I've written a plugin that allows users to bookmark their favorite posts, but have run into a small problem when using it on a multisite network.

Each time a post is bookmarked, the ID of that post is stored in an array of IDs in the current user's meta table. This all works great, until it's used on a MS setup.

If viewing the site that the bookmarks were created on, everything works great, but when viewing a different site, I get a list of post IDs that belong to the other site. This is because the user meta table is shared between sites.

So, what I need to do is retrieve only the user meta for the current site. Is there a way to do this? I don't think there is, so if anyone has some insight, that'd be great.

2 Answers 2


WordPress distinguishes usermeta keys between sites by using the database prefix for each site.

For example, instead of using the favorite_posts key, you'd use the meta key wp_23_favorite_posts. To get the prefix, you can use $wpdb->get_blog_prefix().

But wait, there's actually a whole API dedicated to this. Rather than using *_user_meta(), use *_user_option(). These are internally translated to be against the individual site.

And, it's easily integrated into your existing plugin. get_user_option() checks against a site-specific key first, but if it doesn't find anything, it falls back to a user-wide meta key. So go ahead and switch to get_user_option() and your existing plugin will work on single site without a problem.

Here are the function definitions:

./wp-includes/user.php:251:function get_user_option( $option, $user = 0 )
./wp-includes/user.php:293:function update_user_option( $user_id, $option_name, $new_value )
./wp-includes/user.php:322:function delete_user_option( $user_id, $option_name )
  • Oh, cool! I didn't know about get_user_option(). I will test it and let you know.
    – Pippin
    Commented Nov 16, 2011 at 15:58
  • what is interesting is that if I want to delete a site wide piece of user meta I must use delete_user_meta() because if I use delete_user_option() it prefixes the option with 'wp_' - which I'm guessing is the default site prefix.
    – jester66
    Commented Oct 29, 2013 at 15:33
  • Seems this person wants only the user meta for a specific site. How is using get_user_option supposed to help when it falls back to a user-wide meta key? user-wide here soulds like the full network. But don't want the network, just a site. Don't want the fallback here. So this seems like it does not help any. Commented Sep 19, 2017 at 19:13

why not store the blog id together with the array of postIds, so you will have something like this stored in the user meta data:

   [blogid1] => Array(1,2,4,7),
   [blogid2] => Array(3,6,8,10)

you can use the global $blog_id to get the current blogid. On a non multisite setup, the blogid will be 0 and should still work when you try to get the posts out the array by


  • This is what I've been considering doing. The only issue I have with it is that it won't work with users who have already been using the plugin, though I suppose I could just write an upgrade function that would move all of the currently stored bookmarks into the new array structure.
    – Pippin
    Commented Nov 14, 2011 at 14:44

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