我有一个类，它有一个在数据库中检查和创建表的函数。为此，我需要使用WordPress$wpdb对象。
我需要该函数仅在第一次插件激活时运行，所以我使用该功能：
register_activation_hook ( __FILE__, array( 'MemorialCandles', 'dbInstall' ) );
问题是我总是收到此错误：
致命错误：不在对象上下文中使用$this 在/home/xxx/xxx/wordpress/wp-content/plugins/MemorialCandles/memorial-candles.class.php第 77 行
类代码：
<?php
// Global Variables:
global $wpdb;
register_activation_hook ( __FILE__, array( 'MemorialCandles', 'dbInstall' ) );
/**
* Class: MemorialCandles
*
* Provides skeleton to the plugin and handles queries and action.
*
* @author Dor Zuberi <dor@zubri.me>
* @copyright 2011 Dor Zuberi
* @license http://www.php.net/license/3_01.txt
*/
class MemorialCandles
{
// Variables
/**
* @var string stores plugin direction - RTL or LTR.
*/
private $pluginDirection;
/**
* @var string stores the plugin database table name.
*/
private $tableName;
// Constructor
/**
* Initiates the plugin, stores and configure the basic setup procedures.
*
* @return void
*/
function __construct()
{
global $wpdb;
$this->tableName = $wpdb->prefix . 'memorialcandles';
}
// Getters
// Setters
// Methods
/**
* Handles the database table creation.
*
* @return void
*/
function dbInstall()
{
global $wpdb;
if( $wpdb->get_var( "SHOW TABLES LIKE `{$this->tableName}`" ) != $this->tableName )
{
$sql = "CREATE TABLE `{$this->tableName}` (
id int(8) NOT NULL AUTO_INCREMENT,
fullName text NOT NULL,
message text NOT NULL,
postDate text NOT NULL,
galleryID int(8) NOT NULL,
UNIQUE KEY id(id)
);";
require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );
dbDelta( $sql );
}
}
/**
* Handles the database table drop procedure.
*
* @return void
*/
function dbUninstall()
{
global $wpdb;
$sql = "DROP TABLE IF EXISTS `{$this->tableName}`;";
$wpdb->query( $sql );
}
}
?>
提前感谢！ :D
要在回调中使用实例方法，回调需要一个实例。您需要为调用 register_activation_hook 创建一个实例：
register_activation_hook(__FILE__, array(new MemorialCandles(), 'dbInstall'));
或dbInstall类方法。
class MemorialCandles {
// Variables
/**
* @var string stores the plugin database table name.
*/
private static $tableName, $tableSuffix = 'memorialcandles';
...
// Methods
/**
* Handles the database table creation.
*
* @return void
*/
static function dbInstall() {
global $wpdb;
$tableName = self::$tableName = $wpdb->prefix . self::$tableSuffix;
if( $wpdb->get_var( "SHOW TABLES LIKE `{$tableName}`" ) != $tableName )
{
$sql = "CREATE TABLE `{$tableName}` (
id int(8) UNSIGNED NOT NULL AUTO_INCREMENT,
fullName text NOT NULL,
message text NOT NULL,
postDate text NOT NULL,
galleryID int(8) UNSIGNED NOT NULL,
UNIQUE KEY id(id)
);";
require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );
dbDelta( $sql );
}
}
...
}