/ 
XML-API-0.12
River stage one • 1 direct dependent • 1 total dependent
/ XML::API

NAME

XML::API - Perl extension for creating XML documents

SYNOPSIS

use XML::API;
my $x = XML::API->new(doctype => 'xhtml');

$x->html_open();
$x->head_open();
$x->title('Test Page');
$x->head_close();
$x->body_open();
$x->div_open(-id => 'content');
$x->p(-class => 'test', 'A test paragraph');
$x->div_close();
$x->body_close();
$x->html_close();

$x->_print;

Will produce this nice output:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict...>
<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <title>Test Page</title>
  </head>
  <body>
    <div id="content">
      <p class="test">A test paragraph</p>
    </div>
  </body>
</html>

DESCRIPTION

XML::API is a class for creating XML documents using object method calls. This class is meant for generating XML programatically and not for reading or parsing it.

A document author calls the desired methods (representing elements) to create an XML tree in memory which can then be rendered or saved as desired. The advantage of having the in-memory tree is that you can be very flexible about when different parts of the document are created and the final output is always nicely rendered.

TUTORIAL

The first step is to create an object. The 'doctype' attribute is mandatory. Known values (ie - distributed with XML::API) are 'xhtml' and 'rss'. The encoding is not mandatory and will default to 'UTF-8'.

use XML::API;
my $x = XML::API->new(doctype => 'xhtml', encoding => 'UTF-8');

$x is the only object we need for our entire XHTML document. It starts out empty so we want to open up the html element:

$x->html_open;

Because we have called a *_open() function the 'current' or 'containing' element is now 'html'. All further elements will be added inside the 'html' element. So lets add head and title elements and the title content ('Document Title') to our object:

$x->head_open;
$x->title('Document Title');

The 'title()' method on its own (ie not 'title_open()') indicates that we are specifiying the entire title element. Further method calls will continue to place elements inside the 'head' element until we specifiy we want to move on by calling the _close method:

$x->head_close();

This sets the current element back to 'html'.

So, basic elements seem relatively easy. How do we create elements with attributes? When either the element() or element_open() methods are called with a hashref argument the keys and values of the hashref become the attributes:

$x->body_open({id => 'bodyid'}, 'Content', 'more content');

or if you want, you can also use CGI-style attributes which I prefer because it takes less typing:

$x->body_open(-id => 'bodyid', 'Content', 'more content');

By the way, both the element() and element_open() methods take arbitrary numbers of content arguments as shown above. However if you don't want to specify the content of the element at the time you open it up you can use the _add() utility method later on:

$x->div_open();
$x->_add('Content added after the _open');

The final thing is to close out the elements and render the docment.

$x->div_close();
$x->body_close();
print $x->_as_string();

Because we are not adding any more elements or content it is not strictly necessary to close out all elements, but consider it good practice.

You can add XML::API object to other objects, which lets you create for instance the head and body parts separately, and just bring them all together just before printing:

my $h = XML::API::XHTML->new();
$h->head_open
...
my $x = XML::API::XHTML->new();
$x->html_open;
$x->_add($h);
$x->html_close;
$x->_print;

Note that it is also possible to call the XML::API::<doctype> class directly.

CLASS SUBROUTINES

new

Takes the following arguments:

doctype  => '(xhtml|rss|WIX2)' # Mandatory
encoding => 'xxx'              # Optional
debug    => 1|0                # Optional

Create a new XML::API based object. What you get back is actually an object of type XML::API::<doctype> which is derived from XML::API. The object is initialized as empty - ie contains no elements.

You can also call XML::API::XHTML->new() directly and omit the doctype.

CONTENT

$x->element_open(-attribute => $value, {attr2 => 'val2'}, $content)

Add a new element to the 'current' element, and set the current element to be the element just created. Returns a reference (private data type) to the new element which can be used in the _goto function below.

Ie given that $x currently represents:

<html>  <---- 'current' element
        <---- future elements/content goes here
</html>

then $x->head_open(-attribute => $value) means the tree is now:

<html>
  <head attribute="$value">  <---- 'current' element
                             <---- future elements/content goes here
  </head>
</html>

$x->_add($content)

Add $content to the 'current' element. $content can be either scalar (in which case the characters '<&">' will be escaped) or another XML::API object. This method will die if you attempt to add $x to itself or if $x does not have a current element.

