Fixed querying string versions of ObjectIds issue with ReferenceField (#307)

docs/changelog.rst

@@ -4,6 +4,7 @@ Changelog
 
 Changes in 0.8.0
 ================
+- Fixed querying string versions of ObjectIds issue with ReferenceField (#307)
 - Added $setOnInsert support for upserts (#308)
 - Upserts now possible with just query parameters (#309)
 - Upserting is the only way to ensure docs are saved correctly (#306)

mongoengine/fields.py

@@ -854,7 +854,7 @@ class ReferenceField(BaseField):
                 return document.id
             return document
         elif not self.dbref and isinstance(document, basestring):
-            return document
+            return ObjectId(document)
 
         id_field_name = self.document_type._meta['id_field']
         id_field = self.document_type._fields[id_field_name]

mongoengine/queryset/queryset.py

@@ -544,8 +544,9 @@ class QuerySet(object):
         return c
 
     def select_related(self, max_depth=1):
-        """Handles dereferencing of :class:`~bson.dbref.DBRef` objects to
+        """Handles dereferencing of :class:`~bson.dbref.DBRef` objects or
-        a maximum depth in order to cut down the number queries to mongodb.
+        :class:`~bson.object_id.ObjectId` a maximum depth in order to cut down
+        the number queries to mongodb.
 
         .. versionadded:: 0.5
         """

tests/queryset/queryset.py

@@ -1321,6 +1321,49 @@ class QuerySetTest(unittest.TestCase):
         self.Person.objects()[:1].delete()
         self.assertEqual(1, BlogPost.objects.count())
 
+
+    def test_reference_field_find(self):
+        """Ensure cascading deletion of referring documents from the database.
+        """
+        class BlogPost(Document):
+            content = StringField()
+            author = ReferenceField(self.Person)
+
+        BlogPost.drop_collection()
+        self.Person.drop_collection()
+
+        me = self.Person(name='Test User').save()
+        BlogPost(content="test 123", author=me).save()
+
+        self.assertEqual(1, BlogPost.objects(author=me).count())
+        self.assertEqual(1, BlogPost.objects(author=me.pk).count())
+        self.assertEqual(1, BlogPost.objects(author="%s" % me.pk).count())
+
+        self.assertEqual(1, BlogPost.objects(author__in=[me]).count())
+        self.assertEqual(1, BlogPost.objects(author__in=[me.pk]).count())
+        self.assertEqual(1, BlogPost.objects(author__in=["%s" % me.pk]).count())
+
+    def test_reference_field_find_dbref(self):
+        """Ensure cascading deletion of referring documents from the database.
+        """
+        class BlogPost(Document):
+            content = StringField()
+            author = ReferenceField(self.Person, dbref=True)
+
+        BlogPost.drop_collection()
+        self.Person.drop_collection()
+
+        me = self.Person(name='Test User').save()
+        BlogPost(content="test 123", author=me).save()
+
+        self.assertEqual(1, BlogPost.objects(author=me).count())
+        self.assertEqual(1, BlogPost.objects(author=me.pk).count())
+        self.assertEqual(1, BlogPost.objects(author="%s" % me.pk).count())
+
+        self.assertEqual(1, BlogPost.objects(author__in=[me]).count())
+        self.assertEqual(1, BlogPost.objects(author__in=[me.pk]).count())
+        self.assertEqual(1, BlogPost.objects(author__in=["%s" % me.pk]).count())
+
     def test_update(self):
         """Ensure that atomic updates work properly.
         """