Uninstall, Activate, Deactivate a plugin: typical features & how-to

#1 楼

有三个不同的钩子。它们在以下情况下触发：


卸载
停用
激活

如何在方案中安全触发功能

以下显示了正确挂接在上述操作期间触发的回调函数的正确方法。

您可以在使用


普通函数，
一个类或
外部类，

我将展示三个不同的演示插件，您可以检查它们，然后在以后实现代码在您自己的插件中。

重要的事前通知！

由于该主题非常困难且非常详细，并且具有十几种极端情况，因此此答案永远不会是完美的。我会随着时间的推移不断改进它，因此请定期检查。

（1）激活/停用/卸载插件。

插件设置回调由触发核心，您对核心的执行方式没有任何影响。有一些事情要记住：



在设置回调期间，永远不要echo/print any（！）。这将导致headers already sent消息，核心将建议停用并删除您的插件...不要问：我知道...
您将看不到任何可视输出。但是我在所有不同的回调中添加了exit()语句，因此您可以对实际发生的情况有一些了解。只需取消注释即可看到工作正常。
检查__FILE__ != WP_PLUGIN_INSTALL和（如果不是：中止！）是否真的在卸载插件非常重要。我建议在开发过程中简单地触发on_deactivation()回调，这样可以节省您将所有内容恢复原状的时间。至少这是我要做的。
我还做一些安全性工作。有些也是由核心完成的，但是，嘿！安全胜过遗憾！。

首先，我没有在未加载核心的情况下禁止直接文件访问：defined( 'ABSPATH' ) OR exit;

然后我检查是否允许当前用户执行此任务。
作为最后一项任务，我检查引荐来源。注意：如果出现错误，wp_die()屏幕可能会出现意外的结果，要求您提供适当的权限（并且是否要重试...是的，当然）。发生这种情况是因为核心将您重定向，将当前$GLOBALS['wp_list_table']->current_action();设置为error_scrape，然后检查check_admin_referer('plugin-activation-error_' . $plugin);的引荐来源网址，其中$plugin是$_REQUEST['plugin']。因此，重定向发生在页面加载量的一半时，您将获得此有线滚动条，并且die屏幕会看到黄色的管理员通知/消息框。如果发生这种情况：请保持冷静，并通过一些exit()和逐步调试来查找错误。



（A）纯函数插件

请记住，如果在函数定义之前挂接了回调，这可能无法正常工作。

<?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
 */

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 the following 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 the following 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 the file is the one
    // that was registered during the uninstall hook.
    if ( __FILE__ != WP_UNINSTALL_PLUGIN )
        return;

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

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' );

（B）基于类/ OOP的体系结构

这是当今插件中最常见的示例。

<?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 the following 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 the following 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 the file is the one
        // that was registered during the uninstall hook.
        if ( __FILE__ != WP_UNINSTALL_PLUGIN )
            return;

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

    public function __construct()
    {
        # INIT the plugin: Hook your callbacks
    }
}

（C）具有外部设置对象的基于类/ OOP架构

此场景假设您在名为setup.php的插件的子目录：inc中获得了一个主插件文件和另一个名为~/wp-content/plugins/your_plugin/inc/setup.php的文件。当plugin文件夹不在默认WP文件夹结构之外时，以及在重命名目录dir或安装文件的名称不同的情况下，此方法也将起作用。在插件根目录中，只有inc文件夹必须具有相同的名称和位置。

注意：您可以简单地使用三个register_*_hook()*函数和类并将它们放入您的插件中。

主插件文件：

<?php
defined( 'ABSPATH' ) OR exit;
/**
 * Plugin Name: (WCM) Activate/Deactivate/Uninstall - FILE/CLASS
 * Description: Example Plugin
 * 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_File_Inc', 'on_activation' ) );
register_deactivation_hook( __FILE__, array( 'WCM_Setup_Demo_File_Inc', 'on_deactivation' ) );
register_uninstall_hook(    __FILE__, array( 'WCM_Setup_Demo_File_Inc', 'on_uninstall' ) );

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

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

    public function __construct()
    {
        add_action( current_filter(), array( $this, 'load_files' ), 30 );
    }

    public function load_files()
    {
        foreach ( glob( plugin_dir_path( __FILE__ ).'inc/*.php' ) as $file )
            include_once $file;
    }
}

