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

[John Napiorkowski]

Awesome, send me a pull request :)

https://github.com/perl-catalyst/catalyst-runtime




On Tuesday, November 26, 2013 1:24 AM, neil.lunn <neil at mylunn.id.au> wrote:
 =

On 26/11/2013 12:54 PM, John Napiorkowski wrote:

We should probably document what it means by $c->response->body can accept =
a file handle. =A0Like plack specifies the interface it must deal with. =A0=
Anyone up to that?
Something along these lines maybe?

Catalyst can accept a file handle type of object as the response
    body in the sense that the handle reasonably has a "read" method
    that will return content. In such a case and where no content length
    has been already set in the response headers catalyst will make a
    reasonable attempt to determine the size of the file. Depending on
    the implementation of your file handle object setting the content
    length may fail. If it is at all possible for you to determine the
    content length of your file handle, it is recomended that you set
    the content length in the response headers yourself, which will be
    respected and sent by catalyst in the response.


>
>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, sho=
uld Catalyst stream the Filehandle a non blocking manner. =A0But it would b=
e great to document this. =A0Also, I am thinking setting the default size w=
hen its missing could really belong to middleware. =A0Plack has some defaul=
t middleware that does this:
>
>
>https://metacpan.org/source/MIYAGAWA/Plack-1.0030/lib/Plack/Middleware/Con=
tentLength.pm
>
Which interestingly does not take a too different approach to what
    the Catalyst code is attempting. Also noting that in a case such as
    Bill presented it too would fail, which is only to be expected.

Noting such IO magic modules like IO::Uncompress::* and IO::Scalar
    etc and speaking of cat skinning, another approach could be
    subclassing these modues and overloading the file test operators to
    do something sane when used, and thus return a "correct" response
    when the -s test is used. Or try and convince said authors to have
    these classes do this natively.



>
>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> wrot=
e:
> =

>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> wrote:
>>
>>
>>>
This approach may work for you is the compressed data is actually in a scal=
ar and not too large. And not too small. YMMV.
>>>
>>>my $z =3D read_file "product.json.gz";
>>>
>>>my $io =3D IO::Scalar->new( \$z );
>>>$io->seek( -4, 2 );
>>>$io->read( my $buf, 4);
>>>
>>>my $uncompressed_size =3D unpack( 'V',
                                $buf );
>>
>>
>>
>>
>>This indeed does work in my tests. =A0 Thanks for all the help, Neil. =A0=
 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 othe=
rs 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 =

>>
>>
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