Plugin uninstall function is not working

Question

I am updating my plugin for Wordpress version 3.5 compatibility. These are my important plugin files:

Sort_SearchResult_by_Title.php:

<?php
if(!class_exists('Class_Sortsearchresults'))
{
require_once('Class_Sortsearchresults.php');
}
if(!isset($Class_Sortsearchresults))
{
$Class_Sortsearchresults = new Class_Sortsearchresults;
}
?>

Class_Sortsearchresults.php:

<?php
class Class_Sortsearchresults
{
function __construct()
{

    //Register activation hook
       register_activation_hook(__FILE__,array(&$this,'sortresult_install'));

    //Add menu hook
    add_action( 'admin_menu', array(&$this,'sort_searchresults_menu'));

    //Update function hook
    add_action('plugins_loaded', array(&$this,'sortsearchtitle_update_db_check'));

    //Register deactivation hook
    register_deactivation_hook(__FILE__, array(&$this,'sortresult_uninstall'));

    //Run the search function
    add_action('pre_get_posts',array(&$this,'sort_searchresult_by_title'));

}

function sortresult_uninstall() 
{

    //This function is not working or executed

    global $wpdb;       
    $sortsearchtitle_db_version = '1.0';
    $table = $wpdb->prefix."sortsearchresult";
    $wpdb->query("DROP TABLE IF EXISTS $table");
    delete_option('sortsearchtitle_db_version');
}

function sortresult_install()
{
    //install function
}   

function sort_searchresults_menu()
{

    //function for creating menu

}

function sortsearchtitle_update_db_check()
{

    //function for update

    }

function settings_page()
{
    //function for settings form
}

function sortingguide($opt_val)
{

    //sorting options

}

function sort_searchresult_by_title($k)
{
    //function to run customized search

}

}
?>

It appears I have everything working well except the uninstall function. Any clues why this is not working? Thanks.

Answer 1

register_deactivation_hook() is launched when a plugin is deactivated. For plugin uninstall, there is register_uninstall_hook().

Wordpress plugins can also have a file called uninstall.php that is ran whenever the plugin is uninstalled. To prevent the uninstall.php file from being triggered directly, the state of a constant called WP_UNINSTALL_PLUGIN should be checked before launching the codes for uninstall.

Your uninstall.php could be:

<?php
//if uninstall not called from WordPress exit
if ( !defined( 'WP_UNINSTALL_PLUGIN' ) )
    exit ();

global $wpdb;       
$sortsearchtitle_db_version = '1.0';
$table = $wpdb->prefix."sortsearchresult";
$wpdb->query("DROP TABLE IF EXISTS $table");
delete_option('sortsearchtitle_db_version');