Fix etags

Author: emteknetnz

README.md

@@ -52,13 +52,13 @@ This assumes that you have an existing project created with `silverstripe/cms` i
 ```php
 <?php
 
-use emteknetnz\RestApi\RestApiEndpoint;
+use emteknetnz\RestApi\Controllers\RestApiEndpoint;
 use SilverStripe\CMS\Model\SiteTree;
 
 class MySiteTreeEndpoint extends RestApiEndpoint
 {
     private static array $api_config = [
-        RestApiEndpoint::PATH = 'api/pages';
+        RestApiEndpoint::PATH => 'api/pages',
         RestApiEndpoint::DATA_CLASS => SiteTree::class,
         RestApiEndpoint::ACCESS => RestApiEndpoint::PUBLIC,
         RestApiEndpoint::FIELDS => [
@@ -69,6 +69,7 @@ class MySiteTreeEndpoint extends RestApiEndpoint
         ],
     ];
 }
+
 ```
 
 Run `https://mysite.test/dev/build?flush=1`

src/Controllers/RestApiEndpoint.php

@@ -260,6 +260,7 @@ private function apiOptions(): HTTPResponse
         $response = $this->getResponse();
         $response->setStatusCode(204);
         $response->addHeader('Allow', $this->allowedOptions());
+        $response->setBody('');
         return $response;
     }
 
@@ -953,7 +954,7 @@ private function jsonResponse(array $data, int $code = 200, array $headers = [])
             // https://www.rfc-editor.org/rfc/rfc7232#section-2.3
             $etag = $response->getHeader('ETag');
             if (!$etag) {
-                $etag = sprintf('"%s"', md5($response->getBody() ?? ''));
+                $etag = sprintf('"%s"', md5($body));
                 $response->addHeader('ETag', $etag);
             }
         }

tests/Controllers/RestApiEndpointTest.php

@@ -2228,14 +2228,17 @@ public function testETag()
     {
         $this->setConfig(self::CALL_CAN_METHODS, self::NONE);
         // double quotes inside single quotes are intentional
-        $expected = '"d41d8cd98f00b204e9800998ecf8427e"';
+        $expectedViewOperation = '"6cd52dbfaf406fcece186c5a9004e677"';
+        $expectedBlankBody = '"d41d8cd98f00b204e9800998ecf8427e"';
         $taskID = TestTask::get()->first()->ID;
-        $this->assertSame($expected, $this->req('GET', $taskID)->getHeader('ETag'));
-        $this->assertSame($expected, $this->req('HEAD', $taskID)->getHeader('ETag'));
+        $this->assertSame($expectedViewOperation, $this->req('GET', $taskID)->getHeader('ETag'));
+        $this->assertSame($expectedViewOperation, $this->req('HEAD', $taskID)->getHeader('ETag'));
         $this->assertSame(null, $this->req('POST')->getHeader('ETag'));
         $this->assertSame(null, $this->req('PATCH', $taskID, null, null, ['title' => 'changed'])->getHeader('ETag'));
         $this->assertSame(null, $this->req('DELETE', $taskID)->getHeader('ETag'));
-        $this->assertSame(null, $this->req('OPTIONS')->getHeader('ETag'));
+        $this->assertSame(null, $this->req('PUT')->getHeader('ETag'));
+        // OPTIONS gets an etag added by ChangeDetectionMiddleware
+        $this->assertSame($expectedBlankBody, $this->req('OPTIONS')->getHeader('ETag'));
     }
 
     public function testExtensionHooks(): void