/ 
Catalyst-View-JSON-0.10
River stage two • 17 direct dependents • 18 total dependents
/ Catalyst::View::JSON

NAME

Catalyst::View::JSON - JSON view for your data

SYNOPSIS

# lib/MyApp/View/JSON.pm
package MyApp::View::JSON;
use base qw( Catalyst::View::JSON );
1;

# configure in lib/MyApp.pm
MyApp->config({
    ...
    'V::JSON' => {
        allow_callback  => 1,    # defaults to 0
        callback_param  => 'cb', # defaults to 'callback'
        expose_stash    => [ qw(foo bar) ], # defaults to everything
    },
});

sub hello : Local {
    my($self, $c) = @_;
    $c->stash->{message} = 'Hello World!';
    $c->forward('MyApp::View::JSON');
}

DESCRIPTION

Catalyst::View::JSON is a Catalyst View handler that returns stash data in JSON format.

CONFIG VARIABLES

allow_callback

Flag to allow callbacks by adding callback=function. Defaults to 0 (doesn't allow callbacks). See "CALLBACKS" for details.

callback_param

Name of URI parameter to specify JSON callback function name. Defaults to callback. Only effective when allow_callback is turned on.

expose_stash

Scalar, List or regular expression object, to specify which stash keys are exposed as a JSON response. Defaults to everything. Examples configuration:

# use 'json_data' value as a data to return
expose_stash => 'json_data',

# only exposes keys 'foo' and 'bar'
expose_stash => [ qw( foo bar ) ],

# only exposes keys that matches with /^json_/
expose_stash => qr/^json_/,

Suppose you have data structure of the following.

$c->stash->{foo} = [ 1, 2 ];
$c->stash->{bar} = [ 3, 4 ];

By default, this view will return:

{"foo":[1,2],"bar":2}

When you set expose_stash => [ 'foo' ], it'll return

{"foo":[1,2]}

and in the case of expose_stash => 'foo', it'll just return

[1,2]

instead of the whole object (hashref in perl). This option will be useful when you share the method with different views (e.g. TT) and don't want to expose non-irrelevant stash variables as in JSON.

ENCODINGS

Due to the browser gotchas like those of Safari and Opera, sometimes you have to specify a valid charset value in the response's Content-Type header, e.g. text/javascript; charset=utf-8.

Catalyst::View::JSON comes with the configuration variable encoding which defaults to utf-8. You can change it via YourApp->config or even runtime, using component.

$c->component('View::JSON')->encoding('euc-jp');

This assumes you set your stash data in raw euc-jp bytes, or Unicode flagged variable. In case of Unicode flagged variable, Catalyst::View::JSON automatically encodes the data into your encoding value (euc-jp in this case) before emitting the data to the browser.

Another option would be to use JavaScript-UCS as an encoding (and pass Unicode flagged string to the stash). That way all non-ASCII characters in the output JSON will be automatically encoded to JavaScript Unicode encoding like \uXXXX. You have to install Encode::JavaScript::UCS to use the encoding.

CALLBACKS

By default it returns raw JSON data so your JavaScript app can deal with using XMLHttpRequest calls. Adding callbacks to the API gives more flexibility to the end users of the API: overcome the cross-domain restrictions of XMLHttpRequest. It can be done by appending script node with dynamic DOM manipulation, and associate callback handler to the returned data.

For example, suppose you have the following code.

sub end : Private {
    my($self, $c) = @_;
    if ($c->req->param('output') eq 'json') {
        $c->forward('MyApp::View::JSON');
    } else {
        ...
    }
}

/foo/bar?output=json will just return the data set in $c->stash as JSON format, like:

{ result: "foo", message: "Hello" }

but /foo/bar?output=json&callback=handle_result will give you:

handle_result({ result: "foo", message: "Hello" });

and you can write a custom handle_result function to handle the returned data asynchronously.

The valid characters you can use in the callback function are

[a-zA-Z0-9\.\_\[\]]

but you can customize the behaviour by overriding the validate_callback_param method in your View::JSON class.

See Yahoo's nice explanation on http://developer.yahoo.net/common/json.html

AUTHOR

Tatsuhiko Miyagawa <miyagawa@bulknews.net>

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO

Catalyst, JSON, Encode::JavaScript::UCS