NAME

WebService::GData::Node - Abstract class representing an xml node/tag

SYNOPSIS

   #your package should use the abstract Node package.
   #it will automaticly inherit from it.
   
   #Author.pm files:
   use WebService::GData::Node::Author;
   use WebService::GData::Node;
   
   1;
   
   #Name.pm
   use WebService::GData::Node::Name;
   use WebService::GData::Node;  
   
   1; 
   
   #Category.pm
   package WebService::GData::Node::Category;
   use WebService::GData::Node;

   set_xml_meta(
        attributes=>['scheme','yt:term','label'],#default to []
        is_parent => 0, #default 1
        namespace_prefix => 'k', #default to ''
        tag_name  => 'category' # default to the package file name with the first letter in lower case
   );

   1;

    #user code:
        use WebService::GData::Node::Name();  #avoid to inherit from it by not importing
        use WebService::GData::Node::Author();
        use WebService::GData::Node::Category();
                
    my $author   = new WebService::GData::Node::Author();
    my $name     = new WebService::GData::Node::Name(text=>'john doe');
    my $category = new WebService::GData::Node::Category(scheme=>'author','yt:term'=>'Author');
    
    #or coming from a json feed:
    my $category = new WebService::GData::Node::Category({scheme=>'author','yt$term'=>'Author'});
    
    
    
    $author->child($name)->child($category);
    
    $name->text;#john doe
    $category->scheme;#author;
    $category->scheme('compositor');
    
    print $author;#<author><name>john doe</name><k:category scheme="compositor" yt:term="Author"/></author>

DESCRIPTION

inherits from WebService::GData

This package is an abstract class representing the information required to serialize a node object into xml. It regroups the mechanism to store the meta data about a node and from there built the proper xml output. It is not an all purpose class for building complex xml data. It does not parse xml either.

You should subclass and set the meta information via the set_xml_data function that will be installed in your package (see below for further explanation). You can instantiate this class if you want... it will not throw any error but you won't be able to do much.

A node is only the representation of one xml tag. Feed and Feed subclasses are the representation of an entire JSON response or offers a subset.

See also WebService::GData::Node::AbstractEntity.

CONSTRUCTOR

new

Create an instance but you won't be able to do much as no meaningful meta data has been set. You should inherit from this class.

Parameters

args:Hash (optional) - all the xml attributes can be set here. text nodes requires the "text" key. or

args:HashRef (optional) - all the xml attributes can be set here. text nodes requires the "text" key and the '$t' key is also supported as an alias for 'text' for compatibily with the GData JSON responses.

Returns

WebService::GData::Node

Example:

    use WebService::GData::Node;
        
    my $node   = new WebService::GData::Node(text=>'hi');
    
       $node->text();#hi;
       
   print $node;"<>hi<>"; #this is an abstract node!
        

OVERLOAD METHOD

__to_string

This class overwrite the default __to_string method to call serialize and output the xml data. Therefore if you use a Node object in a string context, you will get back its xml representation.

AUTOLOAD

__set/__get

The attributes setter/getters and the text method are generated on the fly.

* you can use either hyphen base notation or camelCase notation.

* Attributes containing namespaces can be accessed by replacing ':' with '_'. yt:format attribute can be set/get via the yt_format method. You should use the qualified attribute when setting it via the constructor. Therefore, new Node(yt_format=>1) will not work but new Node('yt:format'=>1) and new Node({'yt$format'=>1}) will work.

Example:

    use WebService::GData::Node::FeedLink;
    
    my $feedlink = new WebService::GData::Node::FeedLink($link);
    
    $feedlink->countHint;
    
    #or
    $feedlink->count_hint;

METHODS

child

Set an other node child of the instance. It returns the instance so you can chain the calls. You can not set the instance as a child of itself. The child method checks against the memory slot of the object and will return the instance without setting the object if it appears to be the same.

Parameters

node:WebService::GData::Node - a node instance inheriting from this class.

Returns

instance:WebService::GData::Node - you can chain the call

Example:

    my $author   = new WebService::GData::Node::Author();
    my $name     = new WebService::GData::Node::Name(text=>'john doe');
    my $category = new WebService::GData::Node::Category(scheme=>'author',term=>'Author');
    
    $author->child($name)->child($category);
    
    #the same object can not be a child of itself. which makes sense.
    #it just silently returns the instance.
    $author->child($author);

swap

This method will put a new instance instead of an existing child.

