Fixed #12591 -- Renamed `add_postgis_srs` to `add_srs_entry` (keeping backwards-compatible alias), added `database` keyword for multi-db, removed deprecated `SpatialBackend` references; no longer use `get_or_create` and look for existing entry based on SRID value.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12228 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/gis/utils/__init__.py

@@ -6,7 +6,7 @@ from django.contrib.gis.gdal import HAS_GDAL
 if HAS_GDAL:
     from django.contrib.gis.utils.ogrinfo import ogrinfo, sample
     from django.contrib.gis.utils.ogrinspect import mapping, ogrinspect
-    from django.contrib.gis.utils.srs import add_postgis_srs
+    from django.contrib.gis.utils.srs import add_postgis_srs, add_srs_entry
     try:
         # LayerMapping requires DJANGO_SETTINGS_MODULE to be set, 
         # so this needs to be in try/except.

django/contrib/gis/utils/srs.py

@@ -1,49 +1,77 @@
-def add_postgis_srs(srs, auth_name='EPSG', auth_srid=None, ref_sys_name=None):
+from django.contrib.gis.gdal import SpatialReference
+from django.db import connections, DEFAULT_DB_ALIAS
+
+def add_srs_entry(srs, auth_name='EPSG', auth_srid=None, ref_sys_name=None,
+                  database=DEFAULT_DB_ALIAS):
     """
-    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):
+    This function takes a GDAL SpatialReference system and adds its information
+    to the `spatial_ref_sys` table of the spatial backend.  Doing this enables
+    database-level spatial transformations for the backend.  Thus, this utility
+    is useful for adding spatial reference systems not included by default with
+    the backend -- for example, the so-called "Google Maps Mercator Projection"
+    is excluded in PostGIS 1.3 and below, and the following adds it to the
+    `spatial_ref_sys` table:
 
-    >>> add_postgis_srs(SpatialReference(900913))
+    >>> from django.contrib.gis.utils import add_srs_entry
+    >>> add_srs_entry(900913)
 
     Keyword Arguments:
-     auth_name: This keyword may be customized with the value of the
-                `auth_name` field.  Defaults to 'EPSG'.
+     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.
+     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
+     ref_sys_name:
+       For SpatiaLite users only, sets the value of the the `ref_sys_name` field.
+       Defaults to the name determined by GDAL.
 
-    if SpatialBackend.oracle or SpatialBackend.mysql:
-        raise Exception('This utility not supported on Oracle or MySQL spatial backends.')
+     database:
+      The name of the database connection to use; the default is the value
+      of `django.db.DEFAULT_DB_ALIAS` (at the time of this writing, it's value
+      is 'default').
+    """
+    connection = connections[database]
+    if not hasattr(connection.ops, 'spatial_version'):
+        raise Exception('The `add_srs_entry` utility only works '
+                        'with spatial backends.')
+    if connection.ops.oracle or connection.ops.mysql:
+        raise Exception('This utility does not support the '
+                        'Oracle or MySQL spatial backends.')
+    SpatialRefSys = connection.ops.spatial_ref_sys()
 
+    # If argument is not a `SpatialReference` instance, use it as parameter
+    # to construct a `SpatialReference` instance.
     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.')
+        raise Exception('Spatial reference requires an SRID to be '
+                        'compatible with the spatial backend.')
 
-    # Initializing the keyword arguments dictionary for both PostGIS and SpatiaLite.
+    # 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
+    # Backend-specific fields for the SpatialRefSys model.
+    if connection.ops.postgis:
+        kwargs['srtext'] = srs.wkt
+    if connection.ops.spatialite:
+        kwargs['ref_sys_name'] = ref_sys_name or srs.name
 
     # Creating the spatial_ref_sys model.
-    sr, created = SpatialRefSys.objects.get_or_create(**kwargs)
+    try:
+        # Try getting via SRID only, because using all kwargs may
+        # differ from exact wkt/proj in database.
+        sr = SpatialRefSys.objects.get(srid=srs.srid)
+    except SpatialRefSys.DoesNotExist:
+        sr = SpatialRefSys.objects.create(**kwargs)
+
+# Alias is for backwards-compatibility purposes.
+add_postgis_srs = add_srs_entry