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lib/Amon2/Plugin/Web/JSON.pm  view on Meta::CPAN

=head1 METHODS

=over 4

=item C<< $c->render_json(\%dat); >>

Generate JSON data from C<< \%dat >> and returns instance of L<Plack::Response>.

=back

=head1 PARAMETERS

=over 4

=item status_code_field

It specify the field name of JSON to be embedded in the 'X-API-Status' header.
Default is C<< undef >>. If you set the C<< undef >> to disable this 'X-API-Status' header.

    __PACKAGE__->load_plugins(
        'Web::JSON' => { status_code_field => 'status' }
    );
    ...
    $c->render_json({ status => 200, message => 'ok' })
    # send response header 'X-API-Status: 200'

In general JSON API error code embed in a JSON by JSON API Response body.
But can not be logging the error code of JSON for the access log of a general Web Servers.
You can possible by using the 'X-API-Status' header.

=item canonical

If canonical parameter is true, then this plugin will output JSON objects by sorting their keys.
This is adding a comparatively high overhead.

    __PACKAGE__->load_plugins(
        'Web::JSON' => { canonical => 1 }
    );
    ...
    $c->render_json({ b => 1, c => 1, a => 1 });
    # json response is '{ "a" : 1, "b" : 1, "c" : 1 }'

=back

=head1 FAQ

=over 4

=item How can I use JSONP?

You can use JSONP by using L<Plack::Middleware::JSONP>.

=back

=head1 JSON and security

=over 4

=item Browse the JSON files directly.

This module escapes '<', '>', and '+' characters by "\uXXXX" form. Browser don't detects the JSON as HTML.

And also this module outputs C<< X-Content-Type-Options: nosniff >> header for IEs.

It's good enough, I hope.

=item JSON Hijacking

Latest browsers doesn't have a JSON hijacking issue(I hope). __defineSetter__ or UTF-7 attack was resolved by browsers.

But Firefox<=3.0.x and Android phones have issue on Array constructor, see L<http://d.hatena.ne.jp/ockeghem/20110907/p1>.

Firefox<=3.0.x was outdated. Web application developers doesn't need to add work-around for it, see L<http://en.wikipedia.org/wiki/Firefox#Version_release_table>.

L<Amon2::Plugin::Web::JSON> have a JSON hijacking detection feature. Amon2::Plugin::Web::JSON returns "403 Forbidden" response if following pattern request.

=over 4

=item The request have 'Cookie' header.

=item The request doesn't have 'X-Requested-With' header.

=item The request contains /android/i string in 'User-Agent' header.

=item Request method is 'GET'

=back

=back

See also the L<hasegawayosuke's article(Japanese)|http://www.atmarkit.co.jp/fcoding/articles/webapp/05/webapp05a.html>.

=head1 FAQ

=over 4

=item HOW DO YOU CHANGE THE HTTP STATUS CODE FOR JSON?

render_json method returns instance of Plack::Response. You can modify the response object.

Here is a example code:

    get '/' => sub {
        my $c = shift;
        if (-f '/tmp/maintenance') {
            my $res = $c->render_json({err => 'Under maintenance'});
            $res->status(503);
            return $res;
        }
        return $c->render_json({err => undef});
    };

=back

=head1 THANKS TO

hasegawayosuke