Python - generate csv file in memory and then encode its data into base64?

Question

I need to generate csv file like data in memory and then encode it to base64, so I could save it. So basically I don't want to create file in hard disk for that. Now I solve this by creating csv file then encoding its data, saving it and then just simply removing csv file (because it is no longer needed). But is there a way to skip file creation, but save data the same way? I mean that data would be used to open csv file again using base64.

import base64
import csv
from StringIO import StringIO
import os

def test_binary(self):
    mylist = [['a', 'b'], ['c', 'd']]
    with open("test.csv", "wb") as f:
        writer = csv.writer(f)
        writer.writerows(mylist)   

    myfile = open('test.csv', 'r')
    stream = StringIO(myfile.read())

    encoded = base64.b64encode(stream.getvalue())

    self.test = encoded
    myfile.close()
    os.remove('test.csv')        

Answer 1

You could pass StringIO() to the csv writer directly:

>>> import base64
>>> import csv
>>> from io import StringIO
>>> mylist = [['a', 'b'], ['c', 'd']]
>>> f = StringIO()
>>> csv.writer(f).writerows(mylist)
>>> base64.b64encode(f.getvalue().encode())
b'YSxiDQpjLGQNCg=='

Python 2

>>> import base64
>>> import csv
>>> from StringIO import StringIO
>>> mylist = [['a', 'b'], ['c', 'd']]
>>> f = StringIO()
>>> csv.writer(f).writerows(mylist)
>>> base64.b64encode(f.getvalue())
'YSxiDQpjLGQNCg=='