This document discusses developing plugins for WordPress Multisite networks. Key points: - Multisite allows a single WordPress installation to manage multiple sites from a shared database and files. There is one "main" site and many "sub-sites". - Plugins can be activated network-wide or on individual sites. Plugin developers need to consider how settings and capabilities will work for super admins, sub-site admins, and regular users. - The document provides examples of functions to determine the current site, user roles, and other context needed to build Multisite-aware plugins. It also discusses strategies for updating options across the entire network.

1. Developing for MultiSite

2. Freelance WordPress Developer
Owner and Lead Developer at
PhotographyBlogSites.com
martythornley.com @martythornley
A Little About Me

3. Standard WordPress
Single site for you
Single site for client
MultiSite
Series of personal sites
Multiple client sites
Signups open to the public
What is
MultiSite?

4. Single WordPress installation
One “main site”
Lots of “sub-sites”
Network of Many Sites
What is
MultiSite?
Single database
Single set of core files
Shared Plugins folder
Shared Themes folder
Shared Files and DB

5. Manages the network
There should be only 1 ( or very few )
Installs and updates themes, plugins
“Super Admin” user
MultiSite
Admin
Can only access their site(s)
Can not install, update or edit:
Core, plugins, themes, users
“Administrator” users

6. Admin area for each site
Accessed by users of that site
Settings and content for that site
every-site/wp-admin/
MultiSite
Admin Only the Super Admin can access
Network-wide settings
Edit configurations for each site
Add and edit sites and users
Install and activate plugins & themes
/wp-admin/network/

7. Plugins shared by all sites
Can be network activated
Can be activated site by site
/plugins/
Plugins
and
MultiSite always on
used on all sites
no activation hook
no deactivation hook
/mu-plugins/

8. Network
Site-by-site
Settings
Plugin
Developers
Need to
Think
Ahead Network admin
Sub-site admin
Menus
Super Admins
Admins
Users

9. BackWPup
Sucuri Scanner
W3 Total Cache
WordPress SEO
Let’s look at some Plugins

10. Standard Network Sub-Site
The Plugins Screen

11. Standard Network Sub-Site
Admin Menus
No Sucuri Menu
No BackWPup Menu

12. MultiSite - only in Network Admin
BackWPup

13. BackWPup
Can add user capabilities
Gives Non Super Admins
Access to /network/ admin!

14. BackWPup - Ideas
Let each site back up their own stuff?
Let Super Admins determine how often they can do that?

15. Standard WordPress
Sucuri Scanner

16. MultiSite - No Network Admin
Sucuri Scanner

17. MultiSite - SubSite as Super Admin
Sucuri Scanner

18. MultiSite - SubSite as Admin User
Sucuri Scanner

19. Sucuri Scanner
MultiSite - SubSite as Admin User

20. Sucuri Scanner - Ideas
Provide network admin screen so settings can be set site wide.
Most settings for this plugin should be network wide.
Right now, you need to go into each site and set it up again, even
if you want to use the same settings.

21. W3 Total Cache
Same screen - Standard, Network and SubSite

22. W3 Total Cache - Ideas
Are these network settings or site settings?
Most settings for this plugin should be network wide.
Probably only needs a network admin screen.
Each site should clear its own cache but not the entire cache.

23. WordPress SEO
Standard WordPress

24. Network Admin
WordPress SEO

25. SubSite - As Super Admin
WordPress SEO

26. SubSite - As Admin
WordPress SEO

27. Edit Files
WordPress SEO

28. Edit Files
WordPress SEO

29. Allow super admins option to control settings once.
Still have subsite settings for Facebook, Twitter, etc.
Why "Edit Files" within a subsite?
Each subsite can not technically add or remove plugins so why
advertise to them? Brand it, but don't advertise.
WordPress SEO - Ideas

30. Navigating MultiSite

31. Knowing
Where
We Are
is_multisite()
is_main_site()
is_admin()
is_network_admin()

32. Knowing
Who
We Are
is_super_admin()
is_user_logged_in()
$current_user = wp_get_current_user();
if( current_user_can( ‘edit_themes’ ) )

33. What
Sub-Site
are
We In?
global $blog_id;
$id = get_current_blog_id();
$details = get_blog_details( $id );

34. URL
Functions
home_url();
site_url();
admin_url();
network_home_url();
network_site_url();
network_admin_url();
$url = get_home_url( $blog_id );
$url = get_site_url( $blog_id );
$url = get_admin_url( $blog_id );

