Multiple Authors or Categories on the Same WordPress Site

If you are primarily interested in organizing your content into separate “sites” or “sections,” consider using multiple blog authors or categories on one WordPress site. If you have multiple authors on the same site, you can update your theme to style each author’s post archive to look like a unique site.

If you’d like to post behind-the-scenes–style content to a separate blog, you can create a post category for that content. You can use filters to keep that content from being included in the main index. You can link to the archive view for that one post category and style it separately to look like a “blog” for your larger site.

Custom Post Types

Another way to organize content to give a “separate sites” feel without actually setting up separate sites is to use CPTs. Similar to using different post categories, you can filter your main index to exclude certain CPTs and treat the archive view of some CPTs as a separate site.

Totally Separate Sites

If you are trying to share content across a few sites or get a few sites to work more seamlessly together, you might consider putting them on the same WordPress Multisite network. Alternatively, you can keep them as separate sites and use the REST API or tools like the WordPress Single Sign-On (SSO) plugin we developed to share content and users across each site (these are covered in detail in Chapter 10).

Multitenancy

If you like the concept of a shared repository for WordPress, theme, and plugin files but don’t want the shared database architecture of WordPress Multisite, you should look into multitenancy solutions. A simplistic view of multitenancy for WordPress is that it’s like using a symbolic link for your core WordPress folder and sharing those files across several WordPress installs on the same server or server cluster. In practice, it takes some work to get WordPress to respect this setup. A good place to start to learn more about multitenancy for WordPress are these talks by Cliff Seal on WordPress.tv.

Dashboard

Your network dashboard is set up very similarly to the default dashboard you are used to seeing on a standard WordPress installation except the Right Now widget displays links to quickly add new network sites or users. It also has two text boxes to search for specific users or sites. Just like the regular WordPress dashboard, you can completely customize this network dashboard using plugins or custom code.

Sites

Under Sites, you will manage all of the sites on your network. You can add any number of sites you like and even give your network users permission to create their own sites.

Adding a new site is pretty straightforward; at the top of the sites page, click the Add New button, or, on the Sites submenu, click Add New Link to get to the Add New Site page, where you’ll see the following fields:

Site address

Depending on how you set up your network, the address you enter will either be a subdomain or a subdirectory.

Site title

The title or name of your new site.

Administrator email

The email address of the administrator of your new site. This does not have to be your email address; it could be a client or a user for whom you’re setting up a new WordPress.

Click the Add Site button, and voilà, instant WordPress website. That sure saves a lot of time setting up a brand-new WordPress installation.

Users

All the sites you create on your network will pull from the same users pool. Technically, all users are stored in the wp_users table, and they each have user metadata tying them to one or more sites on your network. From the network users page, you can manage all the users on your sites, make any user a super administrator with rights to manage the entire WordPress Multisite network, and see what sites each user is a member of.

To get to the Add New User page, at the top of the Users page, click the Add New button, or, on the Users submenu, click the Add New link. On the Add New User page, you’ll see the following fields:

Username

The username of the new user you are creating. Remember, with all lowercase and this should have no spaces or special characters.

Email

The email address of the new user you are adding.

Once you click the Add User button, the user you added should receive an email with their username and password, which they can use to log in to the default top-level website with a default role of what you set a new user’s role to be. Adding users this way may not be ideal, as you will have to take another step to add them to specific subsites on your network. Depending on your situation, it might be easier for you to add new users to subsites directly from within that subsite, where you can add a new user the same way you would on a typical WordPress installation. If you try to add a user to a site and that username already exists on the network, you will receive a message indicating that the username already exists. At that point, you can add the user to the site by adding their username to the Add Existing User section and choosing a role and whether to send a confirmation email to that user.

Themes

These are all the themes available in the /wp-content/themes/ directory. You can control all of the themes the sites on your network can use. You must network-enable a theme before a site on your network can use it. If you don’t do so, it won’t even show up as an option to activate on a site’s Appearance → Themes page.

