Fixed the `add_postgis_srs` routine to support SpatiaLite.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10229 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/gis/utils/srs.py

@@ -1,27 +1,49 @@
-def add_postgis_srs(srs):
+def add_postgis_srs(srs, auth_name='EPSG', auth_srid=None, ref_sys_name=None):
     """
     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 
+    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.
+    Keyword Arguments:
+     auth_name: This keyword may be customized with the value of the
+                `auth_name` field.  Defaults to 'EPSG'.
+
+     auth_srid: This keyword may be customized with the value of the
+                `auth_srid` field.  Defaults to the SRID determined
+                by GDAL.
+
+     ref_sys_name: For SpatiaLite users only, sets the value of the
+                   the `ref_sys_name` field.  Defaults to the name
+                   determined by GDAL.
     """
+    from django.contrib.gis.db.backend import SpatialBackend
     from django.contrib.gis.models import SpatialRefSys
     from django.contrib.gis.gdal import SpatialReference
 
+    if SpatialBackend.oracle or SpatialBackend.mysql:
+        raise Exception('This utility not supported on Oracle or MySQL spatial backends.')
+
     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.')
-   
+
+    # Initializing the keyword arguments dictionary for both PostGIS and SpatiaLite.
+    kwargs = {'srid' : srs.srid,
+              'auth_name' : auth_name,
+              'auth_srid' : auth_srid or srs.srid,
+              'proj4text' : srs.proj4,
+              }
+
+    # Backend-specific keyword settings.
+    if SpatialBackend.postgis: kwargs['srtext'] = srs.wkt
+    if SpatialBackend.spatialite: kwargs['ref_sys_name'] = ref_sys_name or srs.name
+
     # 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)
+    sr, created = SpatialRefSys.objects.get_or_create(**kwargs)