added CachedReferenceField restriction to use in EmbeddedDocument

mongoengine/base/metaclasses.py

@@ -16,6 +16,7 @@ __all__ = ('DocumentMetaclass', 'TopLevelDocumentMetaclass')
 
 
 class DocumentMetaclass(type):
+
     """Metaclass for all documents.
     """
 
@@ -141,7 +142,8 @@ class DocumentMetaclass(type):
                 base._subclasses += (_cls,)
             base._types = base._subclasses   # TODO depreciate _types
 
-        Document, EmbeddedDocument, DictField = cls._import_classes()
+        (Document, EmbeddedDocument, DictField,
+         CachedReferenceField) = cls._import_classes()
 
         if issubclass(new_class, Document):
             new_class._collection = None
@@ -170,6 +172,10 @@ class DocumentMetaclass(type):
             f = field
             f.owner_document = new_class
             delete_rule = getattr(f, 'reverse_delete_rule', DO_NOTHING)
+            if isinstance(f, CachedReferenceField) and issubclass(
+                    new_class, EmbeddedDocument):
+                raise InvalidDocumentError(
+                    "CachedReferenceFields is not allowed in EmbeddedDocuments")
             if isinstance(f, ComplexBaseField) and hasattr(f, 'field'):
                 delete_rule = getattr(f.field,
                                       'reverse_delete_rule',
@@ -224,10 +230,12 @@ class DocumentMetaclass(type):
         Document = _import_class('Document')
         EmbeddedDocument = _import_class('EmbeddedDocument')
         DictField = _import_class('DictField')
-        return (Document, EmbeddedDocument, DictField)
+        CachedReferenceField = _import_class('CachedReferenceField')
+        return (Document, EmbeddedDocument, DictField, CachedReferenceField)
 
 
 class TopLevelDocumentMetaclass(DocumentMetaclass):
+
     """Metaclass for top-level documents (i.e. documents that have their own
     collection in the database.
     """
@@ -387,6 +395,7 @@ class TopLevelDocumentMetaclass(DocumentMetaclass):
 
 
 class MetaDict(dict):
+
     """Custom dictionary for meta classes.
     Handles the merging of set indexes
     """
@@ -401,5 +410,6 @@ class MetaDict(dict):
 
 
 class BasesTuple(tuple):
+
     """Special class to handle introspection of bases tuple in __new__"""
     pass

mongoengine/common.py

@@ -25,6 +25,7 @@ def _import_class(cls_name):
                      'GenericEmbeddedDocumentField', 'GeoPointField',
                      'PointField', 'LineStringField', 'ListField',
                      'PolygonField', 'ReferenceField', 'StringField',
+                     'CachedReferenceField',
                      'ComplexBaseField', 'GeoJsonBaseField')
     queryset_classes = ('OperationError',)
     deref_classes = ('DeReference',)

tests/fields/fields.py

@@ -1539,6 +1539,18 @@ class FieldTest(unittest.TestCase):
         self.assertEqual(ocorrence.person, "teste")
         self.assertTrue(isinstance(ocorrence.animal, Animal))
 
+    def test_cached_reference_fields_on_embedded_documents(self):
+        def build():
+            class Test(Document):
+                name = StringField()
+
+            type('WrongEmbeddedDocument', (
+                EmbeddedDocument,), {
+                    'test': CachedReferenceField(Test)
+            })
+
+        self.assertRaises(InvalidDocumentError, build)
+
     def test_cached_reference_embedded_fields(self):
         class Owner(EmbeddedDocument):
             TPS = (