Plugins

These are all of the plugins available in the /wp-content/plugins/directory. You can network-activate plugins so that they will automatically run on all sites on your network, including new sites. Network-activated plugins will not show up on the individual site’s plugins page. In fact, unless you specifically enable the plugins menu on the network settings page (see next section), individual site administrators won’t even see the plugins page.

If you allow each site administrator to manage their own plugins, they will only be able to activate plugins that are already installed; they will not be able to install their own plugins. This is good because you want to know what plugins are available to all of the sites on your network. You don’t want a site administrator to be able to install any plugin they want or a custom plugin that could potentially have a negative effect on other sites on your network.

To add a new plugin at the network level, you would add it the same way you would on a normal installation of WordPress.

Settings

These settings are unlike the typical WordPress settings that you can update for a standard WordPress site; these are network-wide settings.

If you click the Settings link on the lefthand administrator navigation menu, you should see the following options:

Operational settings

• Network name

• Network administrator email

Registration settings

• Allow new registrations

• Registration notification

• Add new users

• Banned names

• Limited email registrations

• Banned email domains

New site settings

• Welcome email

• Welcome user email

• First post

• First page

• First comment author

• First comment URL

Upload settings

• Site upload space

• Upload file types

• Max upload file size

Menu settings

• Enable administration menus

Updates

Just as in a standard WordPress installation, you can update core WordPress or outdated plugins and/or themes all from this page. The beauty of a Multisite network is that you can update everything once, and across all the sites on your network. This is far more efficient than running updates on multiple WordPress installs. Update WordPress, plugins, and themes…done and done!

Networkwide Tables

Individual Site Tables

Every site added to your network is automatically given a blog_id when it is created. Each site also creates its own tables, adding its blog_id to each table name. Let’s say we are creating the first additional site on our network besides our main site. It would be given a blog_id of 2, and the following tables would be created in the database:

• wp_$blog_id_options

• wp_$blog_id_posts

• wp_$blog_id_postmeta

• wp_$blog_id_comments

• wp_$blog_id_commentsmeta

• wp_$blog_id_links

• wp_$blog_id_term_taxonomy

• wp_$blog_id_terms

• wp_$blog_id_term_relationships

As you can see, these are the same tables included in a standard WordPress installation except that they have a blog_id in their names. For every new site you create on your Multisite network, these tables will be duplicated with that new site’s blog_id.

Shared Site Tables

All users on your Multisite network share the same wp_users and wp_usermeta tables.

Users are associated with various sites on the network by a few user meta keys in the wp_usermeta table. If we added a new user to our second site on the network, these meta keys would be created:

• primary_blog

• wp_2_capabilities

• wp_2_user_level

A user can have only one primary_blog but can be tied to multiple sites with the capabilities and user_level meta keys. In the default WordPress installation and on the top-level site of a Multisite network, these meta keys are stored as wp_capabilities and wp_user_level. When you add users to sites on the network, new meta key records are created for each user for the blog_id you are adding them to with whatever role you added them as.

Gravity Forms User Registration Add-On

Add-On is a great plugin if you want to easily allow users to register to various sites on your Multisite network via a Gravity Forms shortcode or a widget you can place anywhere. It can also be configured to create a new site on your Multisite network when a user creates their account. This could be useful if you want to trigger the creation of a new site for a new user joining your Multisite network.

Member Network Sites Add-On for Paid Memberships Pro

Add-On for Paid Memberships Pro allows you to charge users to create new sites on your network. We cover how to set this up in Chapter 15.

More Privacy Options

Once installed, the WordPress Privacy plugin adds further levels of privacy to your Reading settings. These new levels are Network Users Only, Blog Members Only, and Admins Only, which makes your site visible to only whichever of these groups you choose.

Multisite Global Media

The Multisite Global Media plugin shares a global Media Library across sites on the network. Basically it uses the Media Library of a specific site so any of the sites on a network can access the same shared resources.

