How to generate a file without saving it to disk in python?

Question

I'm using Python 2.7 and Django 1.7.

I have a method in my admin interface that generates some kind of a csv file.

def generate_csv(args):
    ...
    #some code that generates a dictionary to be written as csv
    ....

    # this creates a directory and returns its filepath
    dirname = create_csv_dir('stock')

    csvpath = os.path.join(dirname, 'mycsv_file.csv')
    fieldnames = [#some field names]

    # this function creates the csv file in the directory shown by the csvpath
    newcsv(data, csvheader, csvpath, fieldnames)

    # this automatically starts a download from that directory
    return HttpResponseRedirect('/media/csv/stock/%s' % csvfile)

All in all I create a csv file, save it somewhere on the disk, and then pass its URL to the user for download.

I was thinking if all this can be done without writing to disc. I googled around a bit and maybe content disposition attachment might help me, but I got lost in documentation a bit.

Anyway if there's an easier way of doing this I'd love to know.

Answer 1

Thanks to @Ragora, you pointed me towards the right direction.

I rewrote the newcsv method:

from io import StringIO
import csv


def newcsv(data, csvheader, fieldnames):
    """
    Create a new csv file that represents generated data.
    """
    new_csvfile = StringIO.StringIO()
    wr = csv.writer(new_csvfile, quoting=csv.QUOTE_ALL)
    wr.writerow(csvheader)
    wr = csv.DictWriter(new_csvfile, fieldnames = fieldnames)

    for key in data.keys():
        wr.writerow(data[key])

    return new_csvfile

and in the admin:

csvfile = newcsv(data, csvheader, fieldnames)

response = HttpResponse(csvfile.getvalue(), content_type='text/csv')
response['Content-Disposition'] = 'attachment; filename=stock.csv'
return response