PHP | XMLReader setRelaxNGSchema() Function

Last Updated : 18 Mar, 2020

The XMLReader::setRelaxNGSchema() function is an inbuilt function in PHP which is used to set the filename or URI for the RelaxNG Schema to use for validation.

Syntax:

bool XMLReader::setRelaxNGSchema( string $filename )

Parameters: This function accepts a single parameter $filename which holds the filename or URI pointing to a RelaxNG Schema.

Return Value: This function returns TRUE on success or FALSE on failure.

Below examples illustrate the XMLReader::setRelaxNGSchema() function in PHP:

Example 1:

data.xml ( The XML file to be validated )

<?xml version="1.0"?> 
<body> 
    <div> 
        <h1>Heading 1</h1> 
        <h2>Heading 2</h2> 
    </div> 
    <div> 
        <h1>Heading 3</h1> 
        <h2>Heading 4</h2> 
    </div> 
</body> 

rule.rng ( The rules to be followed by the XML file )

<element name="body" 
  xmlns="http://relaxng.org/ns/structure/1.0"> 
  <zeroOrMore> 
    <element name="div"> 
      <element name="h1"> 
        <text/> 
      </element> 
      <element name="h2"> 
        <text/> 
      </element> 
    </element> 
  </zeroOrMore> 
</element> 

index.php ( PHP script to run the validator )

<?php 
  
// Create a new XMLReader instance 
$XMLReader = new XMLReader(); 
  
// Open the XML file 
$XMLReader->open('data.xml'); 
  
// Load the rule file 
$XMLReader->setRelaxNGSchema('rule.rng'); 
  
// Iterate through the XML nodes 
// and validate each node 
while ($XMLReader->read()) { 
    if ($XMLReader->nodeType == XMLREADER::ELEMENT) { 
  
        // Check if XML follows the relaxNG rule 
        if ($XMLReader->isValid()) { 
            echo "This document is valid!<br>"; 
        } 
  
    } 
} 
?> 

Output:

This document is valid!
This document is valid!
This document is valid!
This document is valid!
This document is valid!
This document is valid!
This document is valid!

Program 2:

data.xml

<?xml version="1.0"?> 
<body> 
    <div> 
        <!--Remove Heading 1 
          to violate rule-->
        <h2>Heading 2</h2> 
    </div> 
    <div> 
        <h1>Heading 3</h1> 
        <h2>Heading 4</h2> 
    </div> 
</body> 

rule.rng

<element name="body"
  xmlns="http://relaxng.org/ns/structure/1.0"> 
  <zeroOrMore> 
    <element name="div"> 
      <element name="h1"> 
        <text/> 
      </element> 
      <element name="h2"> 
        <text/> 
      </element> 
    </element> 
  </zeroOrMore> 
</element> 

index.php

<?php 
  
// Create a new XMLReader instance 
$XMLReader = new XMLReader(); 
  
// Open the XML file 
$XMLReader->open('data.xml'); 
  
// Load the rule file 
$XMLReader->setRelaxNGSchema('rule.rng'); 
  
// Iterate through the XML nodes 
while ($XMLReader->read()) { 
    if ($XMLReader->nodeType == XMLREADER::ELEMENT) { 
  
        // Check if XML follows the relaxNG rule 
        if (!$XMLReader->isValid()) { 
            echo "This document is not valid!<br>"; 
        } 
  
    } 
} 
?> 

Output:

This document is not valid!
This document is not valid!
This document is not valid!
This document is not valid!

Reference: https://www.php.net/manual/en/xmlreader.setrelaxngschema.php

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