diff options
| -rw-r--r-- | Doc/library/csv.rst | 10 | ||||
| -rw-r--r-- | Lib/csv.py | 4 | ||||
| -rw-r--r-- | Lib/test/test_csv.py | 4 | ||||
| -rw-r--r-- | Misc/NEWS | 2 |
4 files changed, 20 insertions, 0 deletions
diff --git a/Doc/library/csv.rst b/Doc/library/csv.rst index 510d35a..502d934 100644 --- a/Doc/library/csv.rst +++ b/Doc/library/csv.rst @@ -392,6 +392,16 @@ Writer objects have the following public attribute: A read-only description of the dialect in use by the writer. +DictWriter objects have the following public method: + + +.. method:: DictWriter.writeheader() + + Write a row with the field names (as specified in the constructor). + + .. versionadded:: 2.7 + + .. _csv-examples: Examples @@ -127,6 +127,10 @@ class DictWriter: self.extrasaction = extrasaction self.writer = writer(f, dialect, *args, **kwds) + def writeheader(self): + header = dict(zip(self.fieldnames, self.fieldnames)) + self.writerow(header) + def _dict_to_list(self, rowdict): if self.extrasaction == "raise": wrong_fields = [k for k in rowdict if k not in self.fieldnames] diff --git a/Lib/test/test_csv.py b/Lib/test/test_csv.py index 29e54f7..2c4b783 100644 --- a/Lib/test/test_csv.py +++ b/Lib/test/test_csv.py @@ -535,8 +535,12 @@ class TestDictFields(unittest.TestCase): def test_write_simple_dict(self): with TemporaryFile("w+", newline='') as fileobj: writer = csv.DictWriter(fileobj, fieldnames = ["f1", "f2", "f3"]) + writer.writeheader() + fileobj.seek(0) + self.assertEqual(fileobj.readline(), "f1,f2,f3\r\n") writer.writerow({"f1": 10, "f3": "abc"}) fileobj.seek(0) + fileobj.readline() # header self.assertEqual(fileobj.read(), "10,,abc\r\n") def test_write_no_fields(self): @@ -254,6 +254,8 @@ C-API Library ------- +- Issue #1537721: Add a writeheader() method to csv.DictWriter. + - Issue #7959: ctypes callback functions are now registered correctly with the cylce garbage collector. |