设置文件：

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

class WCM_Setup_Demo_File_Inc
{
    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 the following 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 the following 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 the file is the one
        // that was registered during the uninstall hook.
        if ( __FILE__ != WP_UNINSTALL_PLUGIN )
            return;

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

（2 ）插件更新

如果编写的插件具有自己的数据库表或选项，则可能需要更改或升级内容。

遗憾的是，到目前为止，无法在插件/主题安装或更新/升级上运行某些东西。很高兴有一种解决方法：将自定义函数挂接到自定义选项（是的，虽然很la脚-但却可以使用）。

function prefix_upgrade_plugin() 
{
    $v = 'plugin_db_version';
    $update_option = null;
    // Upgrade to version 2
    if ( 2 !== get_option( $v ) ) 
    {
        if ( 2 < get_option( $v ) )
        {
            // Callback function must return true on success
            $update_option = custom_upgrade_cb_fn_v3();

            // Only update option if it was an success
            if ( $update_option )
                update_option( $v, 2 );
        }
    }

    // Upgrade to version 3, runs just after upgrade to version 2
    if ( 3 !== get_option( $v ) ) 
    {
        // re-run from beginning if previous update failed
        if ( 2 < get_option( $v ) )
            return prefix_upgrade_plugin();

        if ( 3 < get_option( $v ) )
        {
            // Callback function must return true on success
            $update_option = custom_upgrade_cb_fn_v3();

            // Only update option if it was an success
            if ( $update_option )
                update_option( $v, 3 );
        }
    }

    // Return the result from the update cb fn, so we can test for success/fail/error
    if ( $update_option )
        return $update_option;

return false;
}
add_action('admin_init', 'prefix_upgrade_plugin' );

源

这个更新功能不是一个很好/写得很好的例子，但是如前所述：这是一个例子，该技术效果很好。将在以后的更新中对此进行改进。

#2 楼

要测试当前系统是否具有所需的功能（例如PHP版本或已安装的扩展），可以使用以下代码：

<?php  # -*- coding: utf-8 -*-
/**
 * Plugin Name: T5 Check Plugin Requirements
 * Description: Test for PHP version and installed extensions
 * Plugin URI:
 * Version:     2013.03.31
 * Author:      Thomas Scholz
 * Author URI:  http://toscho.de
 * Licence:     MIT
 * License URI: http://opensource.org/licenses/MIT
 */

/*
 * Don't start on every page, the plugin page is enough.
 */
if ( ! empty ( $GLOBALS['pagenow'] ) && 'plugins.php' === $GLOBALS['pagenow'] )
    add_action( 'admin_notices', 't5_check_admin_notices', 0 );

/**
 * Test current system for the features the plugin needs.
 *
 * @return array Errors or empty array
 */
function t5_check_plugin_requirements()
{
    $php_min_version = '5.4';
    // see http://www.php.net/manual/en/extensions.alphabetical.php
    $extensions = array (
        'iconv',
        'mbstring',
        'id3'
    );
    $errors = array ();

    $php_current_version = phpversion();

    if ( version_compare( $php_min_version, $php_current_version, '>' ) )
        $errors[] = "Your server is running PHP version $php_current_version but
            this plugin requires at least PHP $php_min_version. Please run an upgrade.";

    foreach ( $extensions as $extension )
        if ( ! extension_loaded( $extension ) )
            $errors[] = "Please install the extension $extension to run this plugin.";

    return $errors;

}

/**
 * Call t5_check_plugin_requirements() and deactivate this plugin if there are error.
 *
 * @wp-hook admin_notices
 * @return  void
 */
function t5_check_admin_notices()
{
    $errors = t5_check_plugin_requirements();

    if ( empty ( $errors ) )
        return;

    // Suppress "Plugin activated" notice.
    unset( $_GET['activate'] );

    // this plugin's name
    $name = get_file_data( __FILE__, array ( 'Plugin Name' ), 'plugin' );

    printf(
        '<div class="error"><p>%1$s</p>
        <p><i>%2$s</i> has been deactivated.</p></div>',
        join( '</p><p>', $errors ),
        $name[0]
    );
    deactivate_plugins( plugin_basename( __FILE__ ) );
}

使用PHP 5.5进行测试：