35. WP
Constants
WP_CONTENT_DIR
WP_CONTENT_URL
WP_PLUGIN_DIR
WP_PLUGIN_URL
WPMU_PLUGIN_DIR
WPMU_PLUGIN_URL

36. Site-by-Site Settings
add_option( $option , $value );
update_option( $option , $value );
get_option( $option );
add_blog_option( $blog_id , $option , $value );
update_blog_option( $blog_id , $option , $value );
get_blog_option( $blog_id , $option );

37. Network Settings
add_site_option( $option , $value );
update_site_option( $option , $value );
get_site_option( $option );

38. Adding Menus
add_action( ‘admin_menu’ , ‘add_my_menu’ );
add_action( ‘network_admin_menu’ , ‘add_my_menu’ );
function add_my_menu() {add_menu_page( $page_title , $menu_title , $capability ,
$menu_slug , $function , $icon_url , $position );add_submenu_page( $parent_slug , $page_title , $menu_title ,
$capability , $menu_slug , $function );}
}
}

39. Admin users lose a lot of capabilities.
User Capabilities
update_core
update_plugins
update_themes
install_plugins
install_themes
delete_themes
edit_plugins
edit_themes
edit_users
create_users
delete_users
unfiltered_html

40. The register_setting functions work but ONLY on
single site settings.
Network settings need to be processed and saved.
Saving Network Settings
add_action( ‘admin_init’ , ‘process_and_save_my_settings’ );

41. Making Use of It All

42. Network Options Hide Stuff
Add a network admin menu pageAllow super
admins to save a setting
update_site_option( ‘allow_sites_to_see_stuff’ , true );

43. Network Options Hide Stuff
Check the site_option Only do stuff if allowed by
site_option
if ( get_site_option( ‘allow_sites_to_see_stuff’ ) ) {
// do stuff
}

44. Update Options Site-By-Site
Based on Network Option
Super admin chooses a setting
( like a permalink structure )
ALL sub-sites get the same setting.
Lots of BAD ways to do this.

45. update_site_option( ‘awesome_site_option’ , $value );
$blogs = $wpdb->get_results( SELECT blog_id FROM {$wpdb->blogs} … a bunch of other stuff ...
$value = get_site_option( ‘awesome_site_option’ );
foreach ( $blogs as $blog ) {
update_blog_option( $blog['blog_id'] , ‘option_name’ ,
$value );
}
Do NOT do this!
Will cycle through EVERY blog, which could be 1,000‘s.

46. A Better Way
update_site_option( ‘awesome_site_option’ , $value );
add_action( ‘init’ , ‘update_my_site_options’ );
function update_my_site_options() {
$value = get_site_option( ‘awesome_site_option’ );
update_option( ‘awesome_option’ , $value );
}
Only happens as each site loads. BUT... happens every page load.

47. An Even Better Way
update_site_option( ‘awesome_site_option’ , $value );
update_site_option( ‘awesome_site_option_updated’ , time() );
add_action( ‘init’ , ‘update_my_site_options’ );
function update_my_site_options() {
$net_time = get_site_option( ‘awesome_site_option_updated’ );
$site_time = get_option( ‘awesome_option_updated’ );
if ( $net_time > $site_time ) {
$value = get_site_option( ‘awesome_site_option’ );update_option( ‘awesome_option’ , $value );
update_option( ‘awesome_option_updated’ , time() );
}}
Checks times first. BUT... still happens every page load.

48. Maybe the Best Way?
add_filter( ‘pre_option_posts_per_page’ , ‘network_limit_posts’ );
function network_limit_posts( $num_posts ) {
if ( $network_posts = get_site_option( ‘network_post_limit’ ) ) {
return $network_posts;
} else {
return $num_posts;
}
}
Only looks for site_option when option is needed.

49. What settings should be network-wide?
What settings should be site-by-site?
Settings
What should be in the network admin?
What should be in the site admin?
Menus
What should Super Admins see?
What should Admins see?
Users
Ask

50. Questions

51. theuproots.com
PhotographyBlogSites.com martythornley.com
slideshare.net/MartyThornley/developing-formultisite