From 9dfee83e687a9aef625fbc38bf5dd10b16e463dc Mon Sep 17 00:00:00 2001
From: Ross Lawley <ross.lawley@gmail.com>
Date: Tue, 7 May 2013 11:54:47 +0000
Subject: [PATCH] Fixed querying string versions of ObjectIds issue with
 ReferenceField (#307)

---
 docs/changelog.rst               |  1 +
 mongoengine/fields.py            |  2 +-
 mongoengine/queryset/queryset.py |  5 ++--
 tests/queryset/queryset.py       | 45 +++++++++++++++++++++++++++++++-
 4 files changed, 49 insertions(+), 4 deletions(-)

diff --git a/docs/changelog.rst b/docs/changelog.rst
index ad5f6157..842bc7d0 100644
--- a/docs/changelog.rst
+++ b/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)
diff --git a/mongoengine/fields.py b/mongoengine/fields.py
index 49959983..573d9a03 100644
--- a/mongoengine/fields.py
+++ b/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]
diff --git a/mongoengine/queryset/queryset.py b/mongoengine/queryset/queryset.py
index 85b683db..191afdd2 100644
--- a/mongoengine/queryset/queryset.py
+++ b/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
-        a maximum depth in order to cut down the number queries to mongodb.
+        """Handles dereferencing of :class:`~bson.dbref.DBRef` objects or
+        :class:`~bson.object_id.ObjectId` a maximum depth in order to cut down
+        the number queries to mongodb.
 
         .. versionadded:: 0.5
         """
diff --git a/tests/queryset/queryset.py b/tests/queryset/queryset.py
index ffb53786..b9db297b 100644
--- a/tests/queryset/queryset.py
+++ b/tests/queryset/queryset.py
@@ -1263,7 +1263,7 @@ class QuerySetTest(unittest.TestCase):
         class BlogPost(Document):
             content = StringField()
             authors = ListField(ReferenceField(self.Person,
-                reverse_delete_rule=PULL))
+                                reverse_delete_rule=PULL))
 
         BlogPost.drop_collection()
         self.Person.drop_collection()
@@ -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.
         """