Fix regression with Django < 1.9

polymorphic/query.py

@@ -8,7 +8,7 @@ import copy
 from collections import defaultdict
 
 import django
-from django.db.models.query import ModelIterable, QuerySet, Q
+from django.db.models.query import QuerySet, Q
 from django.contrib.contenttypes.models import ContentType
 from django.utils import six
 
@@ -25,26 +25,11 @@ except ImportError:
 Polymorphic_QuerySet_objects_per_request = CHUNK_SIZE
 
 
-class PolymorphicModelIterable(ModelIterable):
+def _polymorhic_iterator(queryset, base_iter):
-    """
-    ModelIterable for PolymorphicModel
-
-    Yields real instances if qs.polymorphic_disabled is False,
-    otherwise acts like a regular ModelIterable.
-    """
-
-    def __iter__(self):
-        base_iter = super(PolymorphicModelIterable, self).__iter__()
-        if self.queryset.polymorphic_disabled:
-            return base_iter
-        return self._polymorhic_iterator(base_iter)
-
-    def _polymorhic_iterator(self, base_iter):
     """
     Here we do the same as::
 
-            base_result_objects = list(super(PolymorphicModelIterable, self).__iter__())
+        real_results = queryset._get_real_instances(list(base_iter))
-            real_results = self.queryset._get_real_instances(base_result_objects)
         for o in real_results: yield o
 
     but it requests the objects in chunks from the database,
@@ -62,7 +47,7 @@ class PolymorphicModelIterable(ModelIterable):
                 reached_end = True
                 break
 
-            real_results = self.queryset._get_real_instances(base_result_objects)
+        real_results = queryset._get_real_instances(base_result_objects)
 
         for o in real_results:
             yield o
@@ -71,6 +56,25 @@ class PolymorphicModelIterable(ModelIterable):
             return
 
 
+if django.VERSION >= (1, 9):
+
+    from django.db.models.query import ModelIterable
+
+    class PolymorphicModelIterable(ModelIterable):
+        """
+        ModelIterable for PolymorphicModel
+
+        Yields real instances if qs.polymorphic_disabled is False,
+        otherwise acts like a regular ModelIterable.
+        """
+
+        def __iter__(self):
+            base_iter = super(PolymorphicModelIterable, self).__iter__()
+            if self.queryset.polymorphic_disabled:
+                return base_iter
+            return _polymorhic_iterator(self.queryset, base_iter)
+
+
 def transmogrify(cls, obj):
     """
     Upcast a class to a different type without asking questions.
@@ -110,6 +114,7 @@ class PolymorphicQuerySet(QuerySet):
 
     def __init__(self, *args, **kwargs):
         super(PolymorphicQuerySet, self).__init__(*args, **kwargs)
+        if django.VERSION >= (1, 9):
             self._iterable_class = PolymorphicModelIterable
         # init our queryset object member variables
         self.polymorphic_disabled = False
@@ -454,6 +459,20 @@ class PolymorphicQuerySet(QuerySet):
 
         return resultlist
 
+    if django.VERSION < (1, 9):
+        # Before Django 1.9 ModelIterable functionality was implemented in `iterator` method
+        def iterator(self):
+            base_iter = super(PolymorphicQuerySet, self).iterator()
+
+            # disabled => work just like a normal queryset
+            if self.polymorphic_disabled:
+                for o in base_iter:
+                    yield o
+                return
+
+            for o in _polymorhic_iterator(self, base_iter):
+                yield o
+
     def __repr__(self, *args, **kwargs):
         if self.model.polymorphic_query_multiline_output:
             result = [repr(o) for o in self.all()]