RedirectorPageController: Add extension hook to customise the HTTPRes…

…ponse for empty links

code/Model/RedirectorPageController.php

@@ -24,7 +24,12 @@ public function index(HTTPRequest $request)
         if (!$this->getResponse()->isFinished() && $link = $page->redirectionLink()) {
             $this->redirect($link, 301);
         }
-        return parent::handleAction($request, 'handleIndex');
+
+        $response = parent::handleAction($request, 'handleIndex');
+
+        $this->extend('onMissingLinkResponse', $response);
+
+        return $response;
     }
 
     /**

tests/php/Model/RedirectorPageTest.php

@@ -39,6 +39,8 @@ public function testEmptyRedirectors()
         /* If a redirector page is misconfigured, then its link method will just return the usual URLSegment-generated value */
         $page1 = $this->objFromFixture(RedirectorPage::class, 'badexternal');
         $this->assertEquals('/bad-external/', $page1->Link());
+        $response = $this->get($page1->Link());
+        $this->assertEquals(200, $response->getStatusCode());
 
         /* An error message will be shown if you visit it */
         $content = $this->get(Director::makeRelative($page1->Link()))->getBody();
@@ -49,6 +51,33 @@ public function testEmptyRedirectors()
         $this->assertEquals('/bad-internal/', $page2->Link());
         $content = $this->get(Director::makeRelative($page2->Link()))->getBody();
         $this->assertContains('message-setupWithoutRedirect', $content);
+        $response = $this->get($page2->Link());
+        $this->assertEquals(200, $response->getStatusCode());
+    }
+
+    public function testOnMissingLinkResponse()
+    {
+        /* And extension hook is configured to provide a custom behaviour for handling empty links */
+        RedirectorPageController::add_extension(RedirectorPageTest_MissingLinkExtension::class);
+
+        $page1 = $this->objFromFixture(RedirectorPage::class, 'badexternal');
+        $this->assertEquals('/bad-external/', $page1->Link());
+        $response = $this->get($page1->Link());
+        $this->assertEquals(404, $response->getStatusCode());
+
+        /* An error message will be shown if you visit it */
+        $content = $this->get(Director::makeRelative($page1->Link()))->getBody();
+        $this->assertContains('message-setupWithoutRedirect', $content);
+
+        /* This also applies for internal links */
+        $page2 = $this->objFromFixture(RedirectorPage::class, 'badinternal');
+        $this->assertEquals('/bad-internal/', $page2->Link());
+        $content = $this->get(Director::makeRelative($page2->Link()))->getBody();
+        $this->assertContains('message-setupWithoutRedirect', $content);
+        $response = $this->get($page2->Link());
+        $this->assertEquals(404, $response->getStatusCode());
+
+        RedirectorPageController::remove_extension(RedirectorPageTest_MissingLinkExtension::class);
     }
 
     public function testReflexiveAndTransitiveInternalRedirectors()

tests/php/Model/RedirectorPageTest_MissingLinkExtension.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace SilverStripe\CMS\Tests\Model;
+
+use SilverStripe\Control\HTTPResponse;
+use SilverStripe\Core\Extension;
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\ORM\FieldType\DBHTMLText;
+
+class RedirectorPageTest_MissingLinkExtension extends Extension implements TestOnly
+{
+
+    /**
+     * This extension is only applied whenever the link is null or not found
+     * One possible scenario is an internal link has been unpublished
+     * If lots of RedirectorPage then its hard to track and update
+     *
+     * An example use case is to change the content and status code to 404
+     * Another way is to redirect users to existing 404 page
+     *
+     * In this example, this extension only changes the status code to 404 for demonstration
+     *
+     * @see RedirectorPageController::index() as the owner
+     * @param $response
+     * @return void
+     */
+    public function onMissingLinkResponse(&$response)
+    {
+        if ($response instanceof HTTPResponse) {
+            $response->setStatusCode(404);
+        }
+
+        if ($response instanceof DBHTMLText) {
+            $response = new HTTPResponse($response->forTemplate(), 404);
+        }
+    }
+
+}