add ChildrenAggregation

Aggregation/ChildrenAggregation.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\ElasticsearchBundle\DSL\Aggregation;
+
+use ONGR\ElasticsearchBundle\DSL\Aggregation\Type\BucketingTrait;
+
+/**
+ * Class representing ChildrenAggregation.
+ */
+class ChildrenAggregation extends AbstractAggregation
+{
+    use BucketingTrait;
+
+    /**
+     * @var string
+     */
+    private $children;
+
+    /**
+     * Return children.
+     *
+     * @return string
+     */
+    public function getChildren()
+    {
+        return $this->children;
+    }
+
+    /**
+     * Sets children.
+     *
+     * @param string $children
+     */
+    public function setChildren($children)
+    {
+        $this->children = $children;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getType()
+    {
+        return 'children';
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getArray()
+    {
+        if (count($this->getAggregations()) == 0) {
+            throw new \LogicException("Children aggregation `{$this->getName()}` has no aggregations added");
+        }
+
+        return ['type' => $this->getChildren()];
+    }
+}