PHP | XMLReader setRelaxNGSchemaSource() Function

Last Updated : 18 Mar, 2020

The XMLReader::setRelaxNGSchemaSource() function is an inbuilt function in PHP which is used to set the data containing a RelaxNG Schema to use for validation. The setRelaxNGSchemaSource() function is different from setRelaxNGSchema() function as the former accepts the rule as a string variable whereas later function accepts the rule as a .rng file.

Syntax:

bool XMLReader::setRelaxNGSchemaSource( string $source )

Parameters: This function accepts a single parameter $source which holds the string containing the RelaxNG Schema.

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

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

Example 1:

data.xml

<?xml version="1.0"?> 
<body> 
    <div> 
        <h1>GeeksForGeeks</h1> 
        <p>Portal for Geeks</p> 
    </div> 
    <div> 
        <h1>Heading 3</h1> 
        <p>Heading 4</p> 
    </div> 
</body> 

index.php

<?php 
  
// Create a new XMLReader instance 
$XMLReader = new XMLReader(); 
  
// Open the XML file 
$XMLReader->open('data.xml'); 
  
// Create rule as a string 
$RNG = "<element name=\"body\" 
xmlns=\"http://relaxng.org/ns/structure/1.0\"> 
<zeroOrMore> 
  <element name=\"div\"> 
    <element name=\"h1\"> 
      <text/> 
    </element> 
    <element name=\"p\"> 
      <text/> 
    </element> 
  </element> 
</zeroOrMore> 
</element>"; 
  
// Load the rule 
$XMLReader->setRelaxNGSchemaSource($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 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!

Example 2:

data.xml

<?xml version="1.0"?> 
<body> 
    <div> 
        <!--Create empty div element 
           to violate rule-->
    </div> 
    <div> 
        <h1>Heading 3</h1> 
        <h2>Heading 4</h2> 
    </div> 
</body> 

index.php

<?php 
  
// Create a new XMLReader instance 
$XMLReader = new XMLReader(); 
  
// Open the XML file 
$XMLReader->open('data.xml'); 
  
// Create rule as a string 
$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>"; 
  
// Load the rule 
$XMLReader->setRelaxNGSchemaSource($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!

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

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