restore_current_blog()

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概述

restore_current_blog() 函数用于在调用 switch_to_blog() 后恢复当前博客，确保全局变量状态正确。它返回布尔值表示操作成功与否，并处理数据库和缓存切换。

关键要点

必须在每次 switch_to_blog() 后调用 restore_current_blog()，否则 $GLOBALS['_wp_switched_stack'] 可能非空，导致 WP 错误判断切换状态，影响如 wp_upload_dir() 的 URL 返回。
函数返回 true 表示成功恢复，false 表示已在当前博客（即 $GLOBALS['_wp_switched_stack'] 为空）。
内部机制包括：检查切换栈、设置数据库 ID、更新全局变量、处理缓存切换（通过 wp_cache_switch_to_blog() 或手动初始化），并触发 switch_blog 钩子。
建议优先使用 restore_current_blog() 而非手动清空 $GLOBALS['_wp_switched_stack']，以避免 hack 方式。

代码示例

switch_to_blog( 5 );

/* Do stuff */

restore_current_blog();

📄 原文内容

Restores the current blog, after calling switch_to_blog() .

Return

bool True on success, false if we’re already on the current blog.

restore_current_blog() should be called after every switch_to_blog(). If not, a global variable which monitors the switching, $GLOBALS['_wp_switched_stack'], will not be empty even if you use switch_to_blog() to return to the original blog. If $GLOBALS['_wp_switched_stack'] is not empty, WP will think it is in a switched state and can potentially return the wrong URL for the site via wp_upload_dir(). See http://wordpress.stackexchange.com/a/123516/27757

When calling switch_to_blog() repeatedly, either call restore_current_blog() each time, or save the original blog ID until the end and call switch_to_blog() with that and do:

$GLOBALS['_wp_switched_stack'] = array();<br> $GLOBALS['switched'] = false;

The former is probably preferable, as it is not a hack.

Source

function restore_current_blog() {
	global $wpdb;

	if ( empty( $GLOBALS['_wp_switched_stack'] ) ) {
		return false;
	}

	$new_blog_id  = array_pop( $GLOBALS['_wp_switched_stack'] );
	$prev_blog_id = get_current_blog_id();

	if ( $new_blog_id === $prev_blog_id ) {
		/** This filter is documented in wp-includes/ms-blogs.php */
		do_action( 'switch_blog', $new_blog_id, $prev_blog_id, 'restore' );

		// If we still have items in the switched stack, consider ourselves still 'switched'.
		$GLOBALS['switched'] = ! empty( $GLOBALS['_wp_switched_stack'] );

		return true;
	}

	$wpdb->set_blog_id( $new_blog_id );
	$GLOBALS['blog_id']      = $new_blog_id;
	$GLOBALS['table_prefix'] = $wpdb->get_blog_prefix();

	if ( function_exists( 'wp_cache_switch_to_blog' ) ) {
		wp_cache_switch_to_blog( $new_blog_id );
	} else {
		global $wp_object_cache;

		if ( is_object( $wp_object_cache ) && isset( $wp_object_cache->global_groups ) ) {
			$global_groups = $wp_object_cache->global_groups;
		} else {
			$global_groups = false;
		}

		wp_cache_init();

		if ( function_exists( 'wp_cache_add_global_groups' ) ) {
			if ( is_array( $global_groups ) ) {
				wp_cache_add_global_groups( $global_groups );
			} else {
				wp_cache_add_global_groups(
					array(
						'blog-details',
						'blog-id-cache',
						'blog-lookup',
						'blog_meta',
						'global-posts',
						'image_editor',
						'networks',
						'network-queries',
						'sites',
						'site-details',
						'site-options',
						'site-queries',
						'site-transient',
						'theme_files',
						'rss',
						'users',
						'user-queries',
						'user_meta',
						'useremail',
						'userlogins',
						'userslugs',
					)
				);
			}

			wp_cache_add_non_persistent_groups( array( 'counts', 'plugins', 'theme_json' ) );
		}
	}

	/** This filter is documented in wp-includes/ms-blogs.php */
	do_action( 'switch_blog', $new_blog_id, $prev_blog_id, 'restore' );

	// If we still have items in the switched stack, consider ourselves still 'switched'.
	$GLOBALS['switched'] = ! empty( $GLOBALS['_wp_switched_stack'] );

	return true;
}

View all references View on Trac View on GitHub

Hooks

do_action( ‘switch_blog’, int $new_blog_id, int $prev_blog_id, string $context ): Fires when the blog is switched.

