Yes. Thanks to both replies. I had a look at StringIO src in the
meantime and noticed that there isn't much to implement at all (as the
Jammer example also demonstrates).
Regards,
HC
On May 26, 7:47 pm, SergeyPo <ser...@zarealye.com> wrote:
> There is an example of string streaming on the site, and I have
> implemented my streaming controller function using this example (yes,
> it involves diving into file interface but not too much):
>
> #class streams long CSV to file-like object
> #I pasted it here unchanged, so code may be excessive
> class CSVstreamer():
> def __init__(self, conditions, output_fields):
> self.rs = db(eval(conditions)).select()
> self.outfile = cStringIO.StringIO()
> self.writer = csv.writer(self.outfile, dialect='excel-tab')
> self.columns = [f for f in output_fields if not
> f.adv_omit_download]
> row = [T(f.name) for f in self.columns]
> self.writer.writerow(row)
> self.iterator = self.make_iterator()
> def make_iterator(self):
> for rec in self.rs:
> row = [none_exception(eval('rec.' + str(f))) for f in
> self.columns]
> self.writer.writerow(row)
> yield self.outfile.getvalue()
> #the following is tricky part but without this file
> redefining the thing does not work
> #it appears that if gluon streamer tries to stream
> something that is not yet ready
> #it stops streaming until EOF is generated... better ask
> Massimo why :-)
> self.outfile.close()
> self.outfile = cStringIO.StringIO()
> self.writer = csv.writer(self.outfile, dialect='excel-
> tab')
> def read(self, n):
> n = self.iterator.next()
> return n
>
> #controller function that streams LONG csv-string to browser
> def download_csv():
> cond = 'db.table.id > 0'
> outfields = ['a', 'b', 'c']
> response.headers['Content-Type'] = 'application/octet-stream'
> response.headers['Content-Disposition'] = 'attachment;
> filename=download.csv'
> return response.stream(CSVstreamer(cond, outfields), 64)
>
> On May 26, 8:34 pm, hcvst <hcv...@googlemail.com> wrote:
>
> > Hi,
>
> > I would like to 'stream' results to the browser as they become
> > available.
>
> > Something like:
> > ---
> > response.write(lengthy_op(1))
> > response.flush()
> > response.write(lengthy_op(2))
> > response.flush()
> > ...
>
> > I am now thinking of extending StringIO to write sth like
>
> > response.stream(MyStringIO( [ (lengthy_op, 1), (lengthy_op, 2) ] ))
>
> > but I don't feel like diving into the file interface and ending up
> > with probably messy code
> > if there is a solution available already.
>
> > As always, thanks for web2py and the great support,
> > HC
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