Merge branch 'master' of git://github.com/flosch/mongoengine

Added unit test for get_or_create, merged flosch's get with
punteney's get.

Conflicts:
	mongoengine/queryset.py

mongoengine/base.py

@@ -6,7 +6,6 @@ import pymongo
 class ValidationError(Exception):
     pass
 
-
 class BaseField(object):
     """A base class for fields in a MongoDB document. Instances of this class
     may be added to subclasses of `Document` to define a document's schema.
@@ -76,7 +75,10 @@ class ObjectIdField(BaseField):
 
     def to_mongo(self, value):
         if not isinstance(value, pymongo.objectid.ObjectId):
-            return pymongo.objectid.ObjectId(str(value))
+            try:
+                return pymongo.objectid.ObjectId(str(value))
+            except Exception, e:
+                raise ValidationError(e.message)
         return value
 
     def prepare_query_value(self, value):

mongoengine/fields.py

@@ -209,20 +209,19 @@ class ReferenceField(BaseField):
         return super(ReferenceField, self).__get__(instance, owner)
 
     def to_mongo(self, document):
-        if isinstance(document, (str, unicode, pymongo.objectid.ObjectId)):
-            # document may already be an object id
-            id_ = document
-        else:
+        id_field_name = self.document_type._meta['id_field']
+        id_field = self.document_type._fields[id_field_name]
+
+        if isinstance(document, Document):
             # We need the id from the saved object to create the DBRef
             id_ = document.id
             if id_ is None:
                 raise ValidationError('You can only reference documents once '
                                       'they have been saved to the database')
+        else:
+            id_ = document
 
-        # id may be a string rather than an ObjectID object
-        if not isinstance(id_, pymongo.objectid.ObjectId):
-            id_ = pymongo.objectid.ObjectId(id_)
-
+        id_ = id_field.to_mongo(id_)
         collection = self.document_type._meta['collection']
         return pymongo.dbref.DBRef(collection, id_)
     

mongoengine/queryset.py

@@ -10,6 +10,13 @@ __all__ = ['queryset_manager', 'Q', 'InvalidQueryError',
 # The maximum number of items to display in a QuerySet.__repr__
 REPR_OUTPUT_SIZE = 20
 
+class DoesNotExist(Exception):
+	pass
+
+
+class MultipleObjectsReturned(Exception):
+    pass
+
 
 class InvalidQueryError(Exception):
     pass
@@ -298,18 +305,43 @@ class QuerySet(object):
 
     def get(self, *q_objs, **query):
         """Retrieve the the matching object raising 
-        'MultipleObjectsReturned' or 'DoesNotExist' exceptions
-        if multiple or no results are found.
+        :class:`~mongoengine.queryset.MultipleObjectsReturned` or 
+        :class:`~mongoengine.queryset.DoesNotExist` exceptions if multiple or
+        no results are found.
         """
         self.__call__(*q_objs, **query)
         count = self.count()
         if count == 1:
             return self[0]
         elif count > 1:
-            raise MultipleObjectsReturned
+            message = u'%d items returned, instead of 1' % count
+            raise MultipleObjectsReturned(message)
         else:
-            raise DoesNotExist
+            raise DoesNotExist('Document not found')
 
+    def get_or_create(self, *q_objs, **query):
+        """Retreive unique object or create, if it doesn't exist. Raises
+        :class:`~mongoengine.queryset.MultipleObjectsReturned` if multiple 
+        results are found. A new document will be created if the document 
+        doesn't exists; a dictionary of default values for the new document
+        may be provided as a keyword argument called :attr:`defaults`.
+        """
+        defaults = query.get('defaults', {})
+        if query.has_key('defaults'):
+            del query['defaults']
+        
+        self.__call__(*q_objs, **query)
+        count = self.count()
+        if count == 0:
+            query.update(defaults)
+            doc = self._document(**query)
+            doc.save()
+            return doc
+        elif count == 1:
+            return self.first()
+        else:
+            message = u'%d items returned, instead of 1' % count
+            raise MultipleObjectsReturned(message)
 
     def first(self):
         """Retrieve the first object matching the query.