From 8dcb2f2a0845028746d83a47c845200eb26099bd Mon Sep 17 00:00:00 2001
From: Choraimy Kroonstuiver <3661474+axlon@users.noreply.github.com>
Date: Tue, 15 Aug 2023 14:55:52 +0200
Subject: [PATCH] Allow default values when merging values into a resource

---
 .../ConditionallyLoadsAttributes.php          | 16 +++++++++----
 tests/Integration/Http/ResourceTest.php       | 23 +++++++++++++++++++
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/src/Illuminate/Http/Resources/ConditionallyLoadsAttributes.php b/src/Illuminate/Http/Resources/ConditionallyLoadsAttributes.php
index dfcc202229fd..3f25ca052407 100644
--- a/src/Illuminate/Http/Resources/ConditionallyLoadsAttributes.php
+++ b/src/Illuminate/Http/Resources/ConditionallyLoadsAttributes.php
@@ -140,11 +140,16 @@ protected function merge($value)
      *
      * @param  bool  $condition
      * @param  mixed  $value
+     * @param  mixed  $default
      * @return \Illuminate\Http\Resources\MergeValue|mixed
      */
-    protected function mergeWhen($condition, $value)
+    protected function mergeWhen($condition, $value, $default = null)
     {
-        return $condition ? new MergeValue(value($value)) : new MissingValue;
+        if ($condition) {
+            return new MergeValue(value($value));
+        }
+
+        return func_num_args() === 3 ? new MergeValue(value($default)) : new MissingValue();
     }
 
     /**
@@ -152,11 +157,14 @@ protected function mergeWhen($condition, $value)
      *
      * @param  bool  $condition
      * @param  mixed  $value
+     * @param  mixed  $default
      * @return \Illuminate\Http\Resources\MergeValue|mixed
      */
-    protected function mergeUnless($condition, $value)
+    protected function mergeUnless($condition, $value, $default = null)
     {
-        return ! $condition ? new MergeValue(value($value)) : new MissingValue;
+        $arguments = func_num_args() === 2 ? [$value] : [$value, $default];
+
+        return $this->mergeWhen(! $condition, ...$arguments);
     }
 
     /**
diff --git a/tests/Integration/Http/ResourceTest.php b/tests/Integration/Http/ResourceTest.php
index 9e8ee81f5841..d4217efecddc 100644
--- a/tests/Integration/Http/ResourceTest.php
+++ b/tests/Integration/Http/ResourceTest.php
@@ -1598,6 +1598,29 @@ public function work()
         ], $results);
     }
 
+    public function testMergeValuesMayFallbackToDefaults()
+    {
+        $filter = new class
+        {
+            use ConditionallyLoadsAttributes;
+
+            public function work()
+            {
+                return $this->filter([
+                    $this->mergeUnless(false, ['Taylor', 'Mohamed'], ['First', 'Second']),
+                    $this->mergeWhen(false, ['Adam', 'Matt'], ['Abigail', 'Lydia']),
+                    'Jeffrey',
+                ]);
+            }
+        };
+
+        $results = $filter->work();
+
+        $this->assertEquals([
+            'Taylor', 'Mohamed', 'Abigail', 'Lydia', 'Jeffrey',
+        ], $results);
+    }
+
     public function testNestedMerges()
     {
         $filter = new class