PHP | DOMDocument relaxNGValidate() Function

The DOMDocument::relaxNGValidate() function is an inbuilt function in PHP which is used to performs relaxNG validation on the document. The relaxNG is an alternative to DDT and defines a structure which needs to be followed by the XML document.

Syntax:

bool DOMDocument::relaxNGValidate( string $filename )

Parameters: This function accepts a single parameter $filename which holds the RNG file.

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

Below given programs illustrate the DOMDocument::relaxNGValidate() function in PHP:

Program 1:

• File name: rule.rng

  <element name="college"
    xmlns="http://relaxng.org/ns/structure/1.0">
    <zeroOrMore>
      <element name="rollno">
        <element name="name">
          <text/>
        </element>
        <element name="subject">
          <text/>
        </element>
      </element>
    </zeroOrMore>
  </element>
• File name: index.php

  <?php
  
  // Create a new DOMDocument
  $doc = new DOMDocument;
  
  // Load the XML
  $doc->loadXML("<?xml version=\"1.0\"?>
  <college>
    <rollno>
      <name>John Smith</name>
      <subject>Web</subject>
    </rollno>
    <rollno>
      <name>John Doe</name>
      <subject>CSE</subject>
    </rollno>
  </college>");
  
  // Check if XML follows the relaxNG rule
  if ($doc->relaxNGValidate('rule.rng')) {
      echo "This document is valid!\n";
  }
  ?>
• Output:

  This document is valid!

Program 2:

• File name: rule.rng

  <element name="company"
    xmlns="http://relaxng.org/ns/structure/1.0">
    <zeroOrMore>
      <element name="employee">
        <element name="name">
          <text/>
        </element>
        <element name="salary">
          <text/>
        </element>
      </element>
    </zeroOrMore>
  </element>
• File name: index.php

  <?php
  
  // Create a new DOMDocument
  $doc = new DOMDocument;
  
  // Load the XML
  $doc->loadXML("<?xml version=\"1.0\"?>
  <company>
    <employee>
      <name>John Smith</name>
      <salary>Web</salary>
    </employee>
    <employee>
      <!-- Do not add salary to voilate rule -->
      <name>John Doe</name>
    </employee>
  </company>");
  
  // Check if XML doesn't follows the relaxNG rule
  if (!$doc->relaxNGValidate('rule.rng')) {
      echo "This document is not valid!\n";
  }
  ?>
• Output:

  This document is not valid!

Reference: https://www.php.net/manual/en/domdocument.relaxngvalidate.php