From 2aab63d7a56267ffe546c6ee5d18226cbeded997 Mon Sep 17 00:00:00 2001
From: Anton Chasnyk <anton.chasnyk@gmail.com>
Date: Wed, 11 Aug 2021 10:33:07 +0300
Subject: [PATCH] impruved code ValidationError compatible with Django (#8077)

---
 rest_framework/exceptions.py   | 19 ++++++-------------
 tests/test_validation_error.py |  9 ++++++++-
 2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/rest_framework/exceptions.py b/rest_framework/exceptions.py
index 98ca49e9f..0870baa54 100644
--- a/rest_framework/exceptions.py
+++ b/rest_framework/exceptions.py
@@ -141,29 +141,22 @@ class ValidationError(APIException):
     status_code = status.HTTP_400_BAD_REQUEST
     default_detail = _('Invalid input.')
     default_code = 'invalid'
+    default_params = {}
 
     def __init__(self, detail=None, code=None, params=None):
         if detail is None:
             detail = self.default_detail
         if code is None:
             code = self.default_code
+        if params is None:
+            params = self.default_params
 
         # For validation failures, we may collect many errors together,
         # so the details should always be coerced to a list if not already.
-        if isinstance(detail, tuple):
-            detail_list = list()
-            if params is not None:
-                for msg in detail:
-                    detail_list.append(msg % params)
-                detail = detail_list
-            else:
-                detail = list(detail)
-        elif not isinstance(detail, dict) and not isinstance(detail, list):
-            if params is not None:
+        if isinstance(detail, tuple) or isinstance(detail, list):
+                detail = [msg % params for msg in detail]
+        elif not isinstance(detail, dict):
                 detail = [detail % params]
-            else:
-                detail = [detail]
-
         self.detail = _get_error_details(detail, code)
 
 
diff --git a/tests/test_validation_error.py b/tests/test_validation_error.py
index 537506771..0453e362d 100644
--- a/tests/test_validation_error.py
+++ b/tests/test_validation_error.py
@@ -121,4 +121,11 @@ class TestvalidationErrorWithDjangoStyle(TestCase):
         assert isinstance(error.detail, list)
         assert len(error.detail) == 2
         assert str(error.detail[0]) == 'Invalid value: 42'
-        assert str(error.detail[1]) == 'Invalid value: 43'
\ No newline at end of file
+        assert str(error.detail[1]) == 'Invalid value: 43'
+
+    def test_validation_error_details_list(self):
+        error = ValidationError(detail=['Invalid value: %(value1)s', 'Invalid value: %(value2)s'], params={'value1': '42', 'value2':'43'})
+        assert isinstance(error.detail, list)
+        assert len(error.detail) == 2
+        assert str(error.detail[0]) == 'Invalid value: 42'
+        assert str(error.detail[1]) == 'Invalid value: 43'