From a3e0fbd606eec9319d980dc618fbf4d17e22f508 Mon Sep 17 00:00:00 2001
From: Emmanuel Leblond <emmanuel.leblond@gmail.com>
Date: Wed, 15 Jul 2015 11:15:40 +0200
Subject: [PATCH 1/3] Add SaveConditionError exception

---
 mongoengine/document.py | 7 ++++---
 mongoengine/errors.py   | 4 ++++
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/mongoengine/document.py b/mongoengine/document.py
index c5498750..70abadcc 100644
--- a/mongoengine/document.py
+++ b/mongoengine/document.py
@@ -16,7 +16,8 @@ from mongoengine.base import (
     ALLOW_INHERITANCE,
     get_document
 )
-from mongoengine.errors import InvalidQueryError, InvalidDocumentError
+from mongoengine.errors import (InvalidQueryError, InvalidDocumentError,
+                                SaveConditionError)
 from mongoengine.python_support import IS_PYMONGO_3
 from mongoengine.queryset import (OperationError, NotUniqueError,
                                   QuerySet, transform)
@@ -359,8 +360,8 @@ class Document(BaseDocument):
                     last_error = collection.update(select_dict, update_query,
                                                    upsert=upsert, **write_concern)
                     if not upsert and last_error['nModified'] == 0:
-                        raise OperationError('Race condition preventing'
-                                             ' document update detected')
+                        raise SaveConditionError('Race condition preventing'
+                                                 ' document update detected')
                     created = is_new_object(last_error)
 
             if cascade is None:
diff --git a/mongoengine/errors.py b/mongoengine/errors.py
index b7fb7632..2c5c2946 100644
--- a/mongoengine/errors.py
+++ b/mongoengine/errors.py
@@ -41,6 +41,10 @@ class NotUniqueError(OperationError):
     pass
 
 
+class SaveConditionError(OperationError):
+    pass
+
+
 class FieldDoesNotExist(Exception):
     """Raised when trying to set a field
     not declared in a :class:`~mongoengine.Document`

From 3ffaf2c0e12ab59940baa1bec3f072b7133f1e4f Mon Sep 17 00:00:00 2001
From: Emmanuel Leblond <emmanuel.leblond@gmail.com>
Date: Wed, 15 Jul 2015 11:59:29 +0200
Subject: [PATCH 2/3] Correct SaveConditionError involved tests

---
 tests/document/instance.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tests/document/instance.py b/tests/document/instance.py
index ea7d5668..7a393416 100644
--- a/tests/document/instance.py
+++ b/tests/document/instance.py
@@ -17,7 +17,7 @@ from tests.fixtures import (PickleEmbedded, PickleTest, PickleSignalsTest,
 from mongoengine import *
 from mongoengine.errors import (NotRegistered, InvalidDocumentError,
                                 InvalidQueryError, NotUniqueError,
-                                FieldDoesNotExist)
+                                FieldDoesNotExist, SaveConditionError)
 from mongoengine.queryset import NULLIFY, Q
 from mongoengine.connection import get_db
 from mongoengine.base import get_document
@@ -1021,7 +1021,7 @@ class InstanceTest(unittest.TestCase):
         flip(w1)
         self.assertTrue(w1.toggle)
         self.assertEqual(w1.count, 1)
-        self.assertRaises(OperationError,
+        self.assertRaises(SaveConditionError,
             w1.save, save_condition={'save_id': UUID(42)})
         w1.reload()
         self.assertFalse(w1.toggle)
@@ -1050,7 +1050,7 @@ class InstanceTest(unittest.TestCase):
         self.assertEqual(w1.count, 2)
         flip(w2)
         flip(w2)
-        self.assertRaises(OperationError,
+        self.assertRaises(SaveConditionError,
             w2.save, save_condition={'save_id': old_id})
         w2.reload()
         self.assertFalse(w2.toggle)
@@ -1063,7 +1063,7 @@ class InstanceTest(unittest.TestCase):
         self.assertTrue(w1.toggle)
         self.assertEqual(w1.count, 3)
         flip(w1)
-        self.assertRaises(OperationError,
+        self.assertRaises(SaveConditionError,
             w1.save, save_condition={'count__gte': w1.count})
         w1.reload()
         self.assertTrue(w1.toggle)

From 0752c6b24f163cdfd763609e620dff2c31661294 Mon Sep 17 00:00:00 2001
From: Emmanuel Leblond <emmanuel.leblond@gmail.com>
Date: Sun, 19 Jul 2015 10:33:54 +0200
Subject: [PATCH 3/3] Update changelog for #1070

---
 docs/changelog.rst      | 1 +
 mongoengine/document.py | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/docs/changelog.rst b/docs/changelog.rst
index c512eca0..4334ae5a 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -7,6 +7,7 @@ Changes in 0.10.1 - DEV
 - Fix infinite recursion with CASCADE delete rules under specific conditions. #1046
 - Fix CachedReferenceField bug when loading cached docs as DBRef but failing to save them. #1047
 - Fix ignored chained options #842
+- Document save's save_condition error raises `SaveConditionError` exception #1070
 
 Changes in 0.10.0
 =================
diff --git a/mongoengine/document.py b/mongoengine/document.py
index 70abadcc..d68d6d65 100644
--- a/mongoengine/document.py
+++ b/mongoengine/document.py
@@ -295,6 +295,8 @@ class Document(BaseDocument):
             if the condition is satisfied in the current db record.
         .. versionchanged:: 0.10
             :class:`OperationError` exception raised if save_condition fails.
+        .. versionchanged:: 0.10.1
+            :class: save_condition failure now raises a `SaveConditionError`
         """
         signals.pre_save.send(self.__class__, document=self)