[Catalyst] Setting file handle as the response body generates warnings.

[Craig Chant]

I've been using this for while....

    # check for ok status
    if($result->ok)
    {

        # output header
        $c->response->content_type('application/vnd.ms-excel');
        $c->response->content_length(length($xls));
        $c->response->header(Content_Disposition => 'attachment;filename=NBCS_Export.csv');

        # create an IO::File for Catalyst
        use IO::File;
        my $iof = IO::File->new;

        # open XLS
        $iof->open(\$xls, "r");

        # output XLS data
        $c->response->body($iof);

        # close file
        undef $iof;
    }

It resolves the out of memory issue if you try to print direct to $c->response->body without putting the content in an IO::File object.


From: John Napiorkowski [mailto:jjn1056 at yahoo.com]
Sent: 26 November 2013 01:54
To: The elegant MVC web framework
Subject: Re: [Catalyst] Setting file handle as the response body generates warnings.

We should probably document what it means by $c->response->body can accept a file handle.  Like plack specifies the interface it must deal with.  Anyone up to that?

This FH in body thing is something I've been thinking about a lot lately, in regards to when Catalyst is running under an event loop for example, should Catalyst stream the Filehandle a non blocking manner.  But it would be great to document this.  Also, I am thinking setting the default size when its missing could really belong to middleware.  Plack has some default middleware that does this:

https://metacpan.org/source/MIYAGAWA/Plack-1.0030/lib/Plack/Middleware/ContentLength.pm

the means it works looks like this

https://metacpan.org/source/MIYAGAWA/Plack-1.0030/lib/Plack/Util.pm#L68

There's a few things in Catalyst.pm that could profitable just use Plack::Middleware counterparts.

just a thought.

johnnap

On Thursday, November 21, 2013 9:20 AM, neil.lunn <neil at mylunn.id.au<mailto:neil at mylunn.id.au>> wrote:
On 22/11/2013 12:33 AM, Bill Moseley wrote:


On Wed, Nov 20, 2013 at 11:32 PM, neil.lunn <neil at mylunn.id.au<mailto:neil at mylunn.id.au>> wrote:

This approach may work for you is the compressed data is actually in a scalar and not too large. And not too small. YMMV.

my $z = read_file "product.json.gz";

my $io = IO::Scalar->new( \$z );
$io->seek( -4, 2 );
$io->read( my $buf, 4);

my $uncompressed_size = unpack( 'V', $buf );


This indeed does work in my tests.   Thanks for all the help, Neil.   I really appreciate the time you spent on this.

No prob. Part of my thing on list reponses is that there is a seed for others to learn from what was discussed.
I do wonder if there is a sane way to test for an in memory file handle and give a more appropriate warning, but that is for further discussion.



--
Bill Moseley
moseley at hank.org<mailto:moseley at hank.org>



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