Add an extension hook to allow altering search results

code/solr/SolrIndex.php

@@ -795,7 +795,13 @@ abstract class SolrIndex extends SearchIndex
             }
         }
 
-        return new ArrayData($ret);
+        $ret = new ArrayData($ret);
+
+        // Enable extensions to add extra data from the response into
+        // the returned results set.
+        $this->extend('updateSearchResults', $ret, $res);
+
+        return $ret;
     }
 
 

docs/en/Solr.md

@@ -335,6 +335,50 @@ The searched term is highlighted with an `<em>` tag by default.
 Note: It is recommended to strip out all HTML tags and convert entities on the indexed content,
 to avoid matching HTML attributes, and cluttering highlighted content with unparsed HTML.
 
+### Adding additional information into search results
+
+Inside the SolrIndex::search() function, the third-party library solr-php-client
+is used to send data to Solr and parse the response.  Additional information can
+be pulled from this response and added to your results object for use in templates
+using the `updateSearchResults()` extension hook.
+
+	$index = new MyIndex();
+	$query = new SearchQuery();
+	$query->search('My Term');
+	$results = $index->search($query, -1, -1, array(
+		'facet' => 'true',
+		'facet.field' => 'SiteTree_ClassName',
+	));
+
+By adding facet fields into the query parameters, our response object from Solr
+now contains some additional information that we can add into the results sent
+to the page.
+
+	<?php
+	class MyResultsExtension extends Extension {
+		/**
+		 * Adds extra information from the solr-php-client repsonse
+		 * into our search results.
+		 * @param $results The ArrayData that will be used to generate search
+		 *        results pages.
+		 * @param $response The solr-php-client response object.
+		 */
+		function updateSearchResults($results, $response) {
+			$facetCounts = array();
+			if (isset($response->facet_counts)) {
+				foreach ($response->facet_counts as $facet => $count) {
+					$facetCounts[] = new ArrayData(array(
+						'Name' => $facet,
+						'Count' => $count,
+					));
+				}
+			}
+			$results->setField('FacetCounts', new ArrayList($facetCounts));
+		}
+	}
+
+We can now access the facet information inside our templates.
+
 ### Adding Analyzers, Tokenizers and Token Filters
 
 When a document is indexed, its individual fields are subject to the analyzing and tokenizing filters that can transform and normalize the data in the fields. For example — removing blank spaces, removing html code, stemming, removing a particular character and replacing it with another