Multisite Plugin Manager

If you have a network of sites and you want to give access to site administrators to manage some of the plugins they are using, the Multisite Plugin Manager makes that very easy to manage. The plugin provides a network administrator UI for setting sitewide defaults for each site, you can also override the sitewide defaults for individual sites. There are three main settings for managing your plugins:

• Auto Activation

• User Control

• Mass Activation/Deactivation

Multisite Global Search

Multisite Global Search allows you to search across the multiple sites on your network and receive results from all those sites. This plugin also comes with a built-in widget that can be used to display the search bar in the sidebar. Both the widget and the results page come with a customizable stylesheet. The plugin uses shortcodes, enabling you to insert the search in any templates you choose.

Multisite Robots.txt Manager

Multisite Robots.txt Manager allows you to create custom robots.txt files for each website on the network and then quickly publish those files to the network or a website. This plugin will also instantly add sitemap URLs to all the robots.txt files. In addition, it will automatically detect 404 or old robots.txt files and allows for easy correction once identified.

NS Cloner: Site Copier

There are a few plugins available to copy sites on your network but NS Cloner: Site Copier is a favorite. This plugin is very useful for anyone who needs to duplicate the settings and content from one site to another site on the network. If you are pumping out similar websites, you can create a “template” site all preconfigured exactly how you want it (theme settings, plugin settings, default content, etc.). You can put placeholders into your template site content so when you clone it to make a new site, an action is taken to automatically update these placeholders with whatever values you want. Why start with a blank site where you would have to reconfigure everything? Just clone whatever site you want and use it as a starting point. Save time and money!

WP Multi Network

The WP Multi Network plugin allows one WordPress installation to have multiple networks, with each network having its own subsites. Build a network of networks! Remember how when Multisite is activated, it inserts just one row in the wp_site table? The WordPress Multi Network plugin basically allows you to add new rows to that table and have new subsites set up under a different site_id.

$blog_id

After reviewing the tables Multisite creates, we know that each site has a unique blog_id. You can use this ID to point WordPress to the site you want to retrieve data from or push data to.

The global variable $blog_id will automatically be set to the site you are on unless changed with the switch_to_blog() function. This variable will be useful when writing custom Multisite functionality:

function wds_show_blog_id(){
    global $blog_id;
	echo 'current site id: ' . $blog_id;
}
add_action( 'init', 'wds_show_blog_id' );

If you are on the top-level site or original site on your network, you should see 1. If you are on the second site you created on your network, you should see 2.

is_multisite()

This function checks to see whether WordPress Multisite is enabled. If you are not running Multisite and try to use one of its functions, you may get an error. Always check that Multisite is enabled before executing Multisite-specific code:

function wds_run_multisite_functions(){
	if ( is_multisite() )
		echo 'Run whatever WordPress Multisite functionality you want!';
}
add_action( 'init' , 'wds_run_multisite_functions' );

get_current_blog_id()

This function returns the blog_id that you are currently on. The function itself is literally two lines of code:

// core function get_current_blog_id
function get_current_blog_id() {
	global $blog_id;
	return absint($blog_id);
}

get_current_blog_id() is located in wp-includes/load.php.

switch_to_blog( $new_blog )

This function switches the current blog to any blog you specify. This function is useful if you need to pull posts or other information from other sites on your network. You can switch back afterward using restore_current_blog(). Autoloaded options and plugins are not switched with this function. This function accepts one parameter, $new_blog, which is a required integer of the ID of the site to which you want to switch.

If we want to switch the site we’re currently on, we could run the following code in any plugin function or theme file:

echo 'current site id: ' . get_current_blog_id() . '<br>';
switch_to_blog(2);
echo 'new current site id: ' . get_current_blog_id();

The code should output something like:

current site id: 1
new current site id: 2

switch_to_blog() is located in wp-includes/ms-blogs.php.

restore_current_blog()

Use this function to restore the current site, after calling the switch_to_blog() function. This function doesn’t accept any parameters.

