Merge pull request #109 from einorler/geo_centroid_agg

added geo centroid aggregation

docs/Aggregation/GeoCentroid.md

+# Geo Centroid Aggregation
+
+> More info about histogram aggregation is in the [official elasticsearch docs][1]
+
+A metric aggregation that computes the weighted centroid from all coordinate values for a Geo-point datatype field.
+The data type of the field that is specified for the aggregation must be `geo-point`.
+
+## Simple example
+
+```JSON
+{
+    "query" : {
+        "match" : { "crime" : "burglary" }
+    },
+    "aggs" : {
+        "centroid" : {
+            "geo_centroid" : {
+                "field" : "location"
+            }
+        }
+    }
+}
+```
+
+And now the query via DSL:
+
+```php
+$geoCentroidAggregation = new GeoCentroidAggregation('centroid', 'location');
+
+$search = new Search();
+$search->addQuery(new MatchQuery('crime', 'burglary'));
+$search->addAggregation($geoCentroidAggregation);
+
+$queryArray = $search->toArray();
+```
+
+## Advanced example
+
+The query provides more information when when combined as a sub-aggregation to other bucket aggregations. Here is an example of that:
+
+```JSON
+
+{
+    "query" : {
+        "match" : { "crime" : "burglary" }
+    },
+    "aggs" : {
+        "towns" : {
+            "terms" : { "field" : "town" },
+            "aggs" : {
+                "centroid" : {
+                    "geo_centroid" : { "field" : "location" }
+                }
+            }
+        }
+    }
+}
+
+```
+And now via DSL:
+
+```php
+$geoCentroidAggregation = new GeoCentroidAggregation('centroid', 'location');
+$termsAggregation = new TermsAggregation('towns', 'town');
+$termsAggregation->addAggregation($geoCentroidAggregation);
+
+$search = new Search();
+$search->addQuery(new MatchQuery('crime', 'burglary'));
+$search->addAggregation($termsAggregation);
+
+$queryArray = $search->toArray();
+```
+
+[1]: https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-metrics-geocentroid-aggregation.html

src/Aggregation/GeoCentroidAggregation.php

+<?php
+
+/*
+ * This file is part of the ONGR package.
+ *
+ * (c) NFQ Technologies UAB <info@nfq.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace ONGR\ElasticsearchDSL\Aggregation;
+
+use ONGR\ElasticsearchDSL\Aggregation\Type\MetricTrait;
+
+/**
+ * Class representing geo centroid aggregation.
+ *
+ * @link https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-metrics-geocentroid-aggregation.html
+ */
+class GeoCentroidAggregation extends AbstractAggregation
+{
+    use MetricTrait;
+
+    /**
+     * Inner aggregations container init.
+     *
+     * @param string $name
+     * @param string $field
+     */
+    public function __construct($name, $field = null)
+    {
+        parent::__construct($name);
+
+        $this->setField($field);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getArray()
+    {
+        $data = [];
+        if ($this->getField()) {
+            $data['field'] = $this->getField();
+        } else {
+            throw new \LogicException('Geo centroid aggregation must have a field set.');
+        }
+
+        return $data;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getType()
+    {
+        return 'geo_centroid';
+    }
+}

tests/Aggregation/GeoCentroidAggregationTest.php

+<?php
+
+/*
+ * This file is part of the ONGR package.
+ *
+ * (c) NFQ Technologies UAB <info@nfq.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace ONGR\ElasticsearchDSL\Tests\Aggregation;
+
+use ONGR\ElasticsearchDSL\Aggregation\GeoCentroidAggregation;
+
+/**
+ * Unit test for children aggregation.
+ */
+class GeoCentroidAggregationTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Test if exception is thrown when field is not provided
+     *
+     * @expectedException \LogicException
+     */
+    public function testGetArrayException()
+    {
+        $aggregation = new GeoCentroidAggregation('foo');
+        $aggregation->getArray();
+    }
+
+    /**
+     * Tests getType method.
+     */
+    public function testGeoCentroidAggregationGetType()
+    {
+        $aggregation = new GeoCentroidAggregation('foo');
+        $this->assertEquals('geo_centroid', $aggregation->getType());
+    }
+
+    /**
+     * Tests getArray method.
+     */
+    public function testGeoCentroidAggregationGetArray()
+    {
+        $aggregation = new GeoCentroidAggregation('foo', 'location');
+        $this->assertEquals(['field' => 'location'], $aggregation->getArray());
+    }
+}