User meta in WordPress multisite

Have you ever needed to save user specific data in WordPress? Have you ever wondered how user specific settings work in multisite? Do you want settings to be global and shared across all sub sites? Or do you need to retrieve the user meta setting for the current site where the user meta setting can be different in all sub sites?

Luckily WordPress covers all these scenarios. Let’s start with *_user_meta() functions.

Global user meta

In user profile page we already have several WordPress core settings:

• Color Scheme
• First Name
• Last Name
• etc.

If you update First Name, the value is changed for all sub sites. That makes perfect sense, your name remains the same in all sub sites. I call that global user setting.

How to set global custom user meta

Sometimes we want to add our own settings in the user profile page. Custom user meta can be for example occupation, expire date in membership sites, or checkbox for approving the user.

There are four functions for adding, updating, retrieving or deleting custom user meta:

1. Add user meta
2. Update user meta
3. Get user meta
4. Delete user meta

In our example we add simple text where meta key is called multisite_user_meta_setting.

$user_id    = 1;
$meta_key   = 'multisite_user_meta_setting';
$meta_value = 'Sample text';
add_user_meta( $user_id, $meta_key, $meta_value );

Setting is saved in database table called wp_usermeta. Now we could update, get or delete meta value but that’s not focus in this tutorial. If we use the same code in multisite install everything stays the same. User meta value remains as global setting across all sub sites.

User meta in WordPress multisite

In previous chapter we used *_user_meta() functions but there are also *_user_option() functions:

• Update user option
• Get user option
• Delete user option

These functions checks against a site-specific meta key first, but if it doesn’t find anything, it falls back to a user-wide meta key. It means that same user can have different meta values for the same setting in multisite. For example we can have membership site in multisite install and expire date can be different in all sub sites when using *_user_option() functions.

How does user meta works in multisite

We can use the same example as before but instead of using add_user_meta() we use update_user_option() function.

$user_id     = 1;
$option_name = 'multisite_user_meta_setting';
$new_value   = 'Sample text';
update_user_option( $user_id, $option_name, $new_value );

update_user_option function prepend the WordPress table prefix to the option name automatically. This is what happens behind the scenes.

• Let’s say our table prefix is sk_
• Main site of multisite (and in single installs) meta key looks like this: sk_multisite_user_meta_setting
• In sub site there is also blog ID in the prefix. Meta key in sub site (where ID is 7) looks like this: sk_7_multisite_user_meta_setting

Now you can retrieve different meta values automatically and WordPress takes care of prefixing:

// Get setting
$setting = get_user_option( 'multisite_user_meta_setting', $user_id );

WordPress checks the prefix in sub site where blog ID is seven (7) in this order:

1. sk_7_multisite_user_meta_setting
2. sk_multisite_user_meta_setting
3. multisite_user_meta_setting

So it even works when you switch from *_user_meta() to *_user_option() functions because WordPress automatically falls back for non prefixed meta key. How cool is that!

Examples

I used similar method in my EDD Members add-on which is now multisite compatible. I also created a sample plugin how you could use this idea in your own projects.

That’s it for today, cheers!