How it Works

This plugin will index all posts in your Multisite Install with custom fields (so you can use meta_query) and terms (for tax_query). The posts index is going to be stored in separate database tables wp_network_posts and wp_network_postmeta, the terms index will be stored in wp_network_terms, wp_network_term_relationships and wp_network_term_taxonomy.

These tables are identical to original WordPress tables but also have a BLOG_ID column.

The whole indexing process is performed in the background with the help of Cron – that’s the key why you’ll never face any performance issues even if your network has hundreds of sites and thousands of posts.

Once the index is ready you can pull any content from it using Network_Query or network_get_terms() for example, ordering it any way you want or perform a search in it.

Below let me guide you through the installation process and then we take a look at examples.

Installation

Once you upload the plugin to your website, please go to Network Admin > Plugins and Network Activate it from that page.

By default the plugin will index a post only when it is published or updated. If you want to add to the index your old posts, please go to Settings > Index and then switch to Rebuild Index tab.

Go to the Rebuild Index tab if you want to add your old posts to the network index
That’s where you can completely rebuild the index. One thing to know — when you rebuild your global index, it may take some time, how much — depends on the size of your Network. Maybe 10 minutes or maybe an hour.

But before rebuilding the index you can also configure what post types and post statuses you would like to index:

configure in settings what post types to index
Please also take a look at “Remove indexed posts older than” option. If you set 1 year there, but all your posts are older than 2 years, then nothing will be indexed.

You can configure it for specific sites as well.

WordPress multisite site index settings

When your posts appear in index, you can see them in Network Dashboard.

You can find the plugin index stats in Network Dashboard

So, How to Get All Network Posts in a One Query?

Now let’s get straight to the examples.

1. Get Posts just like with WP_Query

Let me introduce you the awesome Network_Query class — it works like WP_Query but for all the network websites and supports all the same parameters (documentation) + blog_id parameter (I will show how this parameter works in the next example).

Now let’s begin with something simple.

$network_q = new Network_Query( 'posts_per_page=5' ); // display 5 latest global posts
 
if( $network_q->have_posts() ) :
 
	// run the loop for each post
	while( $network_q->have_posts() ) : $network_q->the_post();
 
		// we just get post titles here
		// but you can print_r( $network_q->post ) to view all post data
		echo '<h3>' . $network_q->post->post_title . '</h3>';
 
	endwhile;
 
else :
	echo 'No posts found for this criteria';
endif;

Something a little more interesting.

<?php
// Network_Query parameters
$args = array(
	'posts_per_page' => 14,
	'orderby' => 'name',
	'order' => 'ASC',
	'meta_query' => array(
		array(
			'key' => 'featured', // we display only posts with custom field 'featured' = 'on'
			'value' => 'on'
		)
	)
);
 
$network_q = new Network_Query( $args );
 
// if there are posts, then print <ul>
if( $network_q->have_posts() ) :
	?><ul><?php
 
	// run the loop
	while( $network_q->have_posts() ) : $network_q->the_post();
 
		// the get_permalink() function won't work without switch_to_blog()
		// you can use network_get_permalink() instead but it is a little slower
		switch_to_blog( $network_q->post->BLOG_ID );
 
		// you can obtain the post title from $network_q->post object
		?>
			<li class="post-<?php echo $network_q->post->ID ?> blog-<?php echo $network_q->post->BLOG_ID ?>">
				<a href="<?php echo get_permalink( $network_q->post->ID ) ?>"><?php echo $network_q->post->post_title ?></a>
			</li>
		<?php
 
		// restore_current_blog() to switch to the previous (!) website
		restore_current_blog();
	endwhile;
 
	?></ul><?php
endif;
network_reset_postdata(); // add it after the loop if you plan to use Network_Query multiple times on the page

Some comments:

  • In the loop we obtain $network_q->post object — it has all WP_Post object parameters with $network_q->post->BLOG_ID, the ID of the network blog.
  • If you need to do something and the WP_Post object is not enough for your purposes, then use the switch_to_blog() function – it allows you run any WordPress loop functions like get_the_post_thumbnail()get_permalink() etc. Just do not forget to pass a Post ID into these functions.
  • We need restore_current_blog() to cancel the switch_to_blog() effect, the function switches us to the previous blog — so, use it in a loop.
  • The network_reset_postdata() works similar to wp_reset_postdata().

The next very important feature of the plugin is the global search. And you can search all sites not for only posts and pages (post types), you can also perform search for categories and post tags (taxonomies).

