PHP XML Tutorial: Create, Parse, Read with Example What is XML?

XML parser

An XML parser is a software library or package of that provided interfaces for client application to work with an XML document. The XML parser is designed to read the XML and create a way for programs to use XML.

XML parser validates the document and check that the document is well formatted. Let’s understand the working of XML parser by the figure below

<?php
   $data = "<?xml version = '1.0' encoding = 'UTF-8'?>
   
   <note>
      <Course>Android</Course>
      <Subject>Android</Subject>
      <Company>cotocus</Company>
      <Price>$10</Price>
   </note>";
   
   $xml = simplexml_load_string($data) or die("Error: Cannot create object");
?>
<html>

   <head>
      <body>
         
         <?php
            print_r($xml);
         ?>
      
      </body>
   </head>
   
</html>

In PHP there are two major types of XML parsers:

Tree-Based Parsers
Event-Based Parsers

Tree-based parsers holds the entire document in Memory and transforms the XML document into a Tree structure. It analyzes the whole document, and provides access to the Tree elements (DOM).

DOM (Document object Model)

A DOM document is an object which contains all the document of an XML document is composed like a tree structure. The DOM parser implement a DOM API is very simple to use.

Feature of DOM parser

DOM parser create an internal structure in memory which is a DOM document object and client applications get information of the original XML document by invoking method on the document object DOM parser has a tree based

Event-Based Parsers

Event-based parsers do not hold the entire document in Memory, instead, they read in one node at a time and allow you to interact with in real time. Once you move onto the next node, the old one is thrown away.

Example of event-based parsers:

XMLReader
XML Expat Parser

Read XML Elements in php

<?xml version="1.0"?>
<company>
 <employee>
 <firstname>Abhishek </firstname>
 <lastname>singh</lastname>
 <designation>php developers</designation>
 <salary>200000</salary>
 </employee>
 <employee>
 <firstname>Abhijeet </firstname>
 <lastname>singh</lastname>
 <designation>.net developers</designation>
 <salary>250000</salary>
 </employee>
</company>

In your PHP program, use the simplexml_load_file function to load an external XML file and create an object. After that, you can access any element from XML

<?php
  $xmldata = simplexml_load_file("employees.xml") or die("Failed to load");
  echo $data->employee[0]->firstname . "<\n>";
  echo $data->employee[1]->firstname;
?>

Output:
Abhishek
Abhijeet

How to Create an XML document using PHP

<?Php
$xml =new DOMDocument ("1.8");
$root=$xml->createElement("data");
$xml->apppendChild($root);

$id=$xml->createElement("id");
$idText=$xml->createTextNode(","):
$id->appendchild($idText);

$title=$xml->createElement("title");
$titletext=$xml->createTextNode("Xml PHP Demo")
$title->appendChild($titleText);

$book= $ml->createElement("book");
$book= $appendChild(id);
$book = appendChild($title); 

$root = appendChild($book);

$xml->fromatOutput=true;
echo <xmp>.$xml->saveXML()."</xmp>";
$xml->save('notes.xml') or die ('error');

?>

Output:
<data>
<book>
<id>1</id>
<title>"XML PHP DEMO"</title>
</book>
</data>

XML Document Example

 <employee>
 <firstname>Abhishek </firstname>
 <lastname>singh</lastname>
 <designation>php developers</designation>
 <salary>200000</salary>
<sec>
 <firstname>Abhijeet </firstname>
 <lastname>singh</lastname>
 <designation>.net developers</designation>
 <salary>250000</salary>
 </employee>

Why use XML?

NO page Reloading on each request
updated a part page not full page
send Data to server in background
Receive Data from server in background
Better user experience
Improves speed and performance

Inheritance:

Accessing the features of one class from another class.
Inheritance allows you to write the code in the parent class and use it in both parent and child classes.
The parent class is also called a base class or super class. And the child class is also known as a derived class or a subclass.

Declaration of super Class :

class SuperClassName extends DerivedClassName
{
members of Super class
};

Type of Inheritance in php:

Single Inheritance
Multi-level Inheritance
Hierarchical Inheritance

Polymorphism

Polymorphism means “many forms”, and it occurs when we have many classes that are related to each other by inheritance

Real life example of polymorphism: A person at the same time can have different characteristics. Like a man at the same time is a father, a husband, an employee. So the same person possesses different behavior in different situations. This is called polymorphism.

Example of Polymorphism:

<?php

class base

{

function add($a,$b)

{

$res=$a*$b;

echo "Multiplication = ".$res;

}

}


class child extends base

{

function add($a,$b)

{

$res=$a+$b;

echo "Sum  = ".$res;

}

}

 $obj= new child();

 $obj->add(1000,500);
 
?>

Output:
Sum = 1500