From 195292847120349d66e9572a48dfa3e7a5b41f24 Mon Sep 17 00:00:00 2001
From: Yonel Ceruto <yonelceruto@gmail.com>
Date: Tue, 2 Jul 2019 17:48:31 -0400
Subject: [PATCH] Improving the request/response format autodetection

---
 .../Component/HttpFoundation/Request.php      | 23 ++++++++++++++++
 .../Component/HttpFoundation/Response.php     |  2 +-
 .../HttpFoundation/Tests/RequestTest.php      | 26 +++++++++++++++++++
 .../EventListener/DebugHandlersListener.php   |  2 +-
 4 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/src/Symfony/Component/HttpFoundation/Request.php b/src/Symfony/Component/HttpFoundation/Request.php
index 83cdf60169..a950b0a159 100644
--- a/src/Symfony/Component/HttpFoundation/Request.php
+++ b/src/Symfony/Component/HttpFoundation/Request.php
@@ -192,6 +192,10 @@ class Request
 
     protected static $requestFactory;
 
+    /**
+     * @var string|null
+     */
+    private $preferredFormat;
     private $isHostValid = true;
     private $isForwardedValid = true;
 
@@ -1559,6 +1563,25 @@ class Request
         return $this->headers->hasCacheControlDirective('no-cache') || 'no-cache' == $this->headers->get('Pragma');
     }
 
+    public function getPreferredFormat(?string $default = 'html'): ?string
+    {
+        if (null !== $this->preferredFormat) {
+            return $this->preferredFormat;
+        }
+
+        $this->preferredFormat = $this->getRequestFormat($this->getContentType());
+
+        if (null === $this->preferredFormat) {
+            foreach ($this->getAcceptableContentTypes() as $contentType) {
+                if (null !== $this->preferredFormat = $this->getFormat($contentType)) {
+                    break;
+                }
+            }
+        }
+
+        return $this->preferredFormat ?: $default;
+    }
+
     /**
      * Returns the preferred language.
      *
diff --git a/src/Symfony/Component/HttpFoundation/Response.php b/src/Symfony/Component/HttpFoundation/Response.php
index d1263ca7a1..1681558499 100644
--- a/src/Symfony/Component/HttpFoundation/Response.php
+++ b/src/Symfony/Component/HttpFoundation/Response.php
@@ -270,7 +270,7 @@ class Response
         } else {
             // Content-type based on the Request
             if (!$headers->has('Content-Type')) {
-                $format = $request->getRequestFormat();
+                $format = $request->getPreferredFormat();
                 if (null !== $format && $mimeType = $request->getMimeType($format)) {
                     $headers->set('Content-Type', $mimeType);
                 }
diff --git a/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php b/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
index c1168f5e45..6573da0785 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/RequestTest.php
@@ -399,6 +399,32 @@ class RequestTest extends TestCase
         $this->assertEquals('xml', $dup->getRequestFormat());
     }
 
+    public function testGetPreferredFormat()
+    {
+        $request = new Request();
+        $this->assertNull($request->getPreferredFormat(null));
+        $this->assertSame('html', $request->getPreferredFormat());
+        $this->assertSame('json', $request->getPreferredFormat('json'));
+
+        $request->setRequestFormat('atom');
+        $request->headers->set('Content-Type', 'application/json');
+        $request->headers->set('Accept', 'application/xml');
+        $this->assertSame('atom', $request->getPreferredFormat());
+
+        $request = new Request();
+        $request->headers->set('Content-Type', 'application/json');
+        $request->headers->set('Accept', 'application/xml');
+        $this->assertSame('json', $request->getPreferredFormat());
+
+        $request = new Request();
+        $request->headers->set('Accept', 'application/xml');
+        $this->assertSame('xml', $request->getPreferredFormat());
+
+        $request = new Request();
+        $request->headers->set('Accept', 'application/json;q=0.8,application/xml;q=0.9');
+        $this->assertSame('xml', $request->getPreferredFormat());
+    }
+
     /**
      * @dataProvider getFormatToMimeTypeMapProviderWithAdditionalNullFormat
      */
diff --git a/src/Symfony/Component/HttpKernel/EventListener/DebugHandlersListener.php b/src/Symfony/Component/HttpKernel/EventListener/DebugHandlersListener.php
index b0b9a94c28..ebf6c96fcb 100644
--- a/src/Symfony/Component/HttpKernel/EventListener/DebugHandlersListener.php
+++ b/src/Symfony/Component/HttpKernel/EventListener/DebugHandlersListener.php
@@ -174,7 +174,7 @@ class DebugHandlersListener implements EventSubscriberInterface
             $e = $request->attributes->get('exception');
 
             try {
-                return new Response($this->errorFormatter->render($e, $request->getRequestFormat()), $e->getStatusCode(), $e->getHeaders());
+                return new Response($this->errorFormatter->render($e, $request->getPreferredFormat()), $e->getStatusCode(), $e->getHeaders());
             } catch (ErrorRendererNotFoundException $_) {
                 return new Response($this->errorFormatter->render($e), $e->getStatusCode(), $e->getHeaders());
             }