[Python-3000-checkins] r65611 - in python/branches/py3k: Doc/library/csv.rst Lib/csv.py Lib/test/test_csv.py

[skip.montanaro]

Author: skip.montanaro
Date: Sat Aug 9 21:44:22 2008
New Revision: 65611

Log:
Merged revisions 65605 via svnmerge from
svn+ssh://pythondev at svn.python.org/python/trunk

........
r65605 | skip.montanaro | 2008-08-08 17:52:51 -0500 (Fri, 08 Aug 2008) | 1 line

accept issue 3436
........


Modified:
python/branches/py3k/Doc/library/csv.rst
python/branches/py3k/Lib/csv.py
python/branches/py3k/Lib/test/test_csv.py

Modified: python/branches/py3k/Doc/library/csv.rst
==============================================================================
--- python/branches/py3k/Doc/library/csv.rst (original)
+++ python/branches/py3k/Doc/library/csv.rst Sat Aug 9 21:44:22 2008
@@ -372,6 +372,18 @@



+DictReader objects have the following public attribute:
+
+
+.. attribute:: csvreader.fieldnames
+
+ If not passed as a parameter when creating the object, this attribute is
+ initialized upon first access or when the first record is read from the
+ file.
+
+ .. versionchanged:: 2.6
+
+
Writer Objects
--------------


Modified: python/branches/py3k/Lib/csv.py
==============================================================================
--- python/branches/py3k/Lib/csv.py (original)
+++ python/branches/py3k/Lib/csv.py Sat Aug 9 21:44:22 2008
@@ -68,7 +68,7 @@
class DictReader:
def __init__(self, f, fieldnames=None, restkey=None, restval=None,
dialect="excel", *args, **kwds):
- self.fieldnames = fieldnames # list of keys for the dict
+ self._fieldnames = fieldnames # list of keys for the dict
self.restkey = restkey # key to catch long rows
self.restval = restval # default value for short rows
self.reader = reader(f, dialect, *args, **kwds)
@@ -78,11 +78,25 @@
def __iter__(self):
return self

+ @property
+ def fieldnames(self):
+ if self._fieldnames is None:
+ try:
+ self._fieldnames = next(self.reader)
+ except StopIteration:
+ pass
+ self.line_num = self.reader.line_num
+ return self._fieldnames
+
+ @fieldnames.setter
+ def fieldnames(self, value):
+ self._fieldnames = value
+
def __next__(self):
+ if self.line_num == 0:
+ # Used only for its side effect.
+ self.fieldnames
row = next(self.reader)
- if self.fieldnames is None:
- self.fieldnames = row
- row = next(self.reader)
self.line_num = self.reader.line_num

# unlike the basic reader, we prefer not to return blanks,

Modified: python/branches/py3k/Lib/test/test_csv.py
==============================================================================
--- python/branches/py3k/Lib/test/test_csv.py (original)
+++ python/branches/py3k/Lib/test/test_csv.py Sat Aug 9 21:44:22 2008
@@ -544,6 +544,29 @@
fileobj.seek(0)
reader = csv.DictReader(fileobj)
self.assertEqual(next(reader), {"f1": '1', "f2": '2', "f3": 'abc'})
+ self.assertEqual(reader.fieldnames, ["f1", "f2", "f3"])
+
+ # Two test cases to make sure existing ways of implicitly setting
+ # fieldnames continue to work. Both arise from discussion in issue3436.
+ def test_read_dict_fieldnames_from_file(self):
+ with TemporaryFile("w+") as fileobj:
+ fileobj.write("f1,f2,f3\r\n1,2,abc\r\n")
+ fileobj.seek(0)
+ reader = csv.DictReader(fileobj,
+ fieldnames=next(csv.reader(fileobj)))
+ self.assertEqual(reader.fieldnames, ["f1", "f2", "f3"])
+ self.assertEqual(next(reader), {"f1": '1', "f2": '2', "f3": 'abc'})
+
+ def test_read_dict_fieldnames_chain(self):
+ import itertools
+ with TemporaryFile("w+") as fileobj:
+ fileobj.write("f1,f2,f3\r\n1,2,abc\r\n")
+ fileobj.seek(0)
+ reader = csv.DictReader(fileobj)
+ first = next(reader)
+ for row in itertools.chain([first], reader):
+ self.assertEqual(reader.fieldnames, ["f1", "f2", "f3"])
+ self.assertEqual(row, {"f1": '1', "f2": '2', "f3": 'abc'})

def test_read_long(self):
with TemporaryFile("w+") as fileobj:
@@ -568,6 +591,7 @@
fileobj.write("f1,f2\r\n1,2,abc,4,5,6\r\n")
fileobj.seek(0)
reader = csv.DictReader(fileobj, restkey="_rest")
+ self.assertEqual(reader.fieldnames, ["f1", "f2"])
self.assertEqual(next(reader), {"f1": '1', "f2": '2',
"_rest": ["abc", "4", "5", "6"]})