Added update() convenience method to a document

Thanks to @dcrosta for the initial code
[closes #229]

mongoengine/document.py

@@ -193,6 +193,18 @@ class Document(BaseDocument):
         reset_changed_fields(self)
         signals.post_save.send(self.__class__, document=self, created=created)
 
+    def update(self, **kwargs):
+        """Performs an update on the :class:`~mongoengine.Document`
+        A convenience wrapper to :meth:`~mongoengine.QuerySet.update`.
+
+        Raises :class:`OperationError` if called on an object that has not yet
+        been saved.
+        """
+        if not self.pk:
+            raise OperationError('attempt to update a document not yet saved')
+
+        return self.__class__.objects(pk=self.pk).update_one(**kwargs)
+
     def delete(self, safe=False):
         """Delete the :class:`~mongoengine.Document` from the database. This
         will only take effect if the document has been previously saved.

tests/document.py

@@ -1203,6 +1203,29 @@ class DocumentTest(unittest.TestCase):
         self.assertEqual(person.name, None)
         self.assertEqual(person.age, None)
 
+    def test_document_update(self):
+
+        def update_not_saved_raises():
+            person = self.Person(name='dcrosta')
+            person.update(set__name='Dan Crosta')
+
+        self.assertRaises(OperationError, update_not_saved_raises)
+
+        author = self.Person(name='dcrosta')
+        author.save()
+
+        author.update(set__name='Dan Crosta')
+        author.reload()
+
+        p1 = self.Person.objects.first()
+        self.assertEquals(p1.name, author.name)
+
+        def update_no_value_raises():
+            person = self.Person.objects.first()
+            person.update()
+
+        self.assertRaises(OperationError, update_no_value_raises)
+
     def test_embedded_update(self):
         """
         Test update on `EmbeddedDocumentField` fields

tests/queryset.py

@@ -242,7 +242,7 @@ class QuerySetTest(unittest.TestCase):
             self.Person.objects(pk=author.pk).update({})
 
         def update_one_raises():
-            self.Person.objects(pk=author.pk).update({})
+            self.Person.objects(pk=author.pk).update_one({})
 
         self.assertRaises(OperationError, update_raises)
         self.assertRaises(OperationError, update_one_raises)