If we want to restore a switched site, we can run the following code:

echo 'current site id: ' . get_current_blog_id() . '<br>';
switch_to_blog(2);
echo 'new current site id: ' . get_current_blog_id() . '<br>';
restore_current_blog();
echo 'original site id: ' . get_current_blog_id();

The code should output something like this:

current site id: 1
new current site id: 2
original site id: 1

restore_current_blog() is located in wp-includes/ms-blogs.php.

get_blog_details( $fields = null, $get_all = true )

This function gets all the available details of a site and accepts two parameters:

$fields

The ID or name of a specific blog, or an array of blog IDs or blog names. Defaults to the current blog ID.

$getall

Default is set to true to return all available data in the object.

This function returns an object of the following variables:

blog_id

The ID of the blog being queried.

site_id

The ID of the site this blog ID is attached to.

domain

The domain used to access the blog.

path

The path used to access the site.

registered

Timestamp of when the blog was registered.

last_updated

Timestamp of when the blog was last updated.

public

1 or 0 indicating whether the blog is public or not.

archived

1 or 0 indicating whether the blog is achieved or not.

mature

1 or 0 indicating whether the blog has adult content or not.

spam

1 or 0 indicating whether the blog has been marked as spam or not.

deleted

1 or 0 indicating whether the blog has been deleted or not.

lang_id

ID of the language the blog is written in.

blogname

The name of the blog.

siteurl

The URL of the site the blog belongs to.

post_content

The number of posts in the blog.

To display the entire object returned by this function, we would run the following code:

$details = get_blog_details( 1 );
echo '<pre>';
print_r($details);
echo '</pre>';
echo 'Site URL:' . $details->siteurl;
echo 'Post Count:' . $details->post_count;

The code should return a similar object and string:

stdClass Object
(
    [blog_id] => 1
    [site_id] => 1
    [domain] => schoolpress.me
    [path] => /
    [registered] => 2013-03-01 00:23:26
    [last_updated] => 2013-04-01 14:18:59
    [public] => 1
    [archived] => 0
    [mature] => 0
    [spam] => 0
    [deleted] => 0
    [lang_id] => 0
    [blogname] => School Press
    [siteurl] => http://schoolpress.me
    [post_count] => 10
)

This site URL is http://schoolpress.me, and it has 10 posts.

get_blog_details() is located in wp-includes/ms-blogs.php.

update_blog_details( $blog_id, $details = array() )

This function updates the details for a blog and accepts two parameters:

$blog_id

A required integer of the ID of the blog you want to update.

$details

A required array of any of the fields from the blog’s table as keys with any values you want to update.

To mark a particular site as deleted, we would run the following code:

update_blog_details( 2, array( 'deleted' => '0' ) );

update_blog_details() is located in wp-includes/ms-blogs.php.

get_blog_status( $id, $pref )

This function is similar to the get_blog_details() function, except instead of returning an object of all of the fields in the wp_blogs table, it returns the value of one specific field:

$id

A required integer of the ID of the site you want to return a wp_blogs field from.

$pref

A required string of the field name from the wp_blogs table.

To show when the current site was registered, we could run the following code:

echo get_blog_status( get_current_blog_id(), 'registered' );

get_blog_status() is located in wp-includes/ms-blogs.php.

update_blog_status( $blog_id, $pref, $value )

This function is similar to the update_blog_details() function, except instead of updating an array of fields in the wp_blogs table, it updates one specific field:

$blog_id

A required integer of the ID of the site you want to update a wp_blogs field for.

$pref

A required string of the field name from the wp_blogs table you want to update.

$value

A required string of the field value you want to update.

If we wanted to mark the current site as deleted, we could run the following code:

update_blog_status( get_current_blog_id(), 'deleted', '1' );

update_blog_status() is located in wp-includes/ms-blogs.php.

get_blog_option( $id, $option, $default = false )

This function saves you the hassle of using switch_to_blog() and then using the regular WordPress get_option() function or writing a custom SQL query if you want to grab an option from a specific site. This function returns an option value from any site on your network by passing in the following parameters:

$id

A required integer of the ID of the site you want to get an option from. You can pass in null if you want to get an option from the current site.

