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

Click the links below to jump to a specific part of the documentation.

Installation
Example 1. Just Get the Posts like WP_Query
Example 2. Global Network Search
Example 3. Get Posts only from the specific blogs in a network
Example 4. Query Network Posts with Pagination
Example 5. Get categories, post tags globally using get_terms() analogue

A few notes about plugin installation

This plugin will index all posts in your Multisite Install with custom fields meta_query and terms tax_query. The posts and terms index will be stored in the following database tables.

phpMyAdmin: MySQL database tables with posts and terms indexed from all sites in a network. — MySQL database with the global content inside phpMyAdmin

Now some notes about the plugin installation.

You can download the plugin by clicking the button in the top right part of the screen.
Once you uploaded the plugin on your website, you have to Network Activate it from Network Admin > Plugins page.
By default this plugin will index only the new posts you publish. If you want to add to the index your old posts, 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 important thing to know — when you rebuild your global index, it may take a time — how much — depends on the size of your Network. Maybe 10 minutes or maybe an hour.

You can find the index stats in your Network Dashboard.

You can find the plugin index statistics in Network Dashboard.

Example 1. Just Get the Posts like WP_Query

Let me introduce you the awesome Network_Query class — it works just like WP_Query but for all the network websites and supports all the same parameters + 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.

// 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() ) :
	echo '<ul>';
 
	// 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
		echo '<li class="post-' . $network_q->post->ID . ' blog-' . $network_q->post->BLOG_ID . '">
			<a href="' . get_permalink( $network_q->post->ID ) . '">' . $network_q->post->post_title . '</a>
		</li>';
 
		// restore_current_blog() to switch to the previous (!) website
		restore_current_blog();
	endwhile;
 
	echo '</ul>';
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().

Example 2. Global Network Search

The next very important feature of the plugin is the global search. And you can search all blogs 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.

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, you should also proceed to the Sites admin page and turn it on there as well. — 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.

With the code you also 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 );
```

Search for posts by their custom fields values — meta_query parameter of the Network_Query class.

$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 );

Search terms by part of their titles and descriptions.

$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 you each of the above examples and show how to replace default WordPress search form and results page with the global ones.

Everything else is like in WP_Query.

Example 3. Get Posts only from the specific blogs in a network. Choose post types to index / to query

Actually you can:

pass post_type or blog_id parameter to the Network_Query() class,
configure it in settings (globally for the whole network, or for each blog separately).

post_type: (string|array) It is default WP_Query parameter and I suppose you should already know how it works.

$args = array( 'post_type' => array( 'post', 'page' ) ); // get only posts and pages

blog_id: (int|array) This parameter allows to get posts from other blogs, just specify the IDs of the blogs you want to query posts from.

$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 websites.

You should also know one thing about post_type query parameter — it will work only for indexed post types, for example here I added to the index the product post type in the plugin settings:

Add the WooCommerce product post type to global network index.

And as I mentioned before, the post types for indexing can be configured individually for each network website. To do this, in your multisite dashboard go to Sites > All sites and click Configure link under the Indexing tab.

Here you can configure what post types to index for each blog individually. — For each blog you can choose what post types to index or completely disable indexing.

Example 4. Query Network Posts with Pagination

When you want to show posts from all blogs, it is very important to implement the pagination. And this is the simple 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.

Example 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 );
*/