Gets/stores a transient set to an array of blog option meta for sites across a multisite network.

Get&Set Multisite Blog Option Transients.md

Network-wide queries are very costly, performance-wise. If you need to get or display lists of per-blog meta values network-wide, it's better to save it as a transient so that the query doesn't bog down the site.

####To Do:

• remove $time parameter, and just set the expiry far in the future
• call delete_site_transient whenever a site is added or has its status changed, or when a site modifies the specified meta

gistfile1.php

<?php

function multisite_option_transients( $option, $time ) {

  // Get transient if it exists
  $transient = get_site_transient($option);

  // If transient isn't set, get data then set transient
  if ( empty($transient) ) {
    global $wpdb;

    // Get an array of blog ids (omits sites deleted or flagged as spam, archived, mature)
    $sites = $wpdb->get_col( $wpdb->prepare(
      "SELECT blog_id FROM $wpdb->blogs 
       WHERE archived = %s
       AND mature = '0' 
       AND spam = '0' 
       AND deleted = '0'", '0'  ) ); // new prepare function requires two parameters

    // Create an array of site options
    if ( is_array($sites) ) {
      $transient = array();

      // Loop through the site IDs and get option for each
      foreach ($sites as $site) {
        $name = get_blog_details( $site )->blogname;
        $site_option = get_blog_option( $site, $option );
        $transient[$site] = array( 'name' => $name, $option => $site_option );
      }
    }

    // Store site options array to transient
    set_site_transient( $option, $transient, $time );
  }

  // Return transient data
  return $transient;

}