NAME

WebService::GData::Feed - Base class wrapping json atom feed for google data API v2.

SYNOPSIS

use WebService::GData::Feed;

my $feed = new WebService::GData::Feed($jsonfeed);

$feed->title;
$feed->author;
my @entries = $feed->entry();#send back WebService::GData::Feed::Entry or a service related Entry object 

DESCRIPTION

inherits from WebService::GData

This package wraps the result from a query using the json format of the Google Data API v2 (no other format is supported!). It gives you access to some of the data via wrapper methods and works as a factory to get access to the entries for each service. If you use a YouTube service, calling the entry() method will send you back YouTube::Feed::Entry's. If you use a Calendar service, calling the entry() method will send you back a Calendar::Feed::Entry. By default, it returns a WebService::GData::Feed::Entry which gives you only a read access to the data. Unless you implement a service, you should not instantiate this class directly.

CONSTRUCTOR

new

Create a WebService::GData::Feed instance.

Accept a json feed entry that has been perlified (from_json($json_string)) and an optional request object (WebService::GData::Base). The request object is passed along each entry classes but the Feed class itself does not use it.

Parameters

json_feed:Object - a json feed perlified

request:Object - a request object WebService::GData::Base

Returns

WebService::GData::Feed

SET/GET METHODS

All the following methods work as both setter and getters.

title

set/get the title of the feed.

Parameters

none - as a getter

title:Scalar as a setter

Returns

none - as a setter

title:Scalar as a getter

Example:

use WebService::GData::Feed;

my $feed = new WebService::GData::Feed();

$feed->title("my Title");

$feed->title();#my Title

GET METHODS

All the following methods work as getters and do not accept parameters.

id

Get the id of the feed.

Parameters

none - getter

Returns

id:Scalar

Example:

 use WebService::GData::Feed;
 
 my $feed = new WebService::GData::Feed($jsonfeed);
 
 $feed->id();#"tag:youtube.com,2008:video"

updated

Get the updated date of the feed.

Parameters

none - getter

Returns

updated:Scalar

Example:

 use WebService::GData::Feed;
 
 my $feed = new WebService::GData::Feed($jsonfeed);
 
 $feed->updated();#"2010-09-20T13:49:20.028Z"

category

Get the categories of the feed. At the feed level, it is almost always one category that defines the kind of the feed (video feed, related feed,etc). The entry() uses this information to load the proper class, ie Video or Comment entries.

Parameters

none - getter

Returns

categories:Collection - WebService::GData::Collection containing WebService::GData::Node::Category.

Example:

use WebService::GData::Feed;

my $feed = new WebService::GData::Feed($jsonfeed);

my $categories = $feed->category();
foreach my $category (@$categories) {
    #$category->scheme,$category->term,$category->label
}

#search for a particular kind of category
my $kind = $categories->scheme('kind')->[0];

#json feed category is as below:
"category": [
  {
   "scheme": "http://schemas.google.com/g/2005#kind",
   "term": "http://gdata.youtube.com/schemas/2007#video"
  }
]
  

etag

Get the etag of the feed. The etag is a unique identifier key to track updates to the document.

Parameters

none - getter

Returns

etag:Scalar - the etag value

Example:

 use WebService::GData::Feed;
 
 my $feed = new WebService::GData::Feed($jsonfeed);
 
$feed->etag();#W/\"CkICQX45cCp7ImA9Wx5XGUQ.\"

See also http://code.google.com/intl/en/apis/gdata/docs/2.0/reference.html#ResourceVersioning for further information about resource versioning.

author

Get the author of the feed.

Parameters

none - getter

Returns

author:Collection - WebService::GData::Collection containing WebService::GData::Node::AuthorEntity.

Example:

 use WebService::GData::Feed;
 
 my $feed = new WebService::GData::Feed($jsonfeed);
 
my $authors=  $feed->author();

foreach my $author (@$authors){
    #$author->name,$author->uri
}

#raw json feed:

"author": [
  {
    "name": {
     "$t": "YouTube"
    },
    "uri": {
     "$t": "http://www.youtube.com/"
    }
   }
 ],

PAGINATION RELATED METHODS

The following methods sent back information that can be useful to paginate the result. You get access to the number of result, the number of item sent and the offset from which the result start.

total_items

Get the total result of the feed.

Parameters

none - getter

Returns

total_items:Int - the total number of items

Example:

use WebService::GData::Feed;

my $feed = new WebService::GData::Feed($jsonfeed);

$feed->total_items();#1000000

total_results

Get the total result of the feed. Alias for total_items

Parameters

none - getter

Returns

total_results:Int - the total number of items

Example:

use WebService::GData::Feed;

my $feed = new WebService::GData::Feed($jsonfeed);

$feed->total_results();#1000000

start_index

Get the start number of the feed.

Parameters

none - getter

Returns

start_index:Int - the start index of the feed counting from 1.

Example:

use WebService::GData::Feed;

my $feed = new WebService::GData::Feed($jsonfeed);

$feed->start_index();#1

items_per_page

Get the the number of items sent per result.

Parameters

none - getter

Returns

items_per_page:Int - the number of item in the result.

Example:

use WebService::GData::Feed;

my $feed = new WebService::GData::Feed($jsonfeed);

$feed->items_per_page();#25

links

Get the links of the feed in a array reference.

