From 290b821a3ae2e130192a90bb62ad5ae8d5461005 Mon Sep 17 00:00:00 2001
From: Erdenezul <erdenezul@shine.mn>
Date: Sat, 2 Sep 2017 02:05:27 +0900
Subject: [PATCH] add fix for reload(fields) affect changed fields #1371

---
 mongoengine/document.py    |  5 +++--
 tests/document/instance.py | 20 +++++++++++++++++++-
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/mongoengine/document.py b/mongoengine/document.py
index 2de0b1a3..182733c7 100644
--- a/mongoengine/document.py
+++ b/mongoengine/document.py
@@ -705,7 +705,6 @@ class Document(BaseDocument):
             obj = obj[0]
         else:
             raise self.DoesNotExist('Document does not exist')
-
         for field in obj._data:
             if not fields or field in fields:
                 try:
@@ -721,7 +720,9 @@ class Document(BaseDocument):
                         # i.e. obj.update(unset__field=1) followed by obj.reload()
                         delattr(self, field)
 
-        self._changed_fields = obj._changed_fields
+        self._changed_fields = list(
+            set(self._changed_fields) - set(fields)
+            ) if fields else obj._changed_fields
         self._created = False
         return self
 
diff --git a/tests/document/instance.py b/tests/document/instance.py
index 38c7fcaf..b255e8a6 100644
--- a/tests/document/instance.py
+++ b/tests/document/instance.py
@@ -476,6 +476,24 @@ class InstanceTest(unittest.TestCase):
         doc.save()
         doc.reload()
 
+    def test_reload_with_changed_fields(self):
+        """Ensures reloading will not affect changed fields"""
+        class User(Document):
+            name = StringField()
+            number = IntField()
+        User.drop_collection()
+
+        user = User(name="Bob", number=1).save()
+        user.name = "John"
+        user.number = 2
+
+        self.assertEqual(user._get_changed_fields(), ['name', 'number'])
+        user.reload('number')
+        self.assertEqual(user._get_changed_fields(), ['name'])
+        user.save()
+        user.reload()
+        self.assertEqual(user.name, "John")
+
     def test_reload_referencing(self):
         """Ensures reloading updates weakrefs correctly."""
         class Embedded(EmbeddedDocument):
@@ -521,7 +539,7 @@ class InstanceTest(unittest.TestCase):
         doc.save()
         doc.dict_field['extra'] = 1
         doc = doc.reload(10, 'list_field')
-        self.assertEqual(doc._get_changed_fields(), [])
+        self.assertEqual(doc._get_changed_fields(), ['dict_field.extra'])
         self.assertEqual(len(doc.list_field), 5)
         self.assertEqual(len(doc.dict_field), 3)
         self.assertEqual(len(doc.embedded_field.list_field), 4)