From 0462f186807a4b710f3e35e063048e1bad9a9cb7 Mon Sep 17 00:00:00 2001
From: Bob Cribbs <bcribbs@zehnergroup.com>
Date: Tue, 19 Aug 2014 21:29:13 +0300
Subject: [PATCH] Allow atomic update for the entire `DictField`

---
 AUTHORS                |  1 +
 mongoengine/fields.py  |  4 ++++
 tests/fields/fields.py | 25 +++++++++++++++++++++++++
 3 files changed, 30 insertions(+)

diff --git a/AUTHORS b/AUTHORS
index 81ec2f76..326caec6 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -206,3 +206,4 @@ that much better:
  * Clay McClure (https://github.com/claymation)
  * Bruno Rocha (https://github.com/rochacbruno)
  * Norberto Leite (https://github.com/nleite)
+ * Bob Cribbs (https://github.com/bocribbz)
diff --git a/mongoengine/fields.py b/mongoengine/fields.py
index 7bbc221a..8b3cf4c7 100644
--- a/mongoengine/fields.py
+++ b/mongoengine/fields.py
@@ -826,6 +826,10 @@ class DictField(ComplexBaseField):
             return StringField().prepare_query_value(op, value)
 
         if hasattr(self.field, 'field'):
+            if op in ('set', 'unset') and isinstance(value, dict):
+                return dict(
+                    (k, self.field.prepare_query_value(op, v))
+                    for k, v in value.items())
             return self.field.prepare_query_value(op, value)
 
         return super(DictField, self).prepare_query_value(op, value)
diff --git a/tests/fields/fields.py b/tests/fields/fields.py
index 0af22a34..7d906917 100644
--- a/tests/fields/fields.py
+++ b/tests/fields/fields.py
@@ -18,6 +18,7 @@ from bson import Binary, DBRef, ObjectId
 from mongoengine import *
 from mongoengine.connection import get_db
 from mongoengine.base import _document_registry
+from mongoengine.base.datastructures import BaseDict
 from mongoengine.errors import NotRegistered
 from mongoengine.python_support import PY3, b, bin_type
 
@@ -1251,6 +1252,30 @@ class FieldTest(unittest.TestCase):
 
         Simple.drop_collection()
 
+    def test_atomic_update_dict_field(self):
+        """Ensure that the entire DictField can be atomically updated."""
+
+
+        class Simple(Document):
+            mapping = DictField(field=ListField(IntField(required=True)))
+
+        Simple.drop_collection()
+
+        e = Simple()
+        e.mapping['someints'] = [1, 2]
+        e.save()
+        e.update(set__mapping={"ints": [3, 4]})
+        e.reload()
+        self.assertEqual(BaseDict, type(e.mapping))
+        self.assertEqual({"ints": [3, 4]}, e.mapping)
+
+        def create_invalid_mapping():
+            e.update(set__mapping={"somestrings": ["foo", "bar",]})
+
+        self.assertRaises(ValueError, create_invalid_mapping)
+
+        Simple.drop_collection()
+
     def test_mapfield(self):
         """Ensure that the MapField handles the declared type."""