The London Perl and Raku Workshop takes place on 26th Oct 2024. If your company depends on Perl, please consider sponsoring and/or attending.
 / 
XML-EasyOBJ-0.01
River stage zero No dependents
/ XML::EasyOBJ

NAME

XML::EasyOBJ - Easy XML object navigation

VERSION

Version 1.0

SYNOPSIS

# create the object
my $doc = new XML::EasyOBJ('my_xml_document.xml');

# print some text from the document
print $doc->some_element(1)->getString;

# print an attribute value
print $doc->some_element(0)->getAttr('foo')."\n";

# iterate over a list of elements
foreach my $x ( $foo->some_element ) {
  print $x->getString."\n";
  }

DESCRIPTION

XML::EasyOBJ lets you take an XML page and essentially create an object out of it. Each element becomes a method, which makes it really easy to navigate an XML page (if you know the structure). The motivation behind this module was to create an interface so simple that anyone who knows the basic functionality of Perl can learn how to read data from an XML document in less than 10 minutes (well, that and the fact that my modules haven't been mentioned in TPJ yet, and maybe this one will :).

This module is also a time saver even if you are familiar with the other modules available, but want something simple so that you can throw together a script in a few minutes (unless of course you know the DOM like the back of your hand).

REQUIREMENTS

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

QUICK START GUIDE

Introduction

Even if you have never used any XML module, just as long as you understand the basics of XML (elements and attributes), you can learn to write a program that can read data from an XML file in 10 minutes. ...Well maybe 30 minutes if you are a slow reader like I am.

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?

$doc->record(0)->rec2(0)->getAttr('foo');
$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, 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. 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 (ie "DESTROY", "AUTOLOAD"), or if they are named after subroutines used in the module ( "getString", "getAttr", "_extractText", and "new" ).

AUTHOR/COPYWRITE

Robert Hanson (rhanson@blast.net)

Copyright 2000, Robert Hanson. All rights reserved.

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

SEE ALSO

XML::DOM