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XML-EasyOBJ-1.10
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/ XML::EasyOBJ

NAME

XML::EasyOBJ - Easy XML object navigation

VERSION

Version 1.10

SYNOPSIS

# open exisiting file
my $doc = new XML::EasyOBJ('my_xml_document.xml');
my $doc = new XML::EasyOBJ(-type => 'file', -param => 'my_xml_document.xml');

# create new file
my $doc = new XML::EasyOBJ(-type => 'new', -param => 'root_tag');

# read from document
my $text = $doc->some_element($index)->getString;
my $attr = $doc->some_element($index)->getAttr('foo');
my $element = $doc->some_element($index);

# first "some_element" element
my $elements = $doc->some_element;
# list of "some_element" elements
my @elements = $doc->some_element;

# write to document
$doc->an_element->setString('some string')
$doc->an_element->addString('some string')
$doc->an_element->setAttr('attrname', 'val')

# access elements with non-name chars and the underlying DOM
my $element = $doc->getElement('foo-bar')->getElement('bar-none');
my $dom = $doc->foobar->getDomObj;

# remove elements/attrs
$doc->remElement('tagname', $index);
$doc->tag_name->remAttr($attr);

# remap builtin methods
$doc->remapMethod('getString', 's');
my $text = $doc->some_element->s;

DESCRIPTION

I wrote XML::EasyOBJ a couple of years ago because it seemed to me that the DOM wasn't very "perlish". The DOM is difficult to us mere mortals that don't use it on a regular basis. As I only need to process XML on an occasional basis I wanted an easy way to do what I needed to do without having to refer back to DOM documentation and UML class diagrams each time.

A quick fact list about XML::EasyOBJ:

* Runs on top of XML::DOM
* Allows access to the DOM as needed
* Simple routines to reading and writing elements/attributes

REQUIREMENTS

XML::EasyOBJ uses XML::DOM. XML::DOM is available from CPAN (www.cpan.org).

BEGINNER QUICK START GUIDE

Introduction

You too can write XML applications, just as long as you understand the basics of XML (elements and attributes). You can learn to write your first program that can read data from an XML file in a mere 10 minutes.

Assumptions

It is assumed that you are familiar with the structure of the document that you are reading. Next, you must know the basics of perl lists, loops, and how to call a function. You must also have an XML document to read.

Simple eh?

Loading the XML document

use XML::EasyOBJ;
my $doc = new XML::EasyOBJ('my_xml_document.xml') || die "Can't make object";

Replace the string "my_xml_document.xml" with the name of your XML document. If the document is in another directory you will need to specify the path to it as well.

The variable $doc is an object, and represents our root XML element in the document.

Reading text with getString

Each element becomes an object. So lets assume that the XML page looks like this:

<table>
 <record>
  <rec2 foo="bar">
   <field1>field1a</field1>
   <field2>field2b</field2>
   <field3>field3c</field3>
  </rec2>
  <rec2 foo="baz">
   <field1>field1d</field1>
   <field2>field2e</field2>
   <field3>field3f</field3>
  </rec2>
 </record>
</table>

As mentioned in he last step, the $doc object is the root element of the XML page. In this case the root element is the "table" element.

To read the text of any field is as easy as navigating the XML elements. For example, lets say that we want to retrieve the text "field2e". This text is in the "field2" element of the SECOND "rec2" element, which is in the FIRST "record" element.

So the code to print that value it looks like this:

print $doc->record(0)->rec2(1)->field2->getString;

The "getString" method returns the text within an element.

We can also break it down like this:

# grab the FIRST "record" element (index starts at 0)
my $record = $doc->record(0);

# grab the SECOND "rec2" element within $record
my $rec2 = $record->rec2(1);

# grab the "field2" element from $rec2
# NOTE: If you don't specify an index, the first item 
#       is returned and in this case there is only 1.
my $field2 = $rec2->field2;

# print the text
print $field2->getString;

Reading XML attributes with getAttr

Looking at the example in the previous step, can you guess what this code will print?

print $doc->record(0)->rec2(0)->getAttr('foo');
print $doc->record(0)->rec2(1)->getAttr('foo');

If you couldn't guess, they will print out the value of the "foo" attribute of the first and second rec2 elements.

Looping through elements

Lets take our example in the previous step where we printed the attribute values and rewrite it to use a loop. This will allow it to print all of the "foo" attributes no matter how many "rec2" elements we have.

foreach my $rec2 ( $doc->record(0)->rec2 ) {
  print $rec2->getAttr('foo');
}

When we call $doc->record(0)->rec2 this way (i.e. in list context), the module will return a list of "rec2" elements.

That's it!

You are now an XML programmer! *start rejoicing now*

PROGRAMMING NOTES

When creating a new instance of XML::EasyOBJ it will return an object reference on success, or undef on failure. Besides that, ALL methods will always return a value. This means that if you specify an element that does not exist, it will still return an object reference (and create that element automagically). This is just another way to lower the bar, and make this module easier to use.

You will run into problems if you have XML tags which are named after perl's special subroutine names (i.e. "DESTROY", "AUTOLOAD"), or if they are named after subroutines used in the module ( "getString", "getAttr", etc ). You can get around this by using the getElement() method of using the remapMethod() method which can be used on every object method (except AUTOLOAD and DESTROY).

AUTHOR/COPYRIGHT

Copyright (C) 2000-2002 Robert Hanson <rhanson@blast.net>

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

SEE ALSO

XML::DOM