Starting with the plugin version 4.4 it is even not required to do anything in the code in order to enable the global search. Just go to Settings > Index and then proceed to the Globals tab.

Implementing a global search in WordPress multisite network
If you use the Widget option, the Global Search Widget will appear in Appearance > Widgets, or if you would like to replace the default search results with the global ones, you should proceed to the Sites admin page and turn this feature on there for each site individually.

Or you can use WordPress default search engine across the whole network. I mean s parameter of the Network_Query class.

$args = array(
	's' => 'Search query'
);
 
$query_search = new Network_Query( $args );

It is also possible to search for posts by their custom fields values — meta_query parameter of the Network_Query class will help you with that.

$args = array(
	'meta_query' => array(
		'relation' => 'OR',
		array(
			'key'     => 'key1', // key1 must contain "wordcamp"
			'value'   => 'wordcamp',
			'compare' => 'LIKE'
		),
		array(
			'key'     => 'key2', // OR key2 must contain "wordpress"
			'value'   => 'wordpress'
			'compare' => 'LIKE'
		)
	)
);
 
$query_search = new Network_Query( $args );

Searching terms by part of their titles and descriptions looks like this:

$network_cats = network_get_terms( 'category', 'description__like=wordcamp' );
$network_cats = network_get_terms( 'category', 'name__like=wordpress' );

In full global search tutorial I will explain each of the above examples and show how to replace default WordPress search form and search results page with the global ones.

Everything else is like in WP_Query.

3. Get posts from the specific blogs in a network. Choose post types to query

In this examples we are going to work with post_type and blog_id parameters of the Network_Query class but I would like to remind you that you can exclude specific blogs and post types in plugin settings as well, I described it in the installation part.

$args = array( 'post_type' => array( 'post', 'page' ) ); // get only posts and pages
$args = array(
	'post_type' => 'post', // only posts
	'blog_id' => array( 1, 3 ) // only from blogs 1 and 3
);

Do not know where to get blog ID? Not a problem — my plugin will show a blog ID column in your network dashboard Sites > All sites.

Column with Blog ID on the All Sites page
Plugin automatically adds the Blog ID column to the table with the all sites.

You should also know one thing about post_type query parameter — it will only work for indexed post types. If a post type is excluded from the index in plugin settings (check installation part), it will be ignored by post_type parameter as well.

4. Query Network Posts with Pagination

When you want to show posts from all blogs, it is very important to implement the pagination. And below is the simplest way how you can do it:

global $wp_query;
 
// get the current page number from $wp_query, I mean the URL parameter, i.e. /page/2
$current_page = ( get_query_var( 'paged' ) ) ? get_query_var( 'paged' ) : 1; // you can use $wp_query->query['paged'] as well
 
// similiar to query_posts()
$network_q_posts = network_query_posts( array( 'posts_per_page' => 3, 'paged' => $current_page ) );
 
// run the loop
foreach( $network_q_posts as $network_q_post ) :
 
	// we need it to work with get_the_post_thumbnail() and get_permalink()
	switch_to_blog( $network_q_post->BLOG_ID );
 
	echo '<li>' . get_the_post_thumbnail( $network_q_post->ID ) . '<a href="' . get_permalink( $network_q_post->ID ) . '">' . $network_q_post->post_title . '</a></li>';
 
	// switch back
	restore_current_blog();
endforeach;
 
// we should change the global $wp_query value to work correctly with pagination
$wp_query = $GLOBALS[ 'network_query' ];
 
// I use the popular WP PageNavi plugin
wp_pagenavi();
 
// reset the $wp_query
wp_reset_query();

If you have problems with this example, you can read full detailed tutorial here.

5. Get categories, post tags globally using get_terms() analogue

My plugin allows you to get not only post types but taxonomy terms as well. It can be implemented easily with network_get_terms() (click the link to view the detailed tutorial).

And here is a simple example:

$network_categories = network_get_terms( 'category', 'orderby=name&hide_empty=0' );
 
if( $network_categories ){
	echo '<select>';
	foreach ( $network_categories as $network_category ){
		echo "<option value='{$network_category->term_id}'>{$network_category->name}</option>";
	}
	echo '</select>';
}
/*
in this example is obvious that
$network_category->name - category name,
$network_category->term_id - category global unique ID across the network
but you can get more info about the category if you look into the object using
print_r( $network_category );
*/