Add Reverse Nested aggregation.

changes.txt

@@ -1,10 +1,12 @@
 CHANGES
 
+2014-06-30
+- Add Reverse Nested aggregation (http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/search-aggregations-bucket-reverse-nested-aggregation.html).
 
 2014-06-14
 - Release v1.2.1.0
 - Removed the requirement to set arguments filter and/or query in Filtered, according to the documentation: http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/query-dsl-filtered-query.html #616
- 
+
 2014-06-13
 - Stop ClientTest->testDeleteIdsIdxStringTypeString from failing 1/3 of the time #634
 - Stop ScanAndScrollTest->testQuerySizeOverride from failing frequently for no reason #635

lib/Elastica/Aggregation/ReverseNested.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace Elastica\Aggregation;
+
+/**
+ * Reversed Nested Aggregation
+ *
+ * @package Elastica\Aggregation
+ * @link http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/search-aggregations-bucket-reverse-nested-aggregation.html
+ */
+class ReverseNested extends AbstractAggregation
+{
+    /**
+     * @param string $name The name of this aggregation
+     * @param string $path Optional path to the nested object for this aggregation. Defaults to the root of the main document.
+     */
+    public function __construct($name, $path = null)
+    {
+        parent::__construct($name);
+
+        if ($path !== null) {
+            $this->setPath($path);
+        }
+    }
+
+    /**
+     * Set the nested path for this aggregation
+     *
+     * @param string $path
+     * @return ReverseNested
+     */
+    public function setPath($path)
+    {
+        return $this->setParam("path", $path);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function toArray()
+    {
+        $array = parent::toArray();
+
+        // ensure we have an object for the reverse_nested key.
+        // if we don't have a path, then this would otherwise get encoded as an empty array, which is invalid.
+        $array['reverse_nested'] = (object)$array['reverse_nested'];
+
+        return $array;
+    }
+}

test/lib/Elastica/Test/Aggregation/ReverseNestedTest.php

@@ -0,0 +1,124 @@
+<?php
+
+namespace Elastica\Test\Aggregation;
+
+use Elastica\Aggregation\Terms;
+use Elastica\Aggregation\Nested;
+use Elastica\Aggregation\ReverseNested;
+use Elastica\Document;
+use Elastica\Query;
+use Elastica\Type\Mapping;
+
+class ReverseNestedTest extends BaseAggregationTest
+{
+    protected function setUp()
+    {
+        parent::setUp();
+        $this->_index = $this->_createIndex("nested");
+        $mapping = new Mapping();
+        $mapping->setProperties(array(
+            "comments" => array(
+                "type" => "nested",
+                "properties" => array(
+                    "name" => array("type" => "string"),
+                    "body" => array("type" => "string")
+                )
+            )
+        ));
+        $type = $this->_index->getType("test");
+        $type->setMapping($mapping);
+        $docs = array(
+            new Document("1", array(
+                "comments" => array(
+                    array(
+                        "name" => "bob",
+                        "body" => "this is bobs comment",
+                    ),
+                    array(
+                        "name" => "john",
+                        "body" => "this is johns comment",
+                    ),
+                ),
+                "tags" => array("foo", "bar"),
+            )),
+            new Document("2", array(
+                 "comments" => array(
+                    array(
+                        "name" => "bob",
+                        "body" => "this is another comment from bob",
+                    ),
+                    array(
+                        "name" => "susan",
+                        "body" => "this is susans comment",
+                    ),
+                ),
+                "tags" => array("foo", "baz"),
+            ))
+        );
+        $type->addDocuments($docs);
+        $this->_index->refresh();
+    }
+
+    public function testPathNotSetIfNull()
+    {
+        $agg = new ReverseNested('nested');
+        $this->assertFalse($agg->hasParam('path'));
+    }
+
+    public function testPathSetIfNotNull()
+    {
+        $agg = new ReverseNested('nested', 'some_field');
+        $this->assertEquals('some_field', $agg->getParam('path'));
+    }
+
+    public function testReverseNestedAggregation()
+    {
+        $agg = new Nested("comments", "comments");
+        $names = new Terms("name");
+        $names->setField("comments.name");
+
+        $tags = new Terms("tags");
+        $tags->setField("tags");
+
+        $reverseNested = new ReverseNested("main");
+        $reverseNested->addAggregation($tags);
+
+        $names->addAggregation($reverseNested);
+
+        $agg->addAggregation($names);
+
+        $query = new Query();
+        $query->addAggregation($agg);
+        $results = $this->_index->search($query)->getAggregation("comments");
+
+        $this->assertArrayHasKey('name', $results);
+        $nameResults = $results['name'];
+
+        $this->assertCount(3, $nameResults['buckets']);
+
+        // bob
+        $this->assertEquals('bob', $nameResults['buckets'][0]['key']);
+        $tags = array(
+            array('key' => 'foo', 'doc_count' => 2),
+            array('key' => 'bar', 'doc_count' => 1),
+            array('key' => 'baz', 'doc_count' => 1),
+        );
+        $this->assertEquals($tags, $nameResults['buckets'][0]['main']['tags']['buckets']);
+
+        // john
+        $this->assertEquals('john', $nameResults['buckets'][1]['key']);
+        $tags = array(
+            array('key' => 'bar', 'doc_count' => 1),
+            array('key' => 'foo', 'doc_count' => 1),
+        );
+        $this->assertEquals($tags, $nameResults['buckets'][1]['main']['tags']['buckets']);
+
+        // susan
+        $this->assertEquals('susan', $nameResults['buckets'][2]['key']);
+        $tags = array(
+            array('key' => 'baz', 'doc_count' => 1),
+            array('key' => 'foo', 'doc_count' => 1),
+        );
+        $this->assertEquals($tags, $nameResults['buckets'][2]['main']['tags']['buckets']);
+    }
+}