Problem with pagination

README.md

@@ -0,0 +1,44 @@
+# WordPress Query Multisite
+
+This is a custom version of [WP_Query_Multisite](https://github.com/ericandrewlewis/WP_Query_Multisite), by [ericandrewlewis](https://github.com/ericandrewlewis), to support multisite post queries but without changing the class declaration, we will use the good ol' **WP_Query**. Just by entering the custom query var **multisite => 1** on your query args and your query is now global.
+
+-----------------
+
+## Example usage
+
+```php
+$query = new WP_Query( array('multisite' => '1' ) );
+while($query->have_posts()) : $query->the_post();
+    echo $blog_id . get_the_title() . "<BR>";
+endwhile; 
+wp_reset_postdata();
+```
+
+To modify what sites are queried, create a 'sites' element in the $args in the constructor parameter, with a sub-element of either 'sites__in' or 'sites__not_in', which will be an array similar to 'posts__in' in the WP_Query object. 
+
+```php
+$args = array(
+	'multisite' => 1,
+	'sites__in' => array( 1, 2, 3, 5)
+);
+$query = new WP_Query( $args );
+while($query->have_posts()) : $query->the_post();
+    echo $blog_id . get_the_title() . "<BR>";
+endwhile; 
+wp_reset_postdata();
+```
+
+### Automatic multisite search example
+
+On your functions.php:
+
+```php
+include_once(TEMPLATEPATH . '/path/to/multisite-query.php');
+
+function my_multisite_search($query) {
+	if(!is_admin() && $query->is_main_query() && $query->is_search) {
+		$query->set('multisite', 1);
+	}
+}
+add_action('pre_get_posts', 'my_multisite_search');
+```

index.php

@@ -1,100 +1,123 @@
 <?php
 
-class WP_Query_Multisite extends WP_Query{
-
-
-	var $args;
-
-	function __construct( $args = array() ) {
-		$this->args = $args;
-		$this->parse_multisite_args();
-		$this->add_filters();
-		$this->query($args);			  
-		$this->remove_filters();
+class WP_Query_Multisite {
 
-	}
-
-	function parse_multisite_args() {
-		global $wpdb;
-
-		$site_IDs = $wpdb->get_col( "select blog_id from $wpdb->blogs" );
-
-		if ( isset( $this->args['sites']['sites__not_in'] ) )
-			foreach($site_IDs as $key => $site_ID )
-				if (in_array($site_ID, $this->args['sites']['sites__not_in']) ) unset($site_IDs[$key]);
-
-		if ( isset( $this->args['sites']['sites__in'] ) )
-			foreach($site_IDs as $key => $site_ID )
-				if ( ! in_array($site_ID, $this->args['sites']['sites__in']) ) 
-					unset($site_IDs[$key]);
-
-
-		$site_IDs = array_values($site_IDs);
-		$this->sites_to_query = $site_IDs;
+	function __construct() {
+		add_filter('query_vars', array($this, 'query_vars'));
+		add_action('pre_get_posts', array($this, 'pre_get_posts'), 100);
+		add_filter('posts_clauses', array($this, 'posts_clauses'), 10, 2);
+		add_filter('posts_request', array($this, 'posts_request'), 10, 2);
+		add_action('the_post', array($this, 'the_post'));
+		add_action('loop_end', array($this, 'loop_end'));
 	}
 
-	function add_filters() {
-
-			add_filter('posts_request', array(&$this, 'create_and_unionize_select_statements') );
-			add_filter('posts_fields', array(&$this, 'add_site_ID_to_posts_fields') );
-			add_action('the_post', array(&$this, 'switch_to_blog_while_in_loop'));
-
+	function query_vars($vars) {
+		$vars[] = 'multisite';
+		$vars[] = 'sites__not_in';
+		$vars[] = 'sites__in';
+		return $vars;
 	}
-	function remove_filters() {
-			remove_filter('posts_request', array(&$this, 'create_and_unionize_select_statements') );
-			remove_filter('posts_fields', array(&$this, 'add_site_ID_to_posts_fields') );
 
+	function pre_get_posts($query) {
+		if($query->get('multisite')) {
+
+			global $wpdb, $blog_id;
+
+			$this->loop_end = false;
+			$this->blog_id = $blog_id;
+
+			$site_IDs = $wpdb->get_col( "select blog_id from $wpdb->blogs" );
+
+			if ( $query->get('sites__not_in') )
+				foreach($site_IDs as $key => $site_ID )
+					if (in_array($site_ID, $query->get('sites__not_in')) ) unset($site_IDs[$key]);
+
+			if ( $query->get('sites__in') )
+				foreach($site_IDs as $key => $site_ID )
+					if ( ! in_array($site_ID, $query->get('sites__in')) )
+						unset($site_IDs[$key]);
+
+			$site_IDs = array_values($site_IDs);
+
+			$this->sites_to_query = $site_IDs;
+		}
 	}
 
