fix: prevent casting empty string to array from triggering json error (#52415)

Author: calebdw

src/Illuminate/Database/Eloquent/Concerns/HasAttributes.php

@@ -1271,7 +1271,11 @@ protected function asJson($value)
      */
     public function fromJson($value, $asObject = false)
     {
-        return Json::decode($value ?? '', ! $asObject);
+        if ($value === null || $value === '') {
+            return null;
+        }
+
+        return Json::decode($value, ! $asObject);
     }
 
     /**

tests/Database/DatabaseConcernsHasAttributesTest.php

@@ -21,6 +21,14 @@ public function testWithConstructorArguments()
         $attributes = $instance->getMutatedAttributes();
         $this->assertEquals(['some_attribute'], $attributes);
     }
+
+    public function testCastingEmptyStringToArrayDoesNotError()
+    {
+        $instance = new HasAttributesWithArrayCast();
+        $this->assertEquals(['foo' => null], $instance->attributesToArray());
+
+        $this->assertTrue(json_last_error() === JSON_ERROR_NONE);
+    }
 }
 
 class HasAttributesWithoutConstructor
@@ -40,3 +48,23 @@ public function __construct($someValue)
     {
     }
 }
+
+class HasAttributesWithArrayCast
+{
+    use HasAttributes;
+
+    public function getArrayableAttributes(): array
+    {
+        return ['foo' => ''];
+    }
+
+    public function getCasts(): array
+    {
+        return ['foo' => 'array'];
+    }
+
+    public function usesTimestamps(): bool
+    {
+        return false;
+    }
+}