Streams a list as a CSV. Useful if you need to return a database query in a way which the user can immediately import to a spreadsheet.

Here is an example use in a controller:

def view_payment_details():
    form=FORM('Date 1:', INPUT(_name='date1',_class='date',_size=10,requires=IS_DATE(format='%Y-%m-%d',error_message='must be YYYY-MM-DD')),'Date 2:',
              INPUT(_name='date2',_class='date',requires=IS_DATE(format='%Y-%m-%d',error_message='must be YYYY-MM-DD')),
              INPUT(_type='submit'),keepvalues=True)
    accpac_orders = {}
    
    if form.accepts(request,session):
        date1_ymd = request.vars.date1
        date2_ymd = request.vars.date2

        #next line gets a list of records as a result of a database query
        accpac_orders = reconcile.get_accpac_orders(date1_ymd, date2_ymd)
        

        field_names = ('Order Nbr','Invoice Nbr' ,'Location','Reference','Order Date','Invoice Date','Amount Paid','Amount Invoiced')
        
        response.view='generic_list.csv'
        return dict(filename='accpac_payment_details.csv', csvdata=accpac_orders,field_names=field_names)

     return dict(form=form,date1=date1_ymd)

Below is the contents of views/generic_list.csv

{{
###
# Stream a CSV
# for this to work the controller must return
#
#   dict(filename=...,csvdata=...,field_names=...)
#
# filename is the suggested name to save the file as
# csvdata is the list to output
# field_names is a list of column headers
###
try:
   thefile = filename
except:
   thefile = 'export.csv'
pass
# the try block is commented out because it obscures errors that 
# may be interesting while debugging
#try:
   import cStringIO
   import csv
   stream=cStringIO.StringIO()
   #field_names = ('Order Nbr','Invoice','Location','Payment ID','Date1','Date2','Amount1','Amount2')
  
   csv_writer = csv.writer(stream)
   csv_writer.writerow(field_names)
   for row in csvdata:
      csv_writer.writerow(row)
      pass
   
   response.headers['Content-Type']='application/vnd.ms-excel'
   response.headers['Content-disposition']='attachment; filename=' +thefile
   response.write(stream.getvalue(), escape=False)
#except:
#   raise HTTP(405,'no css')
}}