[10.x] Add whenAggregated method to ConditionallyLoadsAttributes trait (#47417)

* Added `whenAveraged`

* Update ConditionallyLoadsAttributes.php

* Added whenAggregated

* Added tests

---------

Co-authored-by: Taylor Otwell <[email protected]>

Author: akr4m

src/Illuminate/Http/Resources/ConditionallyLoadsAttributes.php

@@ -300,6 +300,35 @@ public function whenCounted($relationship, $value = null, $default = null)
         return value($value, $this->resource->{$attribute});
     }
 
+    /**
+     * Retrieve a relationship aggregated value if it exists.
+     *
+     * @param  string  $relationship
+     * @param  string  $column
+     * @param  string  $aggregate
+     * @param  mixed  $value
+     * @param  mixed  $default
+     * @return \Illuminate\Http\Resources\MissingValue|mixed
+     */
+    public function whenAggregated($relationship, $column, $aggregate, $value = null, $default = null)
+    {
+        $attribute = (string) Str::of($relationship)->snake()->append('_')->append($aggregate)->append('_')->finish($column);
+
+        if (! isset($this->resource->getAttributes()[$attribute])) {
+            return value($default);
+        }
+
+        if (func_num_args() === 3) {
+            return $this->resource->{$attribute};
+        }
+
+        if ($this->resource->{$attribute} === null) {
+            return;
+        }
+
+        return value($value, $this->resource->{$attribute});
+    }
+
     /**
      * Execute a callback if the given pivot table has been loaded.
      *

tests/Integration/Http/Fixtures/PostResourceWithOptionalRelationshipAggregates.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace Illuminate\Tests\Integration\Http\Fixtures;
+
+class PostResourceWithOptionalRelationshipAggregates extends PostResource
+{
+    public function toArray($request)
+    {
+        return [
+            'id' => $this->id,
+            'title' => $this->title,
+            'average_rating' => $this->whenAggregated('comments', 'rating', 'avg'),
+            'minimum_rating' => $this->whenAggregated('comments', 'rating', 'min'),
+            'maximum_rating' => $this->whenAggregated('comments', 'rating', 'max', fn ($avg) => "$avg ratings", 'Default Value'),
+        ];
+    }
+}

tests/Integration/Http/ResourceTest.php

@@ -35,6 +35,7 @@
 use Illuminate\Tests\Integration\Http\Fixtures\PostResourceWithOptionalMerging;
 use Illuminate\Tests\Integration\Http\Fixtures\PostResourceWithOptionalPivotRelationship;
 use Illuminate\Tests\Integration\Http\Fixtures\PostResourceWithOptionalRelationship;
+use Illuminate\Tests\Integration\Http\Fixtures\PostResourceWithOptionalRelationshipAggregates;
 use Illuminate\Tests\Integration\Http\Fixtures\PostResourceWithOptionalRelationshipCounts;
 use Illuminate\Tests\Integration\Http\Fixtures\PostResourceWithoutWrap;
 use Illuminate\Tests\Integration\Http\Fixtures\PostResourceWithUnlessOptionalData;
@@ -449,6 +450,65 @@ public function testResourcesMayLoadOptionalRelationships()
         ]);
     }
 
+    public function testResourcesMayLoadOptionalRelationshipAggregates()
+    {
+        Route::get('/', function () {
+            $post = new Post([
+                'id' => 5,
+                'title' => 'Test Title',
+                'comments_avg_rating' => 3.8,
+                'comments_min_rating' => 2,
+                'comments_max_rating' => 5
+            ]);
+
+            return new PostResourceWithOptionalRelationshipAggregates($post);
+        });
+
+        $response = $this->withoutExceptionHandling()->get(
+            '/', ['Accept' => 'application/json']
+        );
+
+        $response->assertStatus(200);
+
+        $response->assertExactJson([
+            'data' => [
+                'id' => 5,
+                'title' => 'Test Title',
+                'average_rating' => 3.8,
+                'minimum_rating' => 2,
+                'maximum_rating' => "5 ratings",
+            ],
+        ]);
+    }
+
+    public function testResourcesMayHaveOptionalRelationshipAggregates()
+    {
+        Route::get('/', function () {
+            $post = new Post([
+                'id' => 5,
+                'title' => 'Test Title',
+            ]);
+
+            return new PostResourceWithOptionalRelationshipAggregates($post);
+        });
+
+        $response = $this->withoutExceptionHandling()->get(
+            '/', ['Accept' => 'application/json']
+        );
+
+        $response->assertStatus(200);
+
+        $response->assertExactJson([
+            'data' => [
+                'id' => 5,
+                'title' => 'Test Title',
+                'average_rating' => null,
+                'minimum_rating' => null,
+                'maximum_rating' => "Default Value",
+            ],
+        ]);
+    }
+
     public function testResourcesMayShowsNullForLoadedRelationshipWithValueNull()
     {
         Route::get('/', function () {