Uses	Description
wp_cache_switch_to_blog()`wp-includes/cache.php`	Switches the internal blog ID.
wp_cache_init()`wp-includes/cache.php`	Sets up Object Cache Global and assigns it.
wp_cache_add_global_groups()`wp-includes/cache.php`	Adds a group or set of groups to the list of global groups.
wp_cache_add_non_persistent_groups()`wp-includes/cache.php`	Adds a group or set of groups to the list of non-persistent groups.
wpdb::set_blog_id()`wp-includes/class-wpdb.php`	Sets blog ID.
wpdb::get_blog_prefix()`wp-includes/class-wpdb.php`	Gets blog prefix.
get_current_blog_id()`wp-includes/load.php`	Retrieves the current site ID.
do_action()`wp-includes/plugin.php`	Calls the callback functions that have been added to an action hook.

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Used by	Description
WP_User_Query::get_cache_last_changed()`wp-includes/class-wp-user-query.php`	Retrieves the last changed cache timestamp for users and optionally posts.
user_can_for_site()`wp-includes/capabilities.php`	Returns whether a particular user has the specified capability for a given site.
current_user_can_for_site()`wp-includes/capabilities.php`	Returns whether the current user has the specified capability for a given site.
wp_initialize_site()`wp-includes/ms-site.php`	Runs the initialization routine for a given site.
wp_uninitialize_site()`wp-includes/ms-site.php`	Runs the uninitialization routine for a given site.
wp_is_site_initialized()`wp-includes/ms-site.php`	Checks whether a site is initialized.
get_oembed_response_data_for_url()`wp-includes/embed.php`	Retrieves the oEmbed response data for a given URL.
WP_Site::get_details()`wp-includes/class-wp-site.php`	Retrieves the details for this site.
has_custom_logo()`wp-includes/general-template.php`	Determines whether the site has a custom logo.
get_custom_logo()`wp-includes/general-template.php`	Returns a custom logo, linked to home unless the theme supports removing the link on the home page.
wp_get_users_with_no_role()`wp-includes/user.php`	Gets the user IDs of all users with no role on this site.
get_site_icon_url()`wp-includes/general-template.php`	Returns the Site Icon URL.
WP_MS_Sites_List_Table::column_blogname()`wp-admin/includes/class-wp-ms-sites-list-table.php`	Handles the site name column output.
confirm_another_blog_signup()`wp-signup.php`	Shows a message confirming that the new site has been created.
wpmu_delete_user()`wp-admin/includes/ms.php`	Deletes a user and all of their posts from the network.
upload_space_setting()`wp-admin/includes/ms.php`	Displays the site upload space quota setting form on the Edit Site Settings screen.
wpmu_delete_blog()`wp-admin/includes/ms.php`	Deletes a site.
WP_Users_List_Table::get_views()`wp-admin/includes/class-wp-users-list-table.php`	Returns an associative array listing all the views that can be used with this table.
WP_User::get_role_caps()`wp-includes/class-wp-user.php`	Retrieves all of the capabilities of the user’s roles, and merges them with individual user capabilities.
WP_Theme::get_allowed_on_site()`wp-includes/class-wp-theme.php`	Returns array of stylesheet names of themes allowed on the site.
get_home_url()`wp-includes/link-template.php`	Retrieves the URL for a given site where the front end is accessible.
get_site_url()`wp-includes/link-template.php`	Retrieves the URL for a given site where WordPress application files (e.g. wp-blog-header.php or the wp-admin/ folder) are accessible.
wp_admin_bar_my_sites_menu()`wp-includes/admin-bar.php`	Adds the “My Sites/[Site Name]” menu and all submenus.
count_users()`wp-includes/user.php`	Counts number of users who have each of the user roles.
newblog_notify_siteadmin()`wp-includes/ms-functions.php`	Notifies the network admin that a new site has been activated.
get_blog_post()`wp-includes/ms-functions.php`	Gets a blog post from any site on the network.
add_user_to_blog()`wp-includes/ms-functions.php`	Adds a user to a blog, along with specifying the user’s role.
remove_user_from_blog()`wp-includes/ms-functions.php`	Removes a user from a blog.
get_blog_permalink()`wp-includes/ms-functions.php`	Gets the permalink for a post on another blog.
create_empty_blog()`wp-includes/ms-deprecated.php`	Create an empty blog.
get_blog_option()`wp-includes/ms-blogs.php`	Retrieves option value for a given blog id based on name of option.
add_blog_option()`wp-includes/ms-blogs.php`	Adds a new option for a given blog ID.
delete_blog_option()`wp-includes/ms-blogs.php`	Removes an option by name for a given blog ID. Prevents removal of protected WordPress options.
update_blog_option()`wp-includes/ms-blogs.php`	Updates an option for a particular blog.
get_blog_details()`wp-includes/ms-blogs.php`	Retrieves the details for a blog from the blogs table and blog options.
wp_xmlrpc_server::wp_getUsersBlogs()`wp-includes/class-wp-xmlrpc-server.php`	Retrieves the blogs of the user.

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Changelog

Version	Description
MU (3.0.0)	Introduced.

User Contributed Notes

Skip to note 2 content

Codex

10 years ago

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```
switch_to_blog( 5 );

/* Do stuff */

restore_current_blog();
```
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