Parameters

none - getter

Returns

links:Collection - WebService::GData::Collection containing WebService::GData::Node::Link instances. =back

Example:

use WebService::GData::Feed;

my $feed = new WebService::GData::Feed($jsonfeed);

my $links = $feed->links();
foreach my $link (@$links){
    #link->rel,$link->type,$link->href
}

#raw json data:

  "link": [
   {
    "rel": "alternate",
    "type": "text/html",
    "href": "http://www.youtube.com"
   },
   {
    "rel": "http://schemas.google.com/g/2005#feed",
    "type": "application/atom+xml",
    "href": "http://gdata.youtube.com/feeds/api/videos"
   },
   {
    "rel": "http://schemas.google.com/g/2005#batch",
    "type": "application/atom+xml",
    "href": "http://gdata.youtube.com/feeds/api/videos/batch"
   }
  ]

get_link

Get a specific link entry by looking in the rel attribute of the link tag.

Parameters

link_type:Scalar - set the type of link you are looking for.

Returns

undef - if the link is not found.

url:Scalar - the contents in href if the link is found.

Example:

use WebService::GData::Feed;

my $feed = new WebService::GData::Feed($jsonfeed);

my $previous_url= $feed->get_link('previous');

my $batch_url   = $feed->get_link('batch');

previous_link

Get a the previous link if set or undef. Shortcut for $feed->get_link('previous');

next_link

Get a the next link if set or undef. Shortcut for $feed->get_link('next');

entry

This method return an array reference of Feed::* objects.

It works as a factory by instantiating the proper Feed::* class.

For example,if you read a video feed from a youtube service, it will instantiate the WebService::GData::Youtube::Feed::Video class and feed it the result.

It will look first at the category scheme set in the feed or at the entry category scheme that contains the base schema name of the feed.

If it does not guess properly,you can always specify the name of the package to load as its first argument.

Parameters

class_name::Scalar* - (optional) Force a specific class to be loaded and do not let entry guess the feed type on its own.

Returns

entries:ArrayRef - By default it uses WebService::GData::Entry::Feed but will return instances of the found package or of the specified one

Example:

use WebService::GData::Feed;

my $feed = new WebService::GData::Feed($jsonfeed);

my $entries = $feed->entry('WebService::GData::Feed::Entry');#force a particular class to be used
my $entries = $feed->entry();#let entry figure it out by looking at the feed meta information.

foreach my $entry (@$entries) {
    
    #$entry->title,$entry->id... all entry sub classes should inherit from WebService::GData::Feed::Entry
}   

JSON FEED EXAMPLE

Below is a raw json feed example from querying youtube videos. Only the relevant parts are listed.

The actual feed does contain more information but a possible switch to JSONC, freed of meta information, being possible, this package only offers wrapper methods to what is relevant in the JSONC context.

{
 "feed": {
  "gd$etag": "W/\"CkICQX45cCp7ImA9Wx5XGUQ.\"",
  "id": {
   "$t": "tag:youtube.com,2008:videos"
  },
  "updated": {
   "$t": "2010-09-20T13:49:20.028Z"
  },
  "category": [
   {
    "scheme": "http://schemas.google.com/g/2005#kind",
    "term": "http://gdata.youtube.com/schemas/2007#video"
   }
  ],
  "title": {
   "$t": "YouTube Videos"
  },
  "link": [
   {
    "rel": "alternate",
    "type": "text/html",
    "href": "http://www.youtube.com"
   },
   {
    "rel": "http://schemas.google.com/g/2005#feed",
    "type": "application/atom+xml",
    "href": "http://gdata.youtube.com/feeds/api/videos"
   },
   {
    "rel": "http://schemas.google.com/g/2005#batch",
    "type": "application/atom+xml",
    "href": "http://gdata.youtube.com/feeds/api/videos/batch"
   },
   {
    "rel": "self",
    "type": "application/atom+xml",
    "href": "http://gdata.youtube.com/feeds/api/videos?alt=json&start-index=1&max-results=25"
   },
   {
    "rel": "service",
    "type": "application/atomsvc+xml",
    "href": "http://gdata.youtube.com/feeds/api/videos?alt\u003datom-service"
   },
   {
    "rel": "next",
    "type": "application/atom+xml",
    "href": "http://gdata.youtube.com/feeds/api/videos?alt=json&start-index=3&max-results=25"
   }
  ],
  "author": [
   {
    "name": {
     "$t": "YouTube"
    },
    "uri": {
     "$t": "http://www.youtube.com/"
    }
   }
  ],
  "openSearch$totalResults": {
   "$t": 1000000
  },
  "openSearch$startIndex": {
   "$t": 1
  },
  "openSearch$itemsPerPage": {
   "$t": 25
  },
  "entry": [....]#erased as there are implemented in each sub classes
 }
}

BUGS AND LIMITATIONS

If you do me the favor to _use_ this module and find a bug, please email me i will try to do my best to fix it (patches welcome)!

AUTHOR

shiriru <shirirulestheworld[arobas]gmail.com>

LICENSE AND COPYRIGHT

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

cpanm WebService::GData

perl -MCPAN -e shell
install WebService::GData