Export csv with web2py

In controller, forxample default.py:

def export_csv():
  
    animals = db().select(db.purchase_type.ALL)
    fname='hello.csv'
  
    return dict(animals1=animals, fname=fname)

In view: view/default folder:
make flie export_csv.csv:

{{
import cStringIO
stream=cStringIO.StringIO()
animals1.export_to_csv_file(stream)
response.headers['Content-Type']='application/vnd.ms-excel'
response.headers['Content-disposition']='attachment;filename='+fname
response.write(stream.getvalue(), escape=False)
}} 

Save to system file?, simple:
f = open('hello.csv', 'w')
f.write(stream.getvalue())
f.close()

Enjoy!