Parameters

oldchild::WebService::GData::Node|WebService::GData::Collection - the node to remove in the children collection

newchild::WebService::GData::Node|WebService::GData::Collection - the node to put instead

Returns

Cnone>

Example:

    my $author   = new WebService::GData::Node::Author();
    my $name     = new WebService::GData::Node::Name(text=>'john doe');
    my $category = new WebService::GData::Node::Category(scheme=>'author',term=>'Author');
    
    $author->child($name)->child($category);
    
    my $newname = new WebService::GData::Node::Name(text=>'billy doe');
    $author->swap($name,$newname);
    
           

serialize

This method will create the xml output of the instance and make recursive call to the serialize method of the children.

Parameters

none

Returns

xml_data:Scalar - the xml created

Example:

    my $author   = new WebService::GData::Node::Author();
    my $name     = new WebService::GData::Node::Name(text=>'john doe');
    my $category = new WebService::GData::Node::Category(scheme=>'author',term=>'Author');
    
    $author->child($name)->child($category);
    
    $author->serialize;#<author><name>john doe</name><k:category scheme="author" yt:term="Author"/></author>
           

The following methods are installed by default in the package subclassing this class. You should set their value via the set_xml_data method (see below).

namespace_prefix

tag_name

attributes

is_parent

INHERITANCE

The package will push itself in the inheritance chain automaticly when you use it so it is not necessary to explicitly declare the inheritance. As a consequence though, every sub classes that are used will also automaticly set themself in the inheritance chain of the user. In order to avoid this behavior you should write:

    use WebService::GData::Node(); 
 

The following function will be accessible in the sub class.

set_xml_data

Set the meta data of the node.

Parameters

args::Hash

namespace_prefix:Scalar - the namespace name of the tag, ie, yt:, media: ...

tag_name:Scalar - the name of the tag it sefl, ie, category, author...

attributes:ArrayRef - a list of the node attributes, ie, src, scheme... Default: []

is_parent:Int - specify if the node can accept children, including text node. Default: 1 (true),0 if not.

Returns install the methods in the package.

none

Example:

   #Category.pm
   package WebService::GData::Node::Category;
   use WebService::GData::Node;

   set_xml_meta(
        attributes=>['scheme','yt:term','label'],#default to []
        is_parent => 0, #default 1
        namespace_prefix => 'k', #default to ''
        tag_name  => 'category' # default to the package file name with the first letter in lower case
   );

   1;
   
   use WebService::GData::Node::Category();
   
   my $category = new WebService::GData::Node::Category('yt:term'=>'term');
      $category->yt_term('youtube term');
      
      "$category";#<k:category yt:term="youtube term"/>
           

IMPLEMENTED NODES

Many core nodes have already be implemented. You can look at their source directly to see their meta information. Although you may use this class and subclasses to implement other tags, most of the time they will be wrapped in the Feed packages and the end user shall not interact directly with them.

For reference, below is a list of all the tags implemented so far with their meta information (when it overwrites the default settings).

    APP                         #app: namespace
        - Control
        - Draft
        - Edited
    Author
    Category                    #attributes=>scheme term label
    Content                     #attributes=>src type
    GD                          #gd: namespace
       - Comments
       - FeedLink               #attributes=>rel href countHint,is_parent=>0
       - Rating                 #attributes=>min max numRaters average value,is_parent=>0
    GeoRSS #georss: namespace
       - Where
    GML                         #gml: namespace
       - Point                  #tag_name=>'Point'
       - Pos
    Link                        #attributes=>rel type href
    Media                       #media: namespace
       - Category               #attributes=>scheme label
       - Content                #attributes=>url type medium isDefault expression duration yt:format,is_parent=>0
       - Credit                 #attributes=>role yt:type scheme
       - Description            #attributes=>type
       - Group
       - Keywords
       - Player                 #attributes=>url
       - Rating                 #attributes=>scheme country
       - Restriction            #attributes=>type relationship
       - Thumbnail              #attributes=>url height width time, is_parent=>0
       - Title                  #attributes=>type
    Name
    Summary
    Title
    Uri
       

CAVEATS

• As the package push itself into your package when you use it, you must be aware when to change this behavior.

• All the methods installed in the package could conflict with a node name or its attributes.

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