-	function create_and_unionize_select_statements($sql) {
-		global $wpdb;
-
-		$root_site_db_prefix = $wpdb->prefix;
-
-		$page = $this->args['paged'] ? $this->args['paged'] : 1;
-		$posts_per_page = $this->args['posts_per_page'] ? $this->args['posts_per_page'] : 10;
-
-			foreach ($this->sites_to_query as $key => $site_ID) :
-
-			switch_to_blog($site_ID);
-
-			$new_sql_select = str_replace($root_site_db_prefix, $wpdb->prefix, $sql);
-			$new_sql_select = preg_replace("/ LIMIT ([0-9]+), ".$posts_per_page."/", "", $new_sql_select);
-			$new_sql_select = str_replace("SQL_CALC_FOUND_ROWS ", "", $new_sql_select);
-			$new_sql_select = str_replace("# AS site_ID", "'$site_ID' AS site_ID", $new_sql_select);
-			$new_sql_select = preg_replace( '/ORDER BY ([A-Za-z0-9_.]+)/', "", $new_sql_select);
-			$new_sql_select = str_replace(array("DESC", "ASC"), "", $new_sql_select);
-
-			$new_sql_selects[] = $new_sql_select;
-			restore_current_blog();
-
-		endforeach;
-
-		if ( $posts_per_page > 0 ) {
-			$skip = ( $page * $posts_per_page ) - $posts_per_page;
-			$limit = "LIMIT $skip, $posts_per_page";
-		} else {
-            $limit = '';
-        }
-		$orderby = "tables.post_date DESC";
-		$new_sql = "SELECT SQL_CALC_FOUND_ROWS tables.* FROM ( " . implode(" UNION ", $new_sql_selects) . ") tables ORDER BY $orderby " . $limit;
-
-		return $new_sql;
+	function posts_clauses($clauses, $query) {
+		if($query->get('multisite')) {
+			global $wpdb;
+
+			// Start new mysql selection to replace wp_posts on posts_request hook
+			$this->ms_select = array();
+
+			$root_site_db_prefix = $wpdb->prefix;
+			foreach($this->sites_to_query as $site_ID) {
+
+				switch_to_blog($site_ID);
+
+				$ms_select = $clauses['join'] . ' WHERE 1=1 '. $clauses['where'];
+
+				if($clauses['groupby'])
+					$ms_select .= ' GROUP BY ' . $clauses['groupby'];
+
+				$ms_select = str_replace($root_site_db_prefix, $wpdb->prefix, $ms_select);
+				$ms_select = " SELECT $wpdb->posts.*, '$site_ID' as site_ID FROM $wpdb->posts $ms_select ";
+
+				$this->ms_select[] = $ms_select;
+
+				restore_current_blog();
+
+			}
+
+			// Clear join, where and groupby to populate with parsed ms select on posts_request hook;
+			$clauses['join'] = '';
+			$clauses['where'] = '';
+			$clauses['groupby'] = '';
+
+			// Orderby for tables (not wp_posts)
+			$clauses['orderby'] = str_replace($wpdb->posts, 'tables', $clauses['orderby']);
+
+		}
+		return $clauses;
 	}
-
-	function add_site_ID_to_posts_fields($sql) {
-		$sql_statements[] = $sql;
-		$sql_statements[] = "# AS site_ID";
-		return implode(', ', $sql_statements);
+
+	function posts_request($sql, $query) {
+
+		if($query->get('multisite')) {
+
+			global $wpdb;
+
+			// Clean up remanescent WHERE request
+			$sql = str_replace('WHERE 1=1', '', $sql);
+
+			// Multisite request
+			$sql = str_replace("$wpdb->posts.* FROM $wpdb->posts", 'tables.* FROM ( ' . implode(" UNION ", $this->ms_select) . ' ) tables', $sql);
+
+		}
+
+		return $sql;
 	}
-	
-	function switch_to_blog_while_in_loop($post) {
+
+	function the_post($post) {
 		global $blog_id;
-		if($post->site_ID && $blog_id != $post->site_ID )
+
+		if( isset( $this->loop_end ) && !$this->loop_end && $post->site_ID && $blog_id !== $post->site_ID) {
 			switch_to_blog($post->site_ID);
-		else
-			restore_current_blog();
+		}
+
+	}
+
+	function loop_end($query) {
+		global $switched;
+		if($query->get('multisite')) {
+			$this->loop_end = true;
+			if($switched) {
+				switch_to_blog($this->blog_id);
+			}
+		}
 	}
 }
 
+new WP_Query_Multisite();
+
 ?>