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

"""
 This module provides the backend for spatial SQL construction with Django.

 Specifically, this module will import the correct routines and modules
 needed for GeoDjango to interface with the spatial database.
"""
from django.conf import settings
from django.contrib.gis.db.backend.util import gqn

# Retrieving the necessary settings from the backend.
if settings.DATABASE_ENGINE == 'postgresql_psycopg2':
    from django.contrib.gis.db.backend.postgis import create_spatial_db, get_geo_where_clause, SpatialBackend
elif settings.DATABASE_ENGINE == 'oracle':
    from django.contrib.gis.db.backend.oracle import create_spatial_db, get_geo_where_clause, SpatialBackend
elif settings.DATABASE_ENGINE == 'mysql':
    from django.contrib.gis.db.backend.mysql import create_spatial_db, get_geo_where_clause, SpatialBackend
else:
    raise NotImplementedError('No Geographic Backend exists for %s' % settings.DATABASE_ENGINE)