Fix usage of class public properties object in structure

Author: alexander-schranz

src/Symfony/Component/HttpFoundation/StreamedJsonResponse.php

@@ -74,11 +74,11 @@ private function stream(): void
             if (self::PLACEHOLDER === $key) {
                 // if the placeholder is already in the structure it should be replaced with a new one that explode
                 // works like expected for the structure
-                $generators[] = $item;
+                $generators[] = $key;
             }
 
-            // generators should be used but for better DX all kind of Traversable are supported
-            if ($item instanceof \Traversable || $item instanceof \JsonSerializable) {
+            // generators should be used but for better DX all kind of Traversable and objects are supported
+            if (is_object($item)) {
                 $generators[] = $item;
                 $item = self::PLACEHOLDER;
             } elseif (self::PLACEHOLDER === $item) {
@@ -97,7 +97,7 @@ private function stream(): void
             // send first and between parts of the structure
             echo $jsonParts[$index];
 
-            if (self::PLACEHOLDER === $generator || $generator instanceof \JsonSerializable) {
+            if ($generator instanceof \JsonSerializable || !$generator instanceof \Traversable) {
                 // the placeholders and JsonSerializable items in the structure are rendered here
                 echo json_encode($generator, $jsonEncodingOptions);
 
@@ -106,6 +106,7 @@ private function stream(): void
 
             $isFirstItem = true;
             $startTag = '[';
+
             foreach ($generator as $key => $item) {
                 if ($isFirstItem) {
                     $isFirstItem = false;

src/Symfony/Component/HttpFoundation/Tests/StreamedJsonResponseTest.php

@@ -155,6 +155,25 @@ public function testResponseStatusCode()
         $this->assertSame(201, $response->getStatusCode());
     }
 
+    public function testPlaceholderAsObjectStructure()
+    {
+        $object = new class() {
+            public $__symfony_json__ = 'foo';
+            public $bar = '__symfony_json__';
+        };
+
+        $content = $this->createSendResponse(
+            [
+                'object' => $object,
+                // add a Generator to make sure it still work in combination with other object holding placeholders
+                'articles' => $this->generatorArray('Article'),
+            ],
+        );
+
+        $this->assertSame('{"object":{"__symfony_json__":"foo","bar":"__symfony_json__"},"articles":[{"title":"Article 1"},{"title":"Article 2"},{"title":"Article 3"}]}', $content);
+    }
+
+
     public function testResponseHeaders()
     {
         $response = new StreamedJsonResponse([], 200, ['X-Test' => 'Test']);