Issue #27842: The csv.DictReader now returns rows of type OrderedDict.

2 files changed, 18 insertions, 1 deletions

diff --git a/Lib/csv.py b/Lib/csv.py
index 90461db..2e2303a 100644
--- a/Lib/csv.py
+++ b/Lib/csv.py
@@ -11,6 +11,7 @@ from _csv import Error, __version__, writer, reader, register_dialect, \
                  __doc__
 from _csv import Dialect as _Dialect
 
+from collections import OrderedDict
 from io import StringIO
 
 __all__ = ["QUOTE_MINIMAL", "QUOTE_ALL", "QUOTE_NONNUMERIC", "QUOTE_NONE",
@@ -116,7 +117,7 @@ class DictReader:
         # values
         while row == []:
             row = next(self.reader)
-        d = dict(zip(self.fieldnames, row))
+        d = OrderedDict(zip(self.fieldnames, row))
         lf = len(self.fieldnames)
         lr = len(row)
         if lf < lr:
diff --git a/Lib/test/test_csv.py b/Lib/test/test_csv.py
index e97c9f3..9df4080 100644
--- a/Lib/test/test_csv.py
+++ b/Lib/test/test_csv.py
@@ -10,6 +10,7 @@ import csv
 import gc
 import pickle
 from test import support
+from itertools import permutations
 
 class Test_Csv(unittest.TestCase):
     """
@@ -1092,6 +1093,21 @@ class TestUnicode(unittest.TestCase):
             fileobj.seek(0)
             self.assertEqual(fileobj.read(), expected)
 
+class KeyOrderingTest(unittest.TestCase):
+
+    def test_ordering_for_the_dict_reader_and_writer(self):
+        resultset = set()
+        for keys in permutations("abcde"):
+            with TemporaryFile('w+', newline='', encoding="utf-8") as fileobject:
+                dw = csv.DictWriter(fileobject, keys)
+                dw.writeheader()
+                fileobject.seek(0)
+                dr = csv.DictReader(fileobject)
+                kt = tuple(dr.fieldnames)
+                self.assertEqual(keys, kt)
+                resultset.add(kt)
+        # Final sanity check: were all permutations unique?
+        self.assertEqual(len(resultset), 120, "Key ordering: some key permutations not collected (expected 120)")
 
 class MiscTestCase(unittest.TestCase):
     def test__all__(self):