.gis.models import SpatialRefSys
 
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    from django.contrib.gis.gdal import SpatialReference
 
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    if not isinstance(srs, SpatialReference):
 
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        srs = SpatialReference(srs)
 
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    if srs.srid is None:
 
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        raise Exception('Spatial reference requires an SRID to be compatible with PostGIS.')
 
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    # Creating the spatial_ref_sys model.
 
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    sr, created = SpatialRefSys.objects.get_or_create(
 
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        srid=srs.srid, auth_name='EPSG', auth_srid=srs.srid, 
 
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        srtext=srs.wkt, proj4text=srs.proj4)