Merge pull request #26 from webbaard/feature/IB-1280-sum-aggregation

IB-1280 added sum aggregation

README.md

@@ -206,6 +206,14 @@ The following query types are available:
 \Spatie\ElasticsearchQueryBuilder\Aggregations\MinAggregation::create('min_price', 'price');
 ```
 
+#### `SumAggregation`
+
+[https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-metrics-sum-aggregation.html](https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-metrics-sum-aggregation.html)
+
+```php
+\Spatie\ElasticsearchQueryBuilder\Aggregations\SumAggregation::create('sum_price', 'price');
+```
+
 #### `NestedAggregation`
 
 [https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-nested-aggregation.html](https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-nested-aggregation.html)

src/Aggregations/SumAggregation.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace Spatie\ElasticsearchQueryBuilder\Aggregations;
+
+use Spatie\ElasticsearchQueryBuilder\Aggregations\Concerns\WithMissing;
+
+class SumAggregation extends Aggregation
+{
+    use WithMissing;
+
+    protected string $field;
+
+    public static function create(string $name, string $field): self
+    {
+        return new self($name, $field);
+    }
+
+    public function __construct(string $name, string $field)
+    {
+        $this->name = $name;
+        $this->field = $field;
+    }
+
+    public function payload(): array
+    {
+        $parameters = [
+            'field' => $this->field,
+        ];
+
+        if ($this->missing) {
+            $parameters['missing'] = $this->missing;
+        }
+
+        return [
+            'sum' => $parameters,
+        ];
+    }
+}