$option

A required string of the option name you want to get.

$default

Optional string to return if the function does not find a matching option.

To get the admin_email of a particular site, run the following code:

echo 'The admin email for site id 2 is ' . get_blog_option( 2, 'admin_email' );

get_blog_option() is located in wp-includes/ms-blogs.php.

update_blog_option( $id, $option, $value )

This function updates any option for a particular site and accepts three parameters:

$id

A required integer of the ID of the site you want to update an option on.

$option

A required string of the option name you want to update.

$value

A required string of the option value you want to update.

To update the admin_email of a particular site, we would run the following code:

update_blog_option( 2, 'admin_email', '[email protected]' );

update_blog_option() is located in wp-includes/ms-blogs.php.

delete_blog_option( $id, $option )

This function deletes any option from a particular site and accepts two parameters:

$id

A required integer of the ID of the site you want to delete an option on.

$option

A required string of the option name you want to delete.

To delete a custom site option from a particular site, we run the following code:

delete_blog_option( 2, 'wds_custom_option' );

delete_blog_option() is located in wp-includes/ms-blogs.php.

get_blog_post( $blog_id, $post_id )

This function gets a post from any site on the network and accepts two parameters:

$blog_id

A required integer of the blog ID of the site you want to get a post from.

$post_id

A required integer of the post ID of the post that you want to get.

To get the post title of the third post from the second site on our network, we could run the following code:

$post = get_blog_post( 2, 3 );
echo $post->post_title;

get_blog_post() is located in wp-includes/ms-functions.php.

add_user_to_blog( $blog_id, $user_id, $role )

This function adds a user to any site on the network with a specified user role and accepts three parameters:

$blog_id

A required integer of the blog ID of the site you want to add the user to.

$user_id

A required integer of the user ID of the user that you want to add to the site.

$role

A required string of the role you want the user to have.

This function will return true if a user was added successfully; and if not, it will return a WP_Error.

If we wanted to add a specific user to the second site on our network with a role of Administrator, we could run the following code:

add_user_to_blog( 2, 5, 'administrator' );

add_user_to_blog() is located in wp-includes/ms-functions.php.

wpmu_delete_user( $user_id )

This function deletes a user from the entire network, and deletes all posts authored by that user.

$user_id

A required integer of the user ID of the user that you want to delete.

This function returns true if the user was successfully deleted; if not, it returns false.

When Multisite is active, the regular wp_delete_user() function will remove a user from the current site instead of deleting the user entirely. So it is important to make sure you use the wpmu_delete_user() function and hook into both the wp_delete_user and wpmu_delete_user hooks in multisite situations. If you are coding something that needs to run in Multisite or in single-site settings, you can do this with the is_multisite() function first:

if ( is_multisite() ) {
  wpmpu_delete_user( $user_id );
} else {
  wp_delete_user( $user_id );
}

wpmu_delete_user() is located in wp-includes/ms-functions.php.

create_empty_blog( $domain, $path, $weblog_title, $site_id = 1 )

This function creates a new site on the network after making sure it doesn’t already exist. It’s also used by the network admin, to add new sites. It accepts four parameters:

$domain

A required string of the domain of the new blog.

$path

A required string of the path of the new blog.

$weblog_title

A required string of the title or name of the new blog.

$site_id

An optional integer of the site ID associated with the new blog. The default is 1.

If we want to add a new site to our network, we can run the following code:

create_empty_blog( 'someteacher.schoolpress.me', '/', 'Mr. Some Teacher' );

create_empty_blog() is located in wp-includes/ms-functions.php.

Functions We Didn’t Mention

We didn’t cover every Multisite function, but we did cover most of the important ones. Though that depends on what you are trying to do. To find all available Multisite functions, look in the source code! You can find WordPress Multisite functions in the following files:

• wp-admin/includes/ms.php

• wp-includes/ms-blogs.php

• wp-includes/ms-functions.php

For more information, check out the “Multisite functions” section of the WordPress Codex.