Adds a user to a blog, along with specifying the user’s role.

Description

Use the ‘add_user_to_blog’ action to fire an event when users are added to a blog.

Parameters

$blog_idintrequired

ID of the blog the user is being added to.

$user_idintrequired

ID of the user being added.

$rolestringrequired

User role.

Return

More Information

• It does not check if the user is already a member of the blog before setting their role. If you don’t want to overwrite the role of a user if they are already a member of the blog, use is_user_member_of_blog() to check that first.
• You do not need to call switch_to_blog() to switch to the blog you want to add the user to before calling this function. The function will switch to the blog itself, and restore the current blog before returning as well.

Source

function add_user_to_blog( $blog_id, $user_id, $role ) {
	switch_to_blog( $blog_id );

	$user = get_userdata( $user_id );

	if ( ! $user ) {
		restore_current_blog();
		return new WP_Error( 'user_does_not_exist', __( 'The requested user does not exist.' ) );
	}

	/**
	 * Filters whether a user should be added to a site.
	 *
	 * @since 4.9.0
	 *
	 * @param true|WP_Error $retval  True if the user should be added to the site, error
	 *                               object otherwise.
	 * @param int           $user_id User ID.
	 * @param string        $role    User role.
	 * @param int           $blog_id Site ID.
	 */
	$can_add_user = apply_filters( 'can_add_user_to_blog', true, $user_id, $role, $blog_id );

	if ( true !== $can_add_user ) {
		restore_current_blog();

		if ( is_wp_error( $can_add_user ) ) {
			return $can_add_user;
		}

		return new WP_Error( 'user_cannot_be_added', __( 'User cannot be added to this site.' ) );
	}

	if ( ! get_user_meta( $user_id, 'primary_blog', true ) ) {
		update_user_meta( $user_id, 'primary_blog', $blog_id );
		$site = get_site( $blog_id );
		update_user_meta( $user_id, 'source_domain', $site->domain );
	}

	$user->set_role( $role );

	/**
	 * Fires immediately after a user is added to a site.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param int    $user_id User ID.
	 * @param string $role    User role.
	 * @param int    $blog_id Blog ID.
	 */
	do_action( 'add_user_to_blog', $user_id, $role, $blog_id );

	clean_user_cache( $user_id );
	wp_cache_delete( $blog_id . '_user_count', 'blog-details' );

	restore_current_blog();

	return true;
}

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Hooks

do_action( ‘add_user_to_blog’, int $user_id, string $role, int $blog_id )

Fires immediately after a user is added to a site.

apply_filters( ‘can_add_user_to_blog’, true|WP_Error $retval, int $user_id, string $role, int $blog_id )

Filters whether a user should be added to a site.

Changelog