fix `web\Request::getParsedBody()` throws exception for empty body without content-type

framework/web/Request.php

@@ -652,7 +652,7 @@ class Request extends \yii\base\Request implements ServerRequestInterface
         $this->setBody($body);
     }
 
-    private $_parsedBody;
+    private $_parsedBody = false;
 
     /**
      * Returns the request parameters given in the request body.
@@ -663,7 +663,8 @@ class Request extends \yii\base\Request implements ServerRequestInterface
      *
      * Since 2.1.0 body params also include result of [[getUploadedFiles()]].
      *
-     * @return array the request parameters given in the request body.
+     * @return array|null the request parameters given in the request body. A `null` value indicates
+     * the absence of body content.
      * @throws InvalidConfigException if a registered parser does not implement the [[RequestParserInterface]].
      * @throws UnsupportedMediaTypeHttpException if unable to parse raw body.
      * @see getMethod()
@@ -672,7 +673,7 @@ class Request extends \yii\base\Request implements ServerRequestInterface
      */
     public function getParsedBody()
     {
-        if ($this->_parsedBody === null) {
+        if ($this->_parsedBody === false) {
             if (isset($_POST[$this->methodParam])) {
                 $this->_parsedBody = $_POST;
                 unset($this->_parsedBody[$this->methodParam]);
@@ -707,6 +708,8 @@ class Request extends \yii\base\Request implements ServerRequestInterface
                 if ($contentType === 'multipart/form-data') {
                     $this->_parsedBody = ArrayHelper::merge($this->_parsedBody, $this->getUploadedFiles());
                 }
+            } elseif (empty($contentType) && $this->getBody()->getSize() === 0) {
+                $this->_parsedBody = null;
             } else {
                 if ($contentType !== 'application/x-www-form-urlencoded') {
                     throw new UnsupportedMediaTypeHttpException();
@@ -2226,5 +2229,7 @@ class Request extends \yii\base\Request implements ServerRequestInterface
         if (is_object($this->_cookies)) {
             $this->_cookies = clone $this->_cookies;
         }
+
+        $this->_parsedBody = false;
     }
 }

tests/framework/web/RequestTest.php

@@ -662,7 +662,7 @@ class RequestTest extends TestCase
         $_SERVER = $original;
     }
 
-    public function testGetBodyParams()
+    public function testGetParsedBody()
     {
         $body = new MemoryStream();
         $body->write('name=value');
@@ -688,6 +688,23 @@ class RequestTest extends TestCase
     }
 
     /**
+     * @depends testGetParsedBody
+     */
+    public function testParseEmptyBody()
+    {
+        $request = new Request();
+        $request->setMethod('GET');
+        $request->setBody(new MemoryStream());
+
+        $this->assertNull($request->getParsedBody());
+
+        try {
+            $request->withHeader('Content-Type', 'test/json')->getParsedBody();
+        } catch (UnsupportedMediaTypeHttpException $noContentException) {}
+        $this->assertTrue(isset($noContentException));
+    }
+
+    /**
      * Data provider for [[testDefaultUploadedFiles()]]
      * @return array test data.
      */
@@ -810,7 +827,7 @@ class RequestTest extends TestCase
     }
 
     /**
-     * @depends testGetBodyParams
+     * @depends testGetParsedBody
      * @dataProvider dataProviderDefaultUploadedFiles
      *
      * @param array $rawFiles