Merge branch 'emilecaron-master'

AUTHORS

@@ -226,4 +226,4 @@ that much better:
  * Emmanuel Leblond (https://github.com/touilleMan)
  * Breeze.Kay (https://github.com/9nix00)
  * Vicki Donchenko (https://github.com/kivistein)
-
+ * Emile Caron (https://github.com/emilecaron)

docs/changelog.rst

@@ -4,6 +4,7 @@ Changelog
 
 Changes in 0.10.1 - DEV
 =======================
+- Fix infinite recursion with CASCADE delete rules under specific conditions. #1046
 
 Changes in 0.10.0
 =================

mongoengine/queryset/base.py

@@ -346,7 +346,7 @@ class BaseQuerySet(object):
             return 0
         return self._cursor.count(with_limit_and_skip=with_limit_and_skip)
 
-    def delete(self, write_concern=None, _from_doc_delete=False):
+    def delete(self, write_concern=None, _from_doc_delete=False, cascade_refs=None):
         """Delete the documents matched by the query.
 
         :param write_concern: Extra keyword arguments are passed down which
@@ -402,11 +402,13 @@ class BaseQuerySet(object):
                 continue
             rule = doc._meta['delete_rules'][rule_entry]
             if rule == CASCADE:
-                ref_q = document_cls.objects(**{field_name + '__in': self})
+                cascade_refs = set() if cascade_refs is None else cascade_refs
+                for ref in queryset:
+                    cascade_refs.add(ref.id)
+                ref_q = document_cls.objects(**{field_name + '__in': self, 'id__nin': cascade_refs})
                 ref_q_count = ref_q.count()
-                if (doc != document_cls and ref_q_count > 0 or
-                        (doc == document_cls and ref_q_count > 0)):
-                    ref_q.delete(write_concern=write_concern)
+                if ref_q_count > 0:
+                    ref_q.delete(write_concern=write_concern, cascade_refs=cascade_refs)
             elif rule == NULLIFY:
                 document_cls.objects(**{field_name + '__in': self}).update(
                     write_concern=write_concern, **{'unset__%s' % field_name: 1})

tests/queryset/queryset.py

@@ -1413,6 +1413,47 @@ class QuerySetTest(unittest.TestCase):
         self.Person.objects(name='Test User').delete()
         self.assertEqual(1, BlogPost.objects.count())
 
+    def test_reverse_delete_rule_cascade_cycle(self):
+        """Ensure reference cascading doesn't loop if reference graph isn't
+        a tree
+        """
+        class Dummy(Document):
+            reference = ReferenceField('self', reverse_delete_rule=CASCADE)
+
+        base = Dummy().save()
+        other = Dummy(reference=base).save()
+        base.reference = other
+        base.save()
+
+        base.delete()
+
+        self.assertRaises(DoesNotExist, base.reload)
+        self.assertRaises(DoesNotExist, other.reload)
+
+    def test_reverse_delete_rule_cascade_complex_cycle(self):
+        """Ensure reference cascading doesn't loop if reference graph isn't
+        a tree
+        """
+        class Category(Document):
+            name = StringField()
+
+        class Dummy(Document):
+            reference = ReferenceField('self', reverse_delete_rule=CASCADE)
+            cat = ReferenceField(Category, reverse_delete_rule=CASCADE)
+
+        cat = Category(name='cat').save()
+        base = Dummy(cat=cat).save()
+        other = Dummy(reference=base).save()
+        other2 = Dummy(reference=other).save()
+        base.reference = other
+        base.save()
+
+        cat.delete()
+
+        self.assertRaises(DoesNotExist, base.reload)
+        self.assertRaises(DoesNotExist, other.reload)
+        self.assertRaises(DoesNotExist, other2.reload)
+
     def test_reverse_delete_rule_cascade_self_referencing(self):
         """Ensure self-referencing CASCADE deletes do not result in infinite
         loop