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@hakre
Created November 23, 2010 14:56
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Wordpress Block Category Delete Example
<?php
/**
* Block deletion of certain categories by their ID.
*
* Copyright (C) 2010 hakre <http://hakre.wordpress.com/>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* USAGE:
*
* Pass IDs of categories to block as array to ::bootstrap();
*
* @author hakre <http://hakre.wordpress.com>
* @see http://wordpress.stackexchange.com/questions/4439/can-i-prevent-wp-users-even-admin-from-deleting-custom-categories
*/
return blockCategoriesDeletionPlugin::bootstrap(array(33, 34, 35)); // pass IDs of categories to block as array
class blockCategoriesDeletionPlugin {
/**
* @var blockCategoriesDeletionPlugin
*/
static $instance;
private $categoryIDs = array();
public static function bootstrap(array $categoryIDs) {
if (null===self::$instance) {
self::$instance = new self($categoryIDs);
} else {
throw new BadFunctionCallException(sprintf('Plugin %s already instantiated', __CLASS__));
}
return self::$instance;
}
private function isCategoryDeleteRequest() {
$notAnCategoryDeleteRequest =
empty($_REQUEST['taxonomy'])
|| empty($_REQUEST['action'])
|| $_REQUEST['taxonomy'] !== 'category'
|| !( $_REQUEST['action'] === 'delete' || $_REQUEST['action'] === 'delete-tag');
$isCategoryDeleteRequest = !$notAnCategoryDeleteRequest;
return $isCategoryDeleteRequest;
}
public function __construct(array $categoryIDs) {
$this->categoryIDs = $categoryIDs;
if ($this->isCategoryDeleteRequest()) {
add_filter('check_admin_referer', array($this, 'check_referrer'), 10, 2);
add_filter('check_ajax_referer', array($this, 'check_referrer'), 10, 2);
}
}
private function blockCategoryID($categoryID) {
return in_array($categoryID, $this->categoryIDs);
}
/**
* @-wp-hook check_admin_referer
* @-wp-hook check_ajax_referer
*/
public function check_referrer($action, $result) {
if (!$this->isCategoryDeleteRequest()) {
return;
}
$prefix = 'delete-tag_';
if (strpos($action, $prefix) !== 0)
return;
$actionID = substr($action, strlen($prefix));
$categoryID = max(0, (int) $actionID);
if ($this->blockCategoryID($categoryID)) {
wp_die(__('This category is blocked for deletion.'));
}
}
}
#EOF;
@jemoreto
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Thanks for this! Works like a charm.

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