$x->_raw($content)

Adds unescaped content to the 'current' element. You need to be careful of characters that mean something in XML such as '<','&' and '>'. This method will die if $content is an XML::API derivative or if $x does not have a current element.

$x->element_close( )

This does not actually modify the tree but simply tells the object that future elements will be added to the parent of the current element. Ie given that $x currently represents:

<div>
  <p>  <---- 'current' element
    $content
         <---- future elements/content goes here
  </p>
</div>

then $x->p_close() means the tree is now:

<div>    <---- 'current' element
  <p>
    $content
  </p>
         <---- future elements go here
</div>

If you try to call a _close() method that doesn't match the current element a warning will be issued and the call will fail.

$x->element(-attribute => $value, {attr2 => 'val2'}, $content)

Add a new element to the 'current' element but keep the 'current' element the same. Returns a reference (private data type) to the new element which can be used in the _goto function below.

This is effectively the same as the following:

$x->element_open(-attribute => $value, -attr2=>'val2');
$x->_add($content);
$x->element_close;

If $content is not given (or never added with the _add method) for an element then it will be rendered as empty. Ie, $x->br() produces:

<br />

$x->_comment($comment)

Add an XML comment to $x. Is almost the same as this:

$x->_raw("\n<!--");
$x->_add($content);
$x->_raw('-->')

Except that indentation is correct. Any occurences of '--' in $content will be replaced with '- -'.

$x->_cdata($content)

A shortcut for $x->_raw("\n<![CDATA[", $content, " ]]>");

$x->_javascript($script )

A shortcut for adding $script inside a pair of <script type="text/javascript"> elements and a _CDATA tag.

$x->_parse($content)

Adds content to the current element, but will parse it for xml elements and add them as method calls. Regardless of $content (missing end tags etc) the current element will remain the same.

Make sure that your encoding is correct before making this call as it will be passed as such to XML::Parser::Expat.

$x->_attrs( )

Allows you to get/set the attributes of the current element. Accepts and returns and hashref.

META DATA

$x->_encoding($value)

Set the encoding definition produced in the xml declaration. Returns the current value if called without an argument. This is an alternative to defining the encoding in the call to 'new'.

The XML encoding definition for objects is determined by the following, in this order:

* the last call to _encoding
* the encoding parameter given at object creation
* $XML::API::ENCODING, set by your script before calling new
* UTF-8, the package default

If you _add one object to another with different encodings the top-level object's definition will be used.

$x->_debug(1|0)

Turn on|off debugging from this point onwards. Debugging appears as xml comments in the rendered XML output.

$x->_current( )

Returns a reference (private data type) to the current element. Can be used in the _goto method to get back to the current element in the future.

$x->_set_id($id)

Set an identifier for the current element. You can then use the value of $id in the _goto() method.

$x->_goto($id)

Change the 'current' element. $id is a value which has been previously used in the _set_id() method, or the return value of a _current() call.

This is useful if you create the basic structure of your document, but then later want to go back and modify it or fill in the details.

OUTPUT

$x->_as_string( )

Returns the xml-rendered version of the object. The xml is cached unless the object is modified so this can be called mulitple times in a row with little cost.

$x->_fast_string( )

Returns the rendered version of the XML document without newlines or indentation.

$x->_print( )

A shortcut for "print $x->_as_string()". The "" operator is also overloaded so it is in fact possible to simply 'print $x' as well.

COMPATABILITY

Since version 0.10 a call to new() does not automatically add the root element to the object. If it did so you wouldn't be able to add one object to another.

SEE ALSO

XML::API was written for the Rekudos framework: http://rekudos.net/

AUTHOR

Mark Lawrence <nomad@null.net>

A small request: if you use this module I would appreciate hearing about it.

COPYRIGHT AND LICENSE

Copyright (C) 2004-2007 Mark Lawrence <nomad@null.net>

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.