Hello,

Odoo already have method for download file from binary data.

    @http.route('/web/binary/saveas', type='http', auth="public")

    @serialize_exception

    def saveas(self, model, field, id=None, filename_field=None, **kw):

         -------

         -------

This method available on '/web/controllers/main.py'

You can use this method by pass parameter in url.

Example:

URL : localhost:8069/web/binary/saveas?model=ir.attachment&field=datas&filename_field=datas_fname&id=103

Using this url odoo will give you data of field datas from ir.attachment model of record id is 103.

------------------------- Code is For reading Excel file that store in Binary format--------------------------

import base64

from openerp import api, fields, models, _

from openpyxl import load_workbook

class ExcelRead(models.TransientModel):

     _name = "excel.read"

     data_file=fields.Binary('File')

     @api.one

     def import_file(self):

        data_file_p = open('/tmp/test.xlsx','w')

         data_file_p.write((base64.b64decode(self.data_file)))

         data_file_p.close()

         wb = load_workbook('test.xlsx')

         ws = wb['big_data']

         for row in ws.rows:

             for cell in row:

                 print(cell.value)

Hope this helps.