NAME
XML::Rabbit - Consume XML with Moose and xpath queries
VERSION
version 0.3.0
SYNOPSIS
my $xhtml = W3C::XHTML->new( file => 'index.xhtml' );
print "Title: " . $xhtml->title . "\n";
print "First image source: " . $xhtml->body->images->[0]->src . "\n";
exit;
package W3C::XHTML;
use XML::Rabbit::Root;
add_xpath_namespace 'xhtml' => 'http://www.w3.org/1999/xhtml';
has_xpath_value 'title' => '/xhtml:html/xhtml:head/xhtml:title';
has_xpath_object 'body' => '/xhtml:html/xhtml:body' => 'W3C::XHTML::Body';
has_xpath_object_list 'all_anchors_and_images' => '//xhtml:a|//xhtml:img',
{
'xhtml:a' => 'W3C::XHTML::Anchor',
'xhtml:img' => 'W3C::XHTML::Image',
},
;
finalize_class();
package W3C::XHTML::Body;
use XML::Rabbit;
has_xpath_object_list 'images' => './/xhtml:img' => 'W3C::XHTML::Image';
finalize_class();
package W3C::XHTML::Image;
use XML::Rabbit;
has_xpath_value 'src' => './@src';
has_xpath_value 'alt' => './@alt';
has_xpath_value 'title' => './@title';
finalize_class();
package W3C::XHTML::Anchor;
use XML::Rabbit;
has_xpath_value 'href' => './@src';
has_xpath_value 'title' => './@title';
finalize_class();
DESCRIPTION
XML::Rabbit is a Moose-based class construction toolkit you can use to
make XPath-based XML extractors with very little code. Each attribute in
your class created with the above helper function is linked to an XPath
query that is executed on your XML document when you request the value.
Creating object hierarchies that mimic the layout of the XML document is
almost as easy as doing a search and replace on the XML DTD (if you have
one).
You can return multiple values from the XML either as arrays or hashes,
depending on how you need to work with the data from the XML document.
The example in the synopsis shows how to create a class hierarchy that
enables easy retrival of certain information from an XHTML document.
Also notice that if you specify an xpath query that can return multiple
XML elements, you need to specify a hash map (xml tag => class name)
instead of just specifying the class name returned.
All the array and hash-returning attributes are tagged with the Array
and Hash native traits, so it is quick and easy to specify additional
delegations. All the "has_xpath_value*" helpers expect the value to be
of a "Str" type constraint. Array and hash-returning attributes
automatically set their isa to "ArrayRef[Str]" and "HashRef[Str]"
respectively.
All the helper methods and their associated arguments are explained in
XML::Rabbit::Sugar detail.
Be aware that if your XML document contains a default XML namespace
(like XHTML does), you MUST specify it with "add_xpath_namespace()", or
else your xpath queries will not match anything. The XML document is not
scanned for XML namespaces during initialization.
FUNCTIONS
import
Automatically loads namespace::autoclean into the caller's package and
dispatches to "import" in XML::Rabbit::Sugar (tail call).
unimport
Dispatches to "unimport" in XML::Rabbit::Sugar (tail call).
init_meta
Initializes the metaclass of the calling class and adds the role
XML::Rabbit::Node.
IMPORTS
When you specify "use XML::Rabbit::Root" (or "use XML::Rabbit" in child
nodes) you do the equivalent of the following code:
use Moose;
with "XML::Rabbit::RootNode"; # if you use XML::Rabbit::Root
with "XML::Rabbit::Node"; # if you use XML::Rabbit
use namespace::autoclean;
use XML::Rabbit::Sugar;
This ensures that you don't have to specify "no Moose" at the end of
your code to clean up imported functions you have used in your class.
The "finalize_class()" call at the end of the file is the same as
writing the following piece of code:
__PACKAGE__->meta->make_immutable();
1;
This optimizes the class and ensures it always returns a true value,
which is required to successfully load a Perl script file.
TECHNICAL DETAILS
The trait applied to the attribute will wrap the type constraint union
in an ArrayRef if the trait name is XPathObjectList and as a HashRef if
the trait name is XPathObjectMap. As all the traits that end with List
return array references, their "isa" must be an ArrayRef. The same is
valid for the *Map traits, just that they return HashRef instead of
ArrayRef.
The namespace prefix used in "isa_map" MUST be specified in the
"namespace_map". If a prefix is used in "isa_map" without a
corresponding entry in "namespace_map" an exception will be thrown.
