[boulder-oracle-sprint] added logic to load a custom QuerySet class from the database backend, if defined. Also added a skeletal Oracle QuerySet.

git-svn-id: http://code.djangoproject.com/svn/django/branches/boulder-oracle-sprint@4000 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/backends/oracle/query.py

@@ -0,0 +1,9 @@
+def get_query_set_class(DefaultQuerySet):
+    """
+    Create a custom QuerySet class for Oracle.
+    """
+    
+    class OracleQuerySet(DefaultQuerySet):
+        pass
+        
+    return OracleQuerySet

django/db/models/query.py

@@ -1,3 +1,4 @@
+from django import db
 from django.db import backend, connection, transaction
 from django.db.models.fields import DateField, FieldDoesNotExist
 from django.db.models import signals
@@ -74,7 +75,7 @@ def quote_only_if_word(word):
     else:
         return backend.quote_name(word)
 
-class QuerySet(object):
+class _QuerySet(object):
     "Represents a lazy database lookup for a set of objects"
     def __init__(self, model=None):
         self.model = model
@@ -556,6 +557,15 @@ class QuerySet(object):
                 full_query = None 
              
             return select, " ".join(sql), params, full_query
+
+# Check to see if the DB backend would like to define its own QuerySet class
+# and otherwise use the default.
+backend_query_module = db.get_query_module()
+if hasattr(backend_query_module, "get_query_set_class"):
+    QuerySet = db.get_query_module().get_query_set_class(_QuerySet)
+else:
+    QuerySet = _QuerySet
+            
 class ValuesQuerySet(QuerySet):
     def iterator(self):
         # select_related and select aren't supported in values().