This document discusses different ways of storing and retrieving data in WordPress including options, transients, theme mods, site options, site transients, user settings, user options, and user meta. Options and transients store data in the database. Transients are like options but can expire. Theme mods store theme-specific data. Site options and site transients work similarly but are for multisite installations. User settings store non-persistent data while user options and user meta work similarly but are associated with individual users.

1. Options, and Transients,
and Theme Mods — Oh my!
WordCamp St. Louis
March 1, 2014

2. Konstantin Obenland
Chairman Of Height at Automattic
!
@obenland
konstantin.obenland.it

3. get_option() queries the
database every time it is called.
True or False?

4. Transients are Options with an
expiration date.
True or False?

5. wp-includes/option.php

6. Options vs. Transients
Choose one.

7. Options API

8. A simple and way of storing
arbitrary data in the database.

9. get_option()
Is it in $all_options?
Yes
No
Is it in $wp_cache?
Return value.
Yes
No
Is it in the database?
Yes
No
Add to $wp_cache
Return $default.

10. What are Notoptions?

11. Well, they are not options!

12. get_option()
Is it in $all_options?
Yes
No
Is it in $wp_cache?
Return value.
Yes
No
Is it in the database?
Yes
No
Add to $wp_cache
Return $default.

13. get_option()
Is it in $notoptions?
Yes
No
Is it in $all_options?
Yes
No
Is it in $wp_cache?
Return value.
Yes
No
Is it in the database?
Yes
No
Add to $wp_cache
Add to $notopions
Return $default.

14. Transients API

15. A simple way of storing cached data.

16. Transients API
↓
Object Cache API
↓
WP_Object_Cache

17. They may use the Options API.

18. They can optionally expire.

19. function get_transient( $transient ) {
!
if ( wp_using_ext_object_cache() ) {
return wp_cache_get( $transient, 'transient' );
!
} else {
// Check wp_load_all_options()
!
}
}
return get_option( $transient_option );

20. function set_transient( $transient, $value, $expiration = 0 ) {
// Check for external object cache and use it.
// Check DB for existing value and update expiration.
// Add an option with the expiration of this transient.
// Add the transient value to the DB.
}

21. function get_my_data() {
$data = get_transient( 'my_data' );
if ( false === $data ) {
$data = $wpdb->get_results( $query );
set_transient( 'my_data', $data, DAY_IN_SECONDS );
}
!
// Do something with $data.
!
}
return $data;

22. function get_my_data() {
$data = wp_cache_get( 'my_data', 'my_group' );
if ( false === $data ) {
$data = $wpdb->get_results( $query );
wp_cache_set( 'my_data', $data, 'my_group', DAY_IN_SECONDS );
}
!
// Do something with $data.
!
}
return $data;

23. External Object Cache

24. By default, the built-in the object cache
is non-persistent.

25. Pluggable, to allow for
third party object caches.

26. Most popular: APC & Memcached
Source: Grokking the WordPress Object Cache; Tollmanz, Zack.

27. Recommended Reading
http://vip.wordpress.com/documentation/caching/
http://tollmanz.com/core-caching-concepts-in-wordpress/
http://tollmanz.com/grokking-the-wp-object-cache/
http://scotty-t.com/2012/01/20/wordpress-memcached/

28. Theme Mods

29. set_theme_mod( $name, $value );
get_theme_mod( $name, $default = false );
remove_theme_mod( $name );
!
get_theme_mods();
remove_theme_mods();

30. function get_theme_mod( $name, $default = false ) {
$mods = get_option( 'theme_mods_' . get_option( 'stylesheet' ) );
!
if ( isset( $mods[ $name ] ) )
return $mods[ $name ];
!
return $default;
}

31. Site Options & Site Transients

32. Uses the sitemeta table on Multisite.

33. User Settings & User Options

34. User Settings

35. User Settings
Primary examples are the expansion/collapse of the admin menu, and
switching between text and visual. These can happen without a form
submit, and you wouldn't want to fire an XHR request every time just to
save the previous state.
—Andrew Nacin

36. User Options
Uses the User Meta API

37. But!

38. User Options vs. User Meta

39. Thank you!

40. Konstantin Obenland
@obenland
konstantin.obenland.it