switch_to_blog( int $new_blog_id, bool $deprecated = null )
Switch the current blog.
Contents
Description Description
This function is useful if you need to pull posts, or other information, from other blogs. You can switch back afterwards using restore_current_blog().
Things that aren’t switched:
- plugins. See #14941
See also See also
Parameters Parameters
- $new_blog_id
-
(int) (Required) The ID of the blog to switch to. Default: current blog.
- $deprecated
-
(bool) (Optional) Not used.
Default value: null
Return Return
(true) Always returns true.
Source Source
File: wp-includes/ms-blogs.php
function switch_to_blog( $new_blog_id, $deprecated = null ) {
global $wpdb;
$prev_blog_id = get_current_blog_id();
if ( empty( $new_blog_id ) ) {
$new_blog_id = $prev_blog_id;
}
$GLOBALS['_wp_switched_stack'][] = $prev_blog_id;
/*
* If we're switching to the same blog id that we're on,
* set the right vars, do the associated actions, but skip
* the extra unnecessary work
*/
if ( $new_blog_id == $prev_blog_id ) {
/**
* Fires when the blog is switched.
*
* @since MU (3.0.0)
*
* @param int $new_blog_id New blog ID.
* @param int $prev_blog_id Previous blog ID.
*/
do_action( 'switch_blog', $new_blog_id, $prev_blog_id );
$GLOBALS['switched'] = true;
return true;
}
$wpdb->set_blog_id( $new_blog_id );
$GLOBALS['table_prefix'] = $wpdb->get_blog_prefix();
$GLOBALS['blog_id'] = $new_blog_id;
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( 'users', 'userlogins', 'usermeta', 'user_meta', 'useremail', 'userslugs', 'site-transient', 'site-options', 'blog-lookup', 'blog-details', 'rss', 'global-posts', 'blog-id-cache', 'networks', 'sites', 'site-details', 'blog_meta' ) );
}
wp_cache_add_non_persistent_groups( array( 'counts', 'plugins' ) );
}
}
/** This filter is documented in wp-includes/ms-blogs.php */
do_action( 'switch_blog', $new_blog_id, $prev_blog_id );
$GLOBALS['switched'] = true;
return true;
}
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Changelog Changelog
| Version | Description |
|---|---|
| MU (3.0.0) | Introduced. |
User Contributed Notes User Contributed Notes
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One switch
Multiple switches
foreach( $blog_ids as $blog_id ){ switch_to_blog( $blog_id ); //Do stuff restore_current_blog(); }If you do not call restore_current_blog() after every switch_to_blog(), WordPress can get into a state that can potentially build the wrong urls for the site. See restore_current_blog() vs switch_to_blog().
Description
Restores previous blog after a switch_to_blog call.
Contrary to the function’s name, this does NOT restore the original blog but the previous blog. Calling `switch_to_blog()` twice in a row and then calling this function will result in being on the blog set by the first `switch_to_blog()` call.
I was a little confused with the
switch_to_blog()functionality when I first started using it. This function only affects the database which is being accessed on the network. I cannot access blocks of code, classes, functions, or variables that exist within a specific blog on the network. By extension, this also means that I cannot access themes or plugins that only exist on one site on the network. I was hoping for a little more power with this function before I realized that this was limited to site data being stored in the database.The following example does not work:
Site 1 --> Site1_only_plugin --> Site1_only_plugin_function()That is, Site 1 has a unique plugin that has a bit of functionality that I want to access on Site 2 (or anywhere else on the network) without loading the full plugin to Site 2. I might be tempted to do something like this from Site 2:
This does not work. I can only use the
switch_to_blog()functionality to access database values from other sites on the network. Here’s an example that does work:Site 1 --> Site1_only_plugin --> Site1_only_plugin_function()--> add_option( 'Site1_only_plugin_option', $var )The plugin on Site 1 has first set a value in the Site 1 database. I can then access that value in the options table from anywhere on the network as follows: