Allow empty aggregation

Author: erichard

src/Aggregation/AbstractAggregation.php

@@ -14,7 +14,7 @@ abstract class AbstractAggregation implements BuildsArray
      */
     public function __construct(
         private string $name,
-        array $aggregations = []
+        array $aggregations = [],
     ) {
         $this->aggregations = $aggregations;
     }
@@ -24,8 +24,14 @@ public function __construct(
      */
     public function build(): array
     {
+        $build = $this->buildAggregation();
+
+        if ([] === $build) {
+            $build = new \stdClass();
+        }
+
         $data = [
-            $this->getType() => $this->buildAggregation(),
+            $this->getType() => $build,
         ];
 
         $this->buildAggregationsTo($data);

src/Aggregation/Aggregation.php

@@ -15,7 +15,7 @@ class Aggregation
     public static function terms(
         string $name,
         string|Field|InlineScript $fieldOrSource,
-        array $aggregations = []
+        array $aggregations = [],
     ): TermsAggregation {
         return new TermsAggregation($name, $fieldOrSource, $aggregations);
     }
@@ -27,7 +27,7 @@ public static function dateHistogram(
         string $nameAndField,
         string $calendarInterval,
         ?string $field = null,
-        array $aggregations = []
+        array $aggregations = [],
     ): DateHistogramAggregation {
         return new DateHistogramAggregation($nameAndField, $calendarInterval, $field, $aggregations);
     }
@@ -43,7 +43,7 @@ public static function nested(string $name, string $path, array $aggregations =
     /**
      * @param array<AbstractAggregation> $aggregations
      */
-    public static function reverseNested(string $name, string $path, array $aggregations = []): ReverseNestedAggregation
+    public static function reverseNested(string $name, ?string $path = null, array $aggregations = []): ReverseNestedAggregation
     {
         return new ReverseNestedAggregation($name, $path, $aggregations);
     }
@@ -62,7 +62,7 @@ public static function filter(string $name, QueryInterface $query, array $aggreg
     public static function cardinality(
         string $nameAndField,
         string|SourceScript|Field|null $fieldOrSource = null,
-        array $aggregations = []
+        array $aggregations = [],
     ): CardinalityAggregation {
         return new CardinalityAggregation($nameAndField, $fieldOrSource, $aggregations);
     }
@@ -73,7 +73,7 @@ public static function cardinality(
     public static function max(
         string $nameAndField,
         string|SourceScript|Field|null $fieldOrSource = null,
-        array $aggregations = []
+        array $aggregations = [],
     ): MaxAggregation {
         return new MaxAggregation($nameAndField, $fieldOrSource, $aggregations);
     }
@@ -84,7 +84,7 @@ public static function max(
     public static function min(
         string $nameAndField,
         string|SourceScript|Field|null $fieldOrSource = null,
-        array $aggregations = []
+        array $aggregations = [],
     ): MinAggregation {
         return new MinAggregation($nameAndField, $fieldOrSource, $aggregations);
     }
@@ -95,7 +95,7 @@ public static function min(
     public static function sum(
         string $nameAndField,
         string|SourceScript|Field|null $fieldOrSource = null,
-        array $aggregations = []
+        array $aggregations = [],
     ): SumAggregation {
         return new SumAggregation($nameAndField, $fieldOrSource, $aggregations);
     }

src/Aggregation/NestedAggregation.php

@@ -9,8 +9,8 @@ class NestedAggregation extends AbstractAggregation
      */
     public function __construct(
         string $name,
-        private string $path,
-        array $aggregations = []
+        private ?string $path = null,
+        array $aggregations = [],
     ) {
         parent::__construct($name, $aggregations);
     }
@@ -34,6 +34,10 @@ protected function getType(): string
 
     protected function buildAggregation(): array
     {
+        if (null === $this->path) {
+            return [];
+        }
+
         return [
             'path' => $this->path,
         ];