custom queryset to allow for order by NULLS LAST

ox/django/query.py

@@ -0,0 +1,61 @@
+# -*- coding: utf-8 -*-
+# vi:si:et:sw=4:sts=4:ts=4
+
+from django.db.models.query import QuerySet
+from django.db.models.sql import Query
+from django.db.models.sql.compiler import SQLCompiler
+from django.db import connections
+
+'''
+models.py:
+-----------------------------------
+from ox.django.query import QuerySet
+
+class Manager(models.Manager):
+    def get_query_set(self):
+        return QuerySet(self.model)
+
+class Model(models.Model):
+    ...
+    objects = Manager()
+'''
+
+class SQLCompiler(SQLCompiler):
+
+    def get_ordering(self):
+        result, group_by = super(SQLCompiler, self).get_ordering()
+        if self.query.nulls_last and len(result):
+            result = map(lambda e: e + ' NULLS LAST', result)
+        return result, group_by
+
+class Query(Query):
+    nulls_last = False
+
+    def clone(self, *args, **kwargs):
+        obj = super(Query, self).clone(*args, **kwargs)
+        obj.nulls_last = self.nulls_last
+        return obj
+
+    def get_compiler(self, using=None, connection=None):
+        if using is None and connection is None:
+            raise ValueError("Need either using or connection")
+        if using:
+            connection = connections[using]
+        # Check that the compiler will be able to execute the query
+        for alias, aggregate in self.aggregate_select.items():
+            connection.ops.check_aggregate_support(aggregate)
+        
+        return SQLCompiler(self, connection, using)
+
+
+class QuerySet(QuerySet):
+
+    def __init__(self, model=None, query=None, using=None):
+        super(QuerySet, self).__init__(model=model, query=query, using=None)
+        self.query = query or Query(self.model)
+
+    def order_by(self, *args, **kwargs):
+        nulls_last = kwargs.pop('nulls_last', False)
+        obj = super(QuerySet, self).order_by(*args, **kwargs)
+        obj.query.nulls_last = nulls_last
+        return obj