Hello Matt,
Thanks for your response. The page I serve has a graph plus a link to
a csv file of the graph data so I can't dynamically return the data as
you suggest. The page looks like this.
<html><title>demand</title></head><body>
<a href="/tmp/demand.png" title="/tmp/demand">
<img id="/tmp/demand" src="/tmp/demand.png" width="300"
height="200" />
</a></br>
<a href="/tmp/demand__2008-10-29_2008-10-30.csv">csv</a></br>
</body></html>
Using tempfile.NamedTemporaryFile specifying this tmp directory could
be an improvement if the deletion works ok. If I don't explictly close
the file the docs say they will be closed and therefore deleted with
gc is run.
On Dec 10, 7:05 pm, "Matthew Zwier" <mczw...@gmail.com> wrote:
> Hello,
>
> Do you need the graphics files to remain around for a while, or are
> they dynamically generated for one request? If the former, the
> approach being discussed here makes a lot of sense. The files you
> create will be around until you delete them yourself. If the latter
> (read data from constantly-updated source, make graph, put on page --
> that sort of thing), you may be better suited rendering the graphics
> into a temporary file (as created with tempfile.NamedTemporaryFile or
> whatever) and streaming it to the client yourself.
>
> # at the top of the controller file
> import tempfile
>
> class ChunkedFileIter(object):
> """An iterator interface which reads chunks of a given size from a file
> until the file ends.
> """
>
> def __init__(self, fileobj, blocksize = 8192):
> """Initialize this object.
>
> :Parameters:
> fileobj : object supporting ``read(blocksize)``
> File object from which to read
> blocksize : integer
> Number of bytes to read in each iteration
> """
> self.fileobj = fileobj
> self.blocksize = blocksize
>
> def __iter__(self):
> return self
>
> def next(self):
> """Read ``self.blocksize`` bytes from ``self.fileobj``. Raises
> ``StopIteration`` when the file ends."""
> dat = self.fileobj.read(self.blocksize)
> if not dat:
> raise StopIteration
> return dat
>
> # in your action:
> tf = tempfile.NamedTemporaryFile(suffix='.png')
> # Write graphic into the file named by tf.name
> makeGraphic(tf.name)
> # tf.flush() # <-- may be necessary if you write the file yourself,
> as opposed to an external program
> tf.seek(0)
> response.content_type='image/png'
> response.app_iter = ChunkedFileIter(tf)
>
> Using the NamedTemporaryFile ensures that the file is deleted after
> the request ends. You can then instruct the browser to cache its copy
> of the file (using etag_cache()) so you don't regenerate it unless the
> source data has changed or the client requests a new copy explicitly.
>
> That totally won't help if you need those PNGs laying around for
> future use...but as it took about five minutes of cut-and-paste...if
> it does help...great!
>
> Cheers,
> Matt Z.
>
> On Mon, Dec 8, 2008 at 5:30 AM, erowan <rowan.shul...@wanadoo.fr> wrote:
>
> > Hello,
>
> > I have a web app that dynamically generates images (png files). The
> > main html response page has links to these files
>
> > i.e.
> > <a href="/tmp/demand.png" title="/tmp/demand">
> > <img id="/tmp/demand" src="/tmp/demand.png" width="300"
> > height="200" />
>
> > I created the tmp dir under public and while running pylons in
> > development this worked ok. Basically these filepaths resolved to the
> > same location.
>
> > 1. os.path.join(config['app_conf']['public_dir'], 'tmp', filename)
> > 2. graph_file_name = h.url_for('/tmp/' + str(graph_file_name))
>
> > However, after packaging, install & deploying the app with the same
> > config file dev.ini
>
> > python setup.py bdist_egg
> > easy_install bmra_web-0.1.0dev-py2.5.egg
> > cd some_deployment_dir
> > paster serve dev.ini
>
> > The dirs are not the same. 1 is but 2 resolves under the ~site-
> > packages/bmra_web-0.1.0dev-py2.5.egg installation dir. I am not sure
> > how to handle this? Should I be using another StaticURLParser
> > instance for this tmp directory combined with Casade and maybe name it
> > _tmp (does this bypass the routes dispatching?).
>
> > I am a bit confused as to how to handle this. Thanks.
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