Introduce dynamic scope_path regexps Instead of relying on scope_path's being "one slash deep", we should instead allow for either: 1. scope_paths that have a pre-defined depth 2. scope_paths that can be arbitrarily deep We achieve 1 by setting an entities scope_logic to another logic module. We then recursively call getScopeDepth until we get to the topmost entity (that is, an unscoped entity). A little different is the solution to 2, since some entities can have an arbitrarily deep scope (such as Documents), we need to have some way of signaling this to getScopePattern. A clean solution is to return None, rather than a number. If None is returned, the SCOPE_PATH_ARG_PATTERN is returned as regexp instead, which will match an arbitrarily deeply nested scope. The solution for 2 requires that we return None somewhere in the scope_logic chain, the most straight forward method to do so is to override getScopeDepth anywhere such a scope is needed and make it return None. A more elegant solution however, is to set the scope_logic to that module in all entities that require it. Patch by: Sverre Rabbelier

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)