Django FileField encoding

I have a django model as follows:

class ExportFile(BaseExportFile): 
    created_timestamp = models.DateTimeField(auto_now=True, editable=False)
    data = models.FileField(upload_to='exports')

and a view function that renders a template to create a csv file:

def create_csv(request):

        context = Co开发者_Python百科ntext({'data': MyModel.objects.all()})
        rendered = render_to_string('mytemplate.html', context)

        # create tradefile and save
        cf = ContentFile(rendered)

        tf = ExportFile()
        tf.data.save('myfile.csv', cf)

        tf.save()

        response =  HttpResponse(mimetype='text/csv')
        response['Content-Disposition'] = 'attachment; filename=%s' % 'myfile.csv'
        response.write(rendered)

        return response

The view not only saves the csv data to a FileField but it also returns it to the browser. The problem I have is the browser file works perfectly, but the file saved on the model is twice the size and when I use a diff program I can see extra hidden characters. I think it must be to do with the mime type vs django auto saving utf8 but I just can't figure it out!

Solved the problem!

The ContentFile is a subclass of cStringIO.StringIO - which deals with ASCII encoded files. The string therefore needs to be encoded as ASCII as everything in django is UTF8 by default

cf = ContentFile(rendered.encode('ascii'))