PHP | XMLReader setSchema() Function

The XMLReader::setSchema() function is an inbuilt function in PHP which is used to validate the document using a XSD schema. This XSD schema is nothing but a file that defines the rule for the XML structure and should be in the form of .xsd file.

Syntax:

bool XMLReader::setSchema( string $filename )

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

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

Exceptions: This function throws E_WARNING if libxml extension was compiled without schema support.

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

Example 1:

• data.xml ( The XML file to be validated )

  
  

  
  
  

  <?xml version="1.0"?> <student>     <name>Rahul</name>     <rollno>1726262</rollno> </student>

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

  
  

  
  
  

  <?xml version="1.0"?> <xs:schema xmlns:xs=       "http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">     <xs:element name="student">         <xs:complexType>             <xs:sequence>                 <xs:element name="name"                     type="xs:string"/>                 <xs:element name="rollno"                    type="xs:integer"/>             </xs:sequence>         </xs:complexType>     </xs:element> </xs:schema>

• index.php ( The PHP script to run the validation )

  
  

  
  
  

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

• Output:

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

Example 2:

• data.xml

  
  

  
  
  

  <?xml version="1.0"?> <div>     <phoneNo>This should not be text</phoneNo> </div>

• rule.xsd

  
  

  
  
  

  <?xml version="1.0"?> <xs:schema xmlns:xs=       "http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">     <xs:element name="div">         <xs:complexType>             <xs:sequence>                 <xs:element name="phoneNo"                    type="xs:integer"/>             </xs:sequence>         </xs:complexType>     </xs:element> </xs:schema>

• index.php

  
  

  
  
  

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

• Output:

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

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