From 2647ee7e639553dabaaf2cd13b63958b0cd82a93 Mon Sep 17 00:00:00 2001
From: linchiwei123 <306741005@qq.com>
Date: Fri, 28 Jun 2019 14:29:38 +0800
Subject: [PATCH 1/2] =?UTF-8?q?=C2=96=C2=96make=20use=20of=20collections.C?=
 =?UTF-8?q?hainMap=20to=20simplify=20the=20code?=
MIME-Version: 1.0
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---
 django/db/models/query_utils.py | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/django/db/models/query_utils.py b/django/db/models/query_utils.py
index 90289d0da232..0eb8a51c640f 100644
--- a/django/db/models/query_utils.py
+++ b/django/db/models/query_utils.py
@@ -8,7 +8,7 @@
 import copy
 import functools
 import inspect
-from collections import namedtuple
+from collections import ChainMap, namedtuple
 
 from django.db.models.constants import LOOKUP_SEP
 from django.utils import tree
@@ -187,10 +187,7 @@ def merge_dicts(dicts):
         Merge dicts in reverse to preference the order of the original list. e.g.,
         merge_dicts([a, b]) will preference the keys in 'a' over those in 'b'.
         """
-        merged = {}
-        for d in reversed(dicts):
-            merged.update(d)
-        return merged
+        return dict(ChainMap(*dicts))
 
     @classmethod
     def _clear_cached_lookups(cls):

From b532f1300694ae344bf8bc10b5a36124a6b10987 Mon Sep 17 00:00:00 2001
From: linchiwei123 <306741005@qq.com>
Date: Fri, 28 Jun 2019 16:38:12 +0800
Subject: [PATCH 2/2] use ChainMap() instead of dict(ChainMap())

---
 django/db/models/query_utils.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/django/db/models/query_utils.py b/django/db/models/query_utils.py
index 0eb8a51c640f..4966e2ce12d4 100644
--- a/django/db/models/query_utils.py
+++ b/django/db/models/query_utils.py
@@ -187,7 +187,7 @@ def merge_dicts(dicts):
         Merge dicts in reverse to preference the order of the original list. e.g.,
         merge_dicts([a, b]) will preference the keys in 'a' over those in 'b'.
         """
-        return dict(ChainMap(*dicts))
+        return ChainMap(*dicts)
 
     @classmethod
     def _clear_cached_lookups(cls):