How can I use io.StringIO() with the csv module?

Please use StringIO.StringIO().

http://docs.python.org/library/io.html#io.StringIO

http://docs.python.org/library/stringio.html

io.StringIO is a class. It handles Unicode. It reflects the preferred Python 3 library structure.

StringIO.StringIO is a class. It handles strings. It reflects the legacy Python 2 library structure.

I found this when I tried to serve a CSV file via Flask directly without creating the CSV file on the file system. This works:

import io
import csv

data = [[u'cell one', u'cell two'], [u'cell three', u'cell four']]

output = io.BytesIO()
writer = csv.writer(output, delimiter=',')
writer.writerows(data)
your_csv_string = output.getvalue()

See also

• More about CSV
• The Flask part
• A few notes about Strings / Unicode

The Python 2.7 csv module doesn't support Unicode input: see the note at the beginning of the documentation.

It seems that you'll have to encode the Unicode strings to byte strings, and use io.BytesIO, instead of io.StringIO.

The examples section of the documentation includes examples for a UnicodeReader and UnicodeWriter wrapper classes (thanks @AlexeyKachayev for the pointer).