From edff514db1e42eff1e1a83a86998c0bccbc5fd11 Mon Sep 17 00:00:00 2001
From: Tim Klein <timjklein36@gmail.com>
Date: Fri, 12 Feb 2021 14:51:33 -0500
Subject: [PATCH] Retain the order of multiple dictionary items added via Delta

- This alters the data structure used to determine dictionary
  items added (via storing the keys from `t1` and `t2` in
  OrderedSet objects)
- This also adds a unit test to verify that after applying a
  Delta with multiple dict items added, the added keys are not
  sorted, but are instead added to the resulting dictionary
  in the same insertion order as their source object (`t2`)
---
 deepdiff/delta.py   | 15 +++++++++++----
 deepdiff/diff.py    | 12 ++++++------
 tests/test_delta.py | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 52 insertions(+), 10 deletions(-)

diff --git a/deepdiff/delta.py b/deepdiff/delta.py
index 81e34e7c..9e6fd78c 100644
--- a/deepdiff/delta.py
+++ b/deepdiff/delta.py
@@ -267,16 +267,23 @@ def _do_iterable_item_added(self):
     def _do_dictionary_item_added(self):
         dictionary_item_added = self.diff.get('dictionary_item_added')
         if dictionary_item_added:
-            self._do_item_added(dictionary_item_added)
+            self._do_item_added(dictionary_item_added, sort=False)
 
     def _do_attribute_added(self):
         attribute_added = self.diff.get('attribute_added')
         if attribute_added:
             self._do_item_added(attribute_added)
 
-    def _do_item_added(self, items):
-        # sorting the items by their path so that the items with smaller index are applied first.
-        for path, new_value in sorted(items.items(), key=lambda x: x[0]):
+    def _do_item_added(self, items, sort=True):
+        if sort:
+            # sorting items by their path so that the items with smaller index
+            # are applied first (unless `sort` is `False` so that order of
+            # added items is retained, e.g. for dicts).
+            items = sorted(items.items(), key=lambda x: x[0])
+        else:
+            items = items.items()
+
+        for path, new_value in items:
             elem_and_details = self._get_elements_and_details(path)
             if elem_and_details:
                 elements, parent, parent_to_obj_elem, parent_to_obj_action, obj, elem, action = elem_and_details
diff --git a/deepdiff/diff.py b/deepdiff/diff.py
index 133661b8..e3eb1e68 100755
--- a/deepdiff/diff.py
+++ b/deepdiff/diff.py
@@ -450,16 +450,16 @@ def _diff_dict(self,
             rel_class = DictRelationship
 
         if self.ignore_private_variables:
-            t1_keys = {key for key in t1 if not(isinstance(key, str) and key.startswith('__'))}
-            t2_keys = {key for key in t2 if not(isinstance(key, str) and key.startswith('__'))}
+            t1_keys = OrderedSet([key for key in t1 if not(isinstance(key, str) and key.startswith('__'))])
+            t2_keys = OrderedSet([key for key in t2 if not(isinstance(key, str) and key.startswith('__'))])
         else:
-            t1_keys = set(t1.keys())
-            t2_keys = set(t2.keys())
+            t1_keys = OrderedSet(t1.keys())
+            t2_keys = OrderedSet(t2.keys())
         if self.ignore_string_type_changes or self.ignore_numeric_type_changes:
             t1_clean_to_keys = self._get_clean_to_keys_mapping(keys=t1_keys, level=level)
             t2_clean_to_keys = self._get_clean_to_keys_mapping(keys=t2_keys, level=level)
-            t1_keys = set(t1_clean_to_keys.keys())
-            t2_keys = set(t2_clean_to_keys.keys())
+            t1_keys = OrderedSet(t1_clean_to_keys.keys())
+            t2_keys = OrderedSet(t2_clean_to_keys.keys())
         else:
             t1_clean_to_keys = t2_clean_to_keys = None
 
diff --git a/tests/test_delta.py b/tests/test_delta.py
index e91a6463..af5051f9 100644
--- a/tests/test_delta.py
+++ b/tests/test_delta.py
@@ -335,6 +335,41 @@ def test_list_difference_delta_raises_error_if_prev_value_changed(self):
         delta2 = Delta(diff, verify_symmetry=False, raise_errors=True)
         assert t1 + delta2 == t2
 
+    def test_delta_dict_items_added_retain_order(self):
+        t1 = {
+            6: 6
+        }
+
+        t2 = {
+            6: 6,
+            7: 7,
+            3: 3,
+            5: 5,
+            2: 2,
+            4: 4
+        }
+
+        expected_delta_dict = {
+            'dictionary_item_added': {
+                'root[7]': 7,
+                'root[3]': 3,
+                'root[5]': 5,
+                'root[2]': 2,
+                'root[4]': 4
+            }
+        }
+
+        diff = DeepDiff(t1, t2)
+        delta_dict = diff._to_delta_dict()
+        assert expected_delta_dict == delta_dict
+        delta = Delta(diff, verify_symmetry=False, raise_errors=True)
+
+        result = t1 + delta
+        assert result == t2
+
+        assert list(result.keys()) == [6, 7, 3, 5, 2, 4]
+        assert list(result.keys()) == list(t2.keys())
+
 
 picklalbe_obj_without_item = PicklableClass(11)
 del picklalbe_obj_without_item.item