Xml_set_external_entity_ref_handler()

The xml_set_external_entity_ref_handler() function is a PHP built-in function that sets a user-defined function as the handler for external entity references in an XML parser. When parsing XML files using the SimpleXML library or other XML parsing libraries in PHP, the xml_set_external_entity_ref_handler() function is used to set a custom function to handle external entity references.

The xml_set_external_entity_ref_handler() function is useful when you need to handle external entities referenced in an XML file, for example, to load external data from a database or perform other actions.

Syntax

The syntax of the xml_set_external_entity_ref_handler() function is as follows:

xml_set_external_entity_ref_handler($parser, $handler)

Where $parser is the XML parser on which the handler is set, and $handler is the name of the user-defined function that will handle external entity references.

Usage Examples

Let's take a look at a practical example of using xml_set_external_entity_ref_handler() in PHP.

Example: Setting an External Entity Reference Handler Function

Suppose you have an XML file "data.xml" that you want to parse using the SimpleXML library in PHP. You can use the xml_parser_create() function to create a new XML parser, and then set an external entity reference handler function using the xml_set_external_entity_ref_handler() function, like this:

function handle_external_entity_ref($parser, $open_entity_names, $base, $system_id, $public_id) {
    // do something with the external entity reference
}

$xml_parser = xml_parser_create();
xml_set_external_entity_ref_handler($xml_parser, "handle_external_entity_ref");

This code creates a new XML parser using xml_parser_create(). It then sets a custom function "handle_external_entity_ref()" to handle external entity references in the XML file. This function can load external data from a database or perform any other necessary actions.

Conclusion

In this article, we've discussed PHP's xml_set_external_entity_ref_handler() function and how it can be used to set an external entity reference handler function for an XML parser in PHP. We've explained what the function does, its syntax, and provided an example of how it can be used in a practical scenario. By using xml_set_external_entity_ref_handler() in your PHP applications, you can handle external entities referenced in an XML file and perform any necessary actions on the external data.