From e231f71b4a373c103084636f8647e1328843f527 Mon Sep 17 00:00:00 2001
From: Ross Lawley <ross.lawley@gmail.com>
Date: Fri, 2 Dec 2011 02:46:55 -0800
Subject: [PATCH] EmbeddedDocuments dont support Reverse Delete Rules

Now throws an InvalidDocumentError

Refs #227
---
 docs/upgrade.rst    |  5 +++--
 mongoengine/base.py | 14 ++++++++++++++
 tests/document.py   |  8 ++++++++
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/docs/upgrade.rst b/docs/upgrade.rst
index 1b25c076..cb72b356 100644
--- a/docs/upgrade.rst
+++ b/docs/upgrade.rst
@@ -8,10 +8,11 @@ Upgrading
 Embedded Documents - if you had a `pk` field you will have to rename it from `_id`
 to `pk` as pk is no longer a property of Embedded Documents.
 
+Reverse Delete Rules in Embedded Documents, MapFields and DictFields now throw
+an InvalidDocument error as they aren't currently supported.
+
 Document._get_subclasses - Is no longer used and the class method has been removed.
 
-Reverse Delete Rules on MapFields and DictFields now throw a InvalidDocument error
-as they aren't supported.
 
 0.4 to 0.5
 ===========
diff --git a/mongoengine/base.py b/mongoengine/base.py
index 29be8764..00dd2eeb 100644
--- a/mongoengine/base.py
+++ b/mongoengine/base.py
@@ -518,6 +518,8 @@ class DocumentMetaclass(type):
                 f = field.field
 
             if delete_rule != DO_NOTHING:
+                if issubclass(new_class, EmbeddedDocument):
+                    raise InvalidDocumentError("Reverse delete rules are not supported for EmbeddedDocuments (field: %s)" % field.name)
                 f.document_type.register_delete_rule(new_class, field.name, delete_rule)
 
             if field.name and hasattr(Document, field.name) and EmbeddedDocument not in new_class.mro():
@@ -663,6 +665,18 @@ class TopLevelDocumentMetaclass(DocumentMetaclass):
 
         return new_class
 
+    def __instancecheck__(cls, inst):
+        """Custom instance check for isinstance() as registering delete rules or
+        calling a cls method in __new__ seems to change the cls so vanilla
+        isinstance() fails"""
+        is_instance = super(DocumentMetaclass, cls).__instancecheck__(inst)
+        if hasattr(cls, '_meta') and 'delete_rules' in cls._meta and not is_instance:
+            try:
+                is_instance = get_document(cls.__name__) == get_document(inst.__class__.__name__)
+            except NotRegistered:
+                pass
+        return is_instance
+
     @classmethod
     def _unique_with_indexes(cls, new_class, namespace=""):
         unique_indexes = []
diff --git a/tests/document.py b/tests/document.py
index 391c3e25..a4f09929 100644
--- a/tests/document.py
+++ b/tests/document.py
@@ -2245,6 +2245,8 @@ class DocumentTest(unittest.TestCase):
         author.delete()
         self.assertEqual(len(BlogPost.objects), 0)
 
+    def test_invalid_reverse_delete_rules_raise_errors(self):
+
         def throw_invalid_document_error():
             class Blog(Document):
                 content = StringField()
@@ -2253,6 +2255,12 @@ class DocumentTest(unittest.TestCase):
 
         self.assertRaises(InvalidDocumentError, throw_invalid_document_error)
 
+        def throw_invalid_document_error_embedded():
+            class Parents(EmbeddedDocument):
+                father = ReferenceField('Person', reverse_delete_rule=DENY)
+                mother = ReferenceField('Person', reverse_delete_rule=DENY)
+
+        self.assertRaises(InvalidDocumentError, throw_invalid_document_error_embedded)
 
     def test_reverse_delete_rule_cascade_recurs(self):
         """Ensure that a chain of documents is also deleted upon cascaded