get_error_detail: use error_list to get code(s)

Upstream PR: encode#5785

rest_framework/fields.py

@@ -236,8 +236,9 @@ def get_error_detail(exc_info):
     """
     code = getattr(exc_info, 'code', None) or 'invalid'
     return [
-        ErrorDetail(msg, code=code)
-        for msg in exc_info.messages
+        ErrorDetail(error.message % (error.params or ()),
+                    code=error.code if error.code else code)
+        for error in exc_info.error_list
     ]
 
 

tests/test_fields.py

@@ -6,6 +6,7 @@
 from decimal import ROUND_DOWN, ROUND_UP, Decimal
 
 import pytest
+from django.core.exceptions import ValidationError as DjangoValidationError
 from django.http import QueryDict
 from django.test import TestCase, override_settings
 from django.utils import six
@@ -2108,3 +2109,22 @@ class ExampleSerializer(serializers.Serializer):
             "'ExampleSerializer', because it is the same as the default "
             "method name. Remove the `method_name` argument."
         )
+
+
+class TestValidationErrorCode:
+    @pytest.mark.parametrize('use_list', (False, True))
+    def test_validationerror_code(self, use_list):
+
+        class ExampleSerializer(serializers.Serializer):
+            password = serializers.CharField()
+
+            def validate_password(self, obj):
+                err = DjangoValidationError('exc_msg', code='exc_code')
+                if use_list:
+                    err = DjangoValidationError([err])
+                raise err
+
+        serializer = ExampleSerializer(data={'password': 123})
+        serializer.is_valid()
+        assert serializer.errors == {'password': ['exc_msg']}
+        assert serializer.errors['password'][0].code == 'exc_code'