I wrote something similar to what you want. It outputs the file
directly instead of creating an intermediate file. In my case I'm
selecting a set of fields in a big "join" but you can get the idea.
The "hash" function is just to create a signature so I can tell if
some of the fields were changed when I read the CSV file back in a
later step.
Just create a file-like object from StringIO, write to it, reset it to
the beginning, and return it as a stream.
def export_signup_sheet():
if not request.args:
request.flash='No selection for team and meet.'
return
(meetId,teamId)=request.args[0:2]
exp=StringIO()
dbsignups=db((db.signup.id_team_member==db.team_member.id)&
(db.signup.id_meet_event==db.meet_event.id)\
&(db.meet_event.id_meet==meetId)&
(db.team_member.id_team==teamId)\
&(db.event.id==db.meet_event.id_event)&
(db.swimmer.id==db.team_member.id_swimmer))
rows=dbsignups.select(orderby=db.swimmer.last|db.swimmer.first|
db.meet_event.indx)
filehash=hashlib.md5()
exp.write('ID,Last name,First name,Event,Race,Course,Time\n')
for row in rows:
race='%s%s %s'%
(row.event.distance,row.event.course,event_stroke[row.event.stroke])
exp.write('%s,%s,%s,%s,%s,%s,%s\n'%
(row.signup.id,row.swimmer.last,row.swimmer.first,row.meet_event.indx,
race,row.signup.course,s_to_t2(row.signup.best_time)))
filehash.update(str(row.signup.id)+row.swimmer.last
+row.swimmer.first+str(row.meet_event.indx)+race)
exp.write('hash,%s\n'%filehash.hexdigest())
exp.flush()
exp.seek(0)
response.headers['Content-Type']='text/application'
response.headers['Content-Disposition']='attachment;
filename="%s.csv"'%'Meet_Signup'
return response.stream(exp)
On Mar 13, 12:32 pm, SergeyPo <[email protected]> wrote:
> Hi all,
>
> can you recommend an elegant way to download CSV file from web2py?
> Using gluon code, I wrote a controller function that creates good CSV
> for me in cStringIO object, but my recordsets are large and I'd like
> to stream download file. I.e. approach when I write temp file and then
> download it is not good - I want to start file streaming to user
> immediately, definitely this involves some manipulations with response
> object...
>
> My controller:
>
> def download_csv():
> def none_exception(value): #taken from gluon.sql
> if isinstance(value, unicode):
> return value.encode('utf8')
> if hasattr(value, 'isoformat'):
> return value.isoformat()[:19].replace('T', ' ')
> if value == None:
> return ''
> return value
>
> sqlset = ........
> rs = db(sqlset).select()
> outfile = cStringIO.StringIO()
> writer = csv.writer(outfile, dialect='excel-tab')
> columns = [f for f in fields_array if not f.adv_omit_download]
> row = [T(f.name) for f in columns]
> writer.writerow(row)
> for rec in rs:
> row = [none_exception(eval('rec.' + str(f))) for f in columns]
> writer.writerow(row)
> outfile.getvalue() #contains valid CSV string but I want to stream
> it to user during cycle over rs
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