CAVEATS
Be aware of the syntax of XPath when used with namespaces. You should
almost always define "namespace_map" when dealing with XML that use
namespaces. Namespaces explicitly declared in the XML are usable with
the prefix specified in the XML (except if you use "isa_map"). Be aware
that a prefix must usually be declared for the default namespace
(xmlns=...) to be able to use it in XPath queries. See the example above
(on XHTML) for details. See "findnodes" in XML::LibXML::Node for more
information.
Because XML::Rabbit uses XML::LibXML's DOM parser it is limited to
handling XML documents that can fit in available memory. Unfortunately
there is no easy way around this, because XPath queries need to work on
a tree model, and I am not aware of any way of doing that without
keeping the document in memory. Luckily XML::LibXML's DOM implementation
is written in C, so it should use much less memory than a pure Perl DOM
parser.
SEMANTIC VERSIONING
This module uses semantic versioning concepts from <http://semver.org/>.
ACKNOWLEDGEMENTS
The following people have helped to review or otherwise encourage me to
work on this module.
Chris Prather (perigrin)
Matt S. Trout (mst)
Stevan Little (stevan)
SEE ALSO
* Moose
* XML::LibXML
* namespace::autoclean
* XML::Toolkit
* XML::Twig
* Mojo::DOM
* XPath tutorial <http://zvon.org/comp/r/tut-XPath_1.html>
* XPath Specification <http://www.w3.org/TR/xpath/>
* Implementing WWW::LastFM, a client library to the Last.FM API, with
XML::Rabbit
<http://blog.robin.smidsrod.no/2011/09/30/implementing-www-lastfm-pa
rt-1>
SUPPORT
Perldoc
You can find documentation for this module with the perldoc command.
perldoc XML::Rabbit
Websites
The following websites have more information about this module, and may
be of help to you. As always, in addition to those websites please use
your favorite search engine to discover more resources.
* MetaCPAN
A modern, open-source CPAN search engine, useful to view POD in HTML
format.
<http://metacpan.org/release/XML-Rabbit>
* Search CPAN
The default CPAN search engine, useful to view POD in HTML format.
<http://search.cpan.org/dist/XML-Rabbit>
* RT: CPAN's Bug Tracker
The RT ( Request Tracker ) website is the default bug/issue tracking
system for CPAN.
<http://rt.cpan.org/NoAuth/Bugs.html?Dist=XML-Rabbit>
* AnnoCPAN
The AnnoCPAN is a website that allows community annotations of Perl
module documentation.
<http://annocpan.org/dist/XML-Rabbit>
* CPAN Ratings
The CPAN Ratings is a website that allows community ratings and
reviews of Perl modules.
<http://cpanratings.perl.org/d/XML-Rabbit>
* CPAN Forum
The CPAN Forum is a web forum for discussing Perl modules.
<http://cpanforum.com/dist/XML-Rabbit>
* CPANTS
The CPANTS is a website that analyzes the Kwalitee ( code metrics )
of a distribution.
<http://cpants.perl.org/dist/overview/XML-Rabbit>
* CPAN Testers
The CPAN Testers is a network of smokers who run automated tests on
uploaded CPAN distributions.
<http://www.cpantesters.org/distro/X/XML-Rabbit>
* CPAN Testers Matrix
The CPAN Testers Matrix is a website that provides a visual overview
of the test results for a distribution on various Perls/platforms.
<http://matrix.cpantesters.org/?dist=XML-Rabbit>
* CPAN Testers Dependencies
The CPAN Testers Dependencies is a website that shows a chart of the
test results of all dependencies for a distribution.
<http://deps.cpantesters.org/?module=XML::Rabbit>
Bugs / Feature Requests
Please report any bugs or feature requests by email to "bug-xml-rabbit
at rt.cpan.org", or through the web interface at
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=XML-Rabbit>. You will be
automatically notified of any progress on the request by the system.
Source Code
The code is open to the world, and available for you to hack on. Please
feel free to browse it and play with it, or whatever. If you want to
contribute patches, please send me a diff or prod me to pull from your
repository :)
<http://github.com/robinsmidsrod/XML-Rabbit>
git clone git://github.com/robinsmidsrod/XML-Rabbit.git
AUTHOR
Robin Smidsrød <robin@smidsrod.no>
COPYRIGHT AND LICENSE
This software is copyright (c) 2013 by Robin Smidsrød.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.