title: Convert CSV to excel using xlsxwriter and save it to django Model
body: <p>Now I don't have any problems about converting this csv or downloading it I have a problem saving it to django model at filefield
  The minmized sample code:</p>
  
  <pre><code>def download_convert_reports_s3_temp():
      def get_report_url():
          bucket_name = 'temp_bucket'
          conn = boto.connect_s3(AWS_ACCESS_KEY_ID,
                                 AWS_SECRET_ACCESS_KEY)
          bucket = conn.get_bucket(bucket_name)
          key = bucket.get_key('TEMP_2017-01-10.csv')
          return key.generate_url(expires_in=600)
  
      def get_doc():
          return Doc.objects.get(owner=User.objects.first())
  
      def get_file(file):
          file_temp = NamedTemporaryFile(delete=True)
          file_temp.write(file.content)
          file_temp.flush()
          return File(file_temp)
  
      def convert_csv_to_xlsx():
          request = requests.get(get_report_url())
          csvfile = get_file(request)
  
          from django.conf import settings
          excelFile = xlsxwriter.Workbook('report.xlsx', {
                                              'strings_to_numbers': True,
                                              'default_date_format': 'yy/mm/dd',
                                              'tmpdir': settings.MEDIA_ROOT +
                                                        '/documents/%s'.format(file.name.rsplit('.')[0] + '.xlsx')
                                          }
  
          excelFile = get_doc().file
          worksheet = excelFile.add_worksheet()
          worksheet.write('A1', 'data')
          worksheet.write('B1', 'data')
          worksheet.write('C1', 'data')
          worksheet.write('D1', 'data')
          worksheet.write('E1', 'data')
          # Start from the first cell. Rows and columns are zero indexed.
          row = 1
          col = 0
          with open(csvfile, 'rb') as f:
              content = csv.reader(f)
              # Iterate over the data and write it out row by row.
              for row_data in content:
                  for data in row_data:
                      worksheet.write(row, col, data)
                      col += 1
                  row += 1
                  col = 0
  
          f.close()
          excelFile.close()
  
      return convert_csv_to_xlsx()
  </code></pre>
  
  <p>Now the problem that I really don't know to to save this excel file to the <code>doc.file</code>, 
  and I tried django <a href="https://docs.djangoproject.com/en/1.10/ref/models/fields/#django.db.models.fields.files.FieldFile.save" rel="nofollow noreferrer">fieldfile save</a></p>
  
  <p><code>---&gt; 19     read = property(lambda self: self.file.
  AttributeError: 'Workbook' object has no attribute 'read'</code>
  Any suggestion Thanks</p>