已激活的插件不会再次尝试激活。
它的工作方式是在尝试包含插件文件之前将重定向设置为错误。如果插件失败，则重定向不会被成功消息覆盖。此外，不会更新选项，也不会在插件错误时调用激活钩子。
应该注意的是，下面的代码实际上决不会阻止文件中的错误。代码不应该在别处用于复制使用重定向工作的“sandbox”。
如果发现任何错误或输出文本，那么它将被用来确保成功重定向将更新错误重定向。
$plugin
(string) (必需) 插件文件相对于plugins目录的路径。
$redirect
(string) (可选) 要重定向到的URL。
默认值： ''
$network_wide
(bool) (可选) 是否为网络中的所有站点或仅当前站点启用插件。仅限多站点。
默认值：false
$silent
(bool) (可选) 是否阻止调用激活钩子。
默认值：false
(WP_Error|null)在无效的文件上WP_Error或者成功时为null。
文件：wp-admin / includes / plugin.php
function activate_plugin( $plugin, $redirect = '', $network_wide = false, $silent = false ) {
$plugin = plugin_basename( trim( $plugin ) );
if ( is_multisite() && ( $network_wide || is_network_only_plugin( $plugin ) ) ) {
$network_wide = true;
$current = get_site_option( 'active_sitewide_plugins', array() );
$_GET['networkwide'] = 1; // Back compat for plugins looking for this value.
} else {
$current = get_option( 'active_plugins', array() );
}
$valid = validate_plugin( $plugin );
if ( is_wp_error( $valid ) ) {
return $valid;
}
if ( ( $network_wide && ! isset( $current[ $plugin ] ) ) || ( ! $network_wide && ! in_array( $plugin, $current ) ) ) {
if ( ! empty( $redirect ) ) {
wp_redirect( add_query_arg( '_error_nonce', wp_create_nonce( 'plugin-activation-error_' . $plugin ), $redirect ) ); // we'll override this later if the plugin can be included without fatal error
}
ob_start();
wp_register_plugin_realpath( WP_PLUGIN_DIR . '/' . $plugin );
$_wp_plugin_file = $plugin;
include_once( WP_PLUGIN_DIR . '/' . $plugin );
$plugin = $_wp_plugin_file; // Avoid stomping of the $plugin variable in a plugin.
if ( ! $silent ) {
/**
* Fires before a plugin is activated.
*
* If a plugin is silently activated (such as during an update),
* this hook does not fire.
*
* @since 2.9.0
*
* @param string $plugin Path to the plugin file relative to the plugins directory.
* @param bool $network_wide Whether to enable the plugin for all sites in the network
* or just the current site. Multisite only. Default is false.
*/
do_action( 'activate_plugin', $plugin, $network_wide );
/**
* Fires as a specific plugin is being activated.
*
* This hook is the "activation" hook used internally by register_activation_hook().
* The dynamic portion of the hook name, `$plugin`, refers to the plugin basename.
*
* If a plugin is silently activated (such as during an update), this hook does not fire.
*
* @since 2.0.0
*
* @param bool $network_wide Whether to enable the plugin for all sites in the network
* or just the current site. Multisite only. Default is false.
*/
do_action( "activate_{$plugin}", $network_wide );
}
if ( $network_wide ) {
$current = get_site_option( 'active_sitewide_plugins', array() );
$current[ $plugin ] = time();
update_site_option( 'active_sitewide_plugins', $current );
} else {
$current = get_option( 'active_plugins', array() );
$current[] = $plugin;
sort( $current );
update_option( 'active_plugins', $current );
}
if ( ! $silent ) {
/**
* Fires after a plugin has been activated.
*
* If a plugin is silently activated (such as during an update),
* this hook does not fire.
*
* @since 2.9.0
*
* @param string $plugin Path to the plugin file relative to the plugins directory.
* @param bool $network_wide Whether to enable the plugin for all sites in the network
* or just the current site. Multisite only. Default is false.
*/
do_action( 'activated_plugin', $plugin, $network_wide );
}
if ( ob_get_length() > 0 ) {
$output = ob_get_clean();
return new WP_Error( 'unexpected_output', __( 'The plugin generated unexpected output.' ), $output );
}
ob_end_clean();
}
return null;
}基本例子
尝试激活插件，并在失败时返回WP_Error
插件缓存问题
在插件全部初始化之后，添加或修改插件文件时会导致插件缓存出现问题。这可以通过重新加载页面，将activate_plugin()作为单独的AJAX请求发送，或者如果需要，通过手动更新缓存来解决。以下示例;
$cache_plugins = wp_cache_get( 'plugins', 'plugins' );
if ( !empty( $cache_plugins ) ) {
$new_plugin = array(
'Name' => $plugin_name,
'PluginURI' => $plugin_uri,
'Version' => $plugin_version,
'Description' => $plugin_description,
'Author' => $author_name,
'AuthorURI' => $author_uri,
'TextDomain' => '',
'DomainPath' => '',
'Network' => '',
'Title' => $plugin_name,
'AuthorName' => $author_name,
);
$cache_plugins[''][$plugin_path] = $new_plugin;
wp_cache_set( 'plugins', $cache_plugins, 'plugins' );
}
