register_deactivation_hook() │ WP 2.0.0

Registers a function that will be executed after the plugin is deactivated.

Hooks the function specified in the second parameter to the action deactivate_PLUGINNAME. This action is triggered when the plugin is deactivated.

Here PLUGINNAME is the name of the plugin:

For example, if the plugin is located in wp-content/plugins/sampleplugin/sample.php, then the hook name will be: deactivate_sampleplugin/sample.php.
If the plugin consists of a single file wp-content/plugins/sample.php, then the hook name will be: deactivate_sample.php.

No Hooks.

Returns

null. Does not return anything.

Usage

register_deactivation_hook( $file, $function );

$file(string) (required): Path to the main plugin file in the wp-content/plugins directory. You can specify the full path. Usually, the magic constant __FILE__ is used.
$function(string/array) (required): The name of the callback function that will be executed upon deactivation of the plugin.

Examples

#1 Running the function when the plugin is deactivated

Suppose the function we need to run when deactivating the plugin is called myplugin_deactivate() and it is located in the main plugin file:

wp-content/plugins/myplugin.php
or
wp-content/plugins/myplugin/myplugin.php

Then, use this code to call the deactivate function:

register_deactivation_hook( __FILE__, 'myplugin_deactivate' );

function myplugin_deactivate(){
	// do what you need to do when you deactivate the plugin.
}

This (string) will call function myplugin_deactivate() when the plugin is deactivated.

#2 Normal functions (not classes)

This demo shows how to call the Activate/Deactivate/Delete functions in a plugin file:

<?php
defined( 'ABSPATH' ) OR exit;

/**
 * Plugin Name: (WCM) Activate/Deactivate/Uninstall - Functions
 * Description: Example Plugin to show activation/deactivation/uninstall callbacks for plain functions.
 * Author:      Franz Josef Kaiser/wecodemore
 * Author URL:  http://unserkaiser.com
 * Plugin URL:  http://wordpress.stackexchange.com/questions/25910/uninstall-activate-deactivate-a-plugin-typical-features-how-to/25979#25979
 */

register_activation_hook(   __FILE__, 'WCM_Setup_Demo_on_activation' );
register_deactivation_hook( __FILE__, 'WCM_Setup_Demo_on_deactivation' );
register_uninstall_hook(    __FILE__, 'WCM_Setup_Demo_on_uninstall' );

function WCM_Setup_Demo_on_activation()
{
	if ( ! current_user_can( 'activate_plugins' ) )
		return;
	$plugin = isset( $_REQUEST['plugin'] ) ? $_REQUEST['plugin'] : '';
	check_admin_referer( "activate-plugin_{$plugin}" );

	// Uncomment this line to see the function in action
	// exit( var_dump( $_GET ) );
}

function WCM_Setup_Demo_on_deactivation()
{
	if ( ! current_user_can( 'activate_plugins' ) )
		return;
	$plugin = isset( $_REQUEST['plugin'] ) ? $_REQUEST['plugin'] : '';
	check_admin_referer( "deactivate-plugin_{$plugin}" );

	// Uncomment this line to see the function in action
	// exit( var_dump( $_GET ) );
}

function WCM_Setup_Demo_on_uninstall()
{
	if ( ! current_user_can( 'activate_plugins' ) )
		return;
	check_admin_referer( 'bulk-plugins' );

	// Important: check if this is the file that
	// was registered in the process of the deletion hook.
	if ( __FILE__ != WP_UNINSTALL_PLUGIN )
		return;

	// Uncomment this line to see the function in action
	// exit( var_dump( $_GET ) );
}

#3 Architecture for OOP (PHP classes)

If the plugin is written as a PHP class, the functions must be connected as follows:

<?php
defined( 'ABSPATH' ) OR exit;
/**
 * Plugin Name: (WCM) Activate/Deactivate/Uninstall - CLASS
 * Description: Example Plugin to show activation/deactivation/uninstall callbacks for classes/objects.
 * Author:      Franz Josef Kaiser/wecodemore
 * Author URL:  http://unserkaiser.com
 * Plugin URL:  http://wordpress.stackexchange.com/questions/25910/uninstall-activate-deactivate-a-plugin-typical-features-how-to/25979#25979
 */

register_activation_hook(   __FILE__, array( 'WCM_Setup_Demo_Class', 'on_activation' ) );
register_deactivation_hook( __FILE__, array( 'WCM_Setup_Demo_Class', 'on_deactivation' ) );
register_uninstall_hook(    __FILE__, array( 'WCM_Setup_Demo_Class', 'on_uninstall' ) );

add_action( 'plugins_loaded', array( 'WCM_Setup_Demo_Class', 'init' ) );
class WCM_Setup_Demo_Class
{
	protected static $instance;

	public static function init()
	{
		is_null( self::$instance ) AND self::$instance = new self;
		return self::$instance;
	}

	public static function on_activation()
	{
		if ( ! current_user_can( 'activate_plugins' ) )
			return;
		$plugin = isset( $_REQUEST['plugin'] ) ? $_REQUEST['plugin'] : '';
		check_admin_referer( "activate-plugin_{$plugin}" );

		// Uncomment this line to see the function in action
		// exit( var_dump( $_GET ) );
	}

	public static function on_deactivation()
	{
		if ( ! current_user_can( 'activate_plugins' ) )
			return;
		$plugin = isset( $_REQUEST['plugin'] ) ? $_REQUEST['plugin'] : '';
		check_admin_referer( "deactivate-plugin_{$plugin}" );

		// Uncomment this line to see the function in action
		// exit( var_dump( $_GET ) );
	}

	public static function on_uninstall()
	{
		if ( ! current_user_can( 'activate_plugins' ) )
			return;
		check_admin_referer( 'bulk-plugins' );

		// Important: check if this is the file that
		// was registered at the time the plugin was removed.
		if ( __FILE__ != WP_UNINSTALL_PLUGIN )
			return;

		// Uncomment this line to see the function in action
		// exit( var_dump( $_GET ) );
	}

	public function __construct()
	{
		// Run the plugin: add hooks to the desired functions
	}
}

#4 Using a namespace

If you are using a namespace in the main plugin file

namespace MYNAMESAPCE;

You will need to use the __NAMESPACE__ keyword in your code for register_deactivation_hook().

register_deactivation_hook( __FILE__ , __NAMESPACE__ . '\deactivate_plugin' );

Otherwise, the code will be unable to find the function deactivate_plugin() and will produce a warning:

PHP Warning: call_user_func_array() expects parameter 1 to be a valid callback, function ‘deactivate_plugin’ not found.

Changelog

Since 2.0.0

Introduced.

`register_deactivation_hook() register deactivation hook` code ^{WP 6.9.1}

wp-includes/plugin.php

function register_deactivation_hook( $file, $callback ) {
	$file = plugin_basename( $file );
	add_action( 'deactivate_' . $file, $callback );
}