Added delete method to QuerySet

mongoengine/collection.py

@@ -8,10 +8,40 @@ class QuerySet(object):
     providing Document objects as the results.
     """
     
-    def __init__(self, document, cursor):
+    def __init__(self, document, collection, query):
         self._document = document
-        self._cursor = cursor
+        self._collection = collection
+
+        self._query = QuerySet._transform_query(**query)
+        self._query['_types'] = self._document._class_name
+        self._cursor_obj = None
+
+    @property
+    def _cursor(self):
+        if not self._cursor_obj:
+            self._cursor_obj = self._collection.find(self._query)
+        return self._cursor_obj
        
+    @classmethod
+    def _transform_query(cls, **query):
+        """Transform a query from Django-style format to Mongo format.
+        """
+        operators = ['neq', 'gt', 'gte', 'lt', 'lte', 'in', 'nin', 'mod',
+                     'all', 'size', 'exists']
+
+        mongo_query = {}
+        for key, value in query.items():
+            parts = key.split('__')
+            # Check for an operator and transform to mongo-style if there is
+            if parts[-1] in operators:
+                op = parts.pop()
+                value = {'$' + op: value}
+
+            key = '.'.join(parts)
+            mongo_query[key] = value
+
+        return mongo_query
+
     def next(self):
         """Wrap the result in a Document object.
         """
@@ -35,6 +65,11 @@ class QuerySet(object):
         self._cursor.skip(n)
         return self
 
+    def delete(self):
+        """Delete the documents matched by the query.
+        """
+        self._collection.remove(self._query)
+
     def __iter__(self):
         return self
 
@@ -56,31 +91,10 @@ class CollectionManager(object):
         _id = self._collection.save(document._to_mongo())
         document._id = _id
 
-    def _transform_query(self, **query):
-        """Transform a query from Django-style format to Mongo format.
-        """
-        operators = ['neq', 'gt', 'gte', 'lt', 'lte', 'in', 'nin', 'mod',
-                     'all', 'size', 'exists']
-
-        mongo_query = {}
-        for key, value in query.items():
-            parts = key.split('__')
-            # Check for an operator and transform to mongo-style if there is
-            if parts[-1] in operators:
-                op = parts.pop()
-                value = {'$' + op: value}
-
-            key = '.'.join(parts)
-            mongo_query[key] = value
-
-        return mongo_query
-
     def find(self, **query):
         """Query the collection for documents matching the provided query.
         """
-        query = self._transform_query(**query)
-        query['_types'] = self._document._class_name
-        return QuerySet(self._document, self._collection.find(query))
+        return QuerySet(self._document, self._collection, query)
 
     def find_one(self, object_id=None, **query):
         """Query the collection for document matching the provided query.
@@ -92,7 +106,7 @@ class CollectionManager(object):
             query = object_id
         else:
             # Otherwise, use the query provided
-            query = self._transform_query(**query)
+            query = QuerySet._transform_query(**query)
             query['_types'] = self._document._class_name
 
         result = self._collection.find_one(query)

tests/collection.py

@@ -1,7 +1,7 @@
 import unittest
 import pymongo
 
-from mongoengine.collection import CollectionManager
+from mongoengine.collection import CollectionManager, QuerySet
 from mongoengine.connection import _get_db
 from mongoengine import *
 
@@ -31,14 +31,13 @@ class CollectionManagerTest(unittest.TestCase):
     def test_transform_query(self):
         """Ensure that the _transform_query function operates correctly.
         """
-        manager = self.Person().objects
-        self.assertEqual(manager._transform_query(name='test', age=30),
+        self.assertEqual(QuerySet._transform_query(name='test', age=30),
                          {'name': 'test', 'age': 30})
-        self.assertEqual(manager._transform_query(age__lt=30), 
+        self.assertEqual(QuerySet._transform_query(age__lt=30), 
                          {'age': {'$lt': 30}})
-        self.assertEqual(manager._transform_query(friend__age__gte=30), 
+        self.assertEqual(QuerySet._transform_query(friend__age__gte=30), 
                          {'friend.age': {'$gte': 30}})
-        self.assertEqual(manager._transform_query(name__exists=True), 
+        self.assertEqual(QuerySet._transform_query(name__exists=True), 
                          {'name': {'$exists': True}})
 
     def test_find(self):
@@ -125,6 +124,21 @@ class CollectionManagerTest(unittest.TestCase):
         
         self.db.drop_collection(BlogPost._meta['collection'])
 
+    def test_delete(self):
+        """Ensure that documents are properly deleted from the database.
+        """
+        self.Person(name="User A", age=20).save()
+        self.Person(name="User B", age=30).save()
+        self.Person(name="User C", age=40).save()
+
+        self.assertEqual(self.Person.objects.find().count(), 3)
+
+        self.Person.objects.find(age__lt=30).delete()
+        self.assertEqual(self.Person.objects.find().count(), 2)
+
+        self.Person.objects.find().delete()
+        self.assertEqual(self.Person.objects.find().count(), 0)
+
 
 if __name__ == '__main__':
     unittest.main()

tests/document.py

@@ -1,4 +1,5 @@
 import unittest
+import pymongo
 
 from mongoengine import *
 from mongoengine.connection import _get_db
@@ -246,13 +247,19 @@ class DocumentTest(unittest.TestCase):
         author.save()
 
         post = BlogPost(content='Watched some TV today... how exciting.')
+        # Should only reference author when saving
         post.author = author
         post.save()
 
         post_obj = BlogPost.objects.find_one()
+
+        # Test laziness
+        self.assertTrue(isinstance(post_obj._data['author'], 
+                                   pymongo.dbref.DBRef))
         self.assertTrue(isinstance(post_obj.author, self.Person))
         self.assertEqual(post_obj.author.name, 'Test User')
 
+        # Ensure that the dereferenced object may be changed and saved
         post_obj.author.age = 25
         post_obj.author.save()