FIX display recognisable names for dependent content with no title

Content blocks and other DataObjects that contain HTMLText fields are
also used in the 'Dependent pages' report for each page in the CMS,
however these objects may have neither a Title field, nor a name to
describe them. Instead of showing an empty field in the Title column for
this table, we can instead show "Untitled " with the localised singular
name appended.

code/Model/SiteTree.php

@@ -1978,10 +1978,20 @@ class SiteTree extends DataObject implements PermissionProvider, i18nEntityProvi
                 ->setDisplayFields($dependentColumns)
                 ->setFieldFormatting(array(
                     'Title' => function ($value, &$item) {
+                        $title = $item->Title;
+                        $untitled = _t(
+                            __CLASS__ . '.UntitledDependentObject',
+                            'Untitled {instanceType}',
+                            ['instanceType' => $item->i18n_singular_name()]
+                        );
+                        $tag = $item->hasMethod('CMSEditLink') ? 'a' : 'span';
                         return sprintf(
-                            '<a href="admin/pages/edit/show/%d">%s</a>',
-                            (int)$item->ID,
-                            Convert::raw2xml($item->Title)
+                            '<%s%s class="dependent-content__edit-link %s">%s</%s>',
+                            $tag,
+                            $tag === 'a' ? sprintf(' href="%s"', $item->CMSEditLink()) : '',
+                            $title ? '' : 'dependent-content__edit-link--untitled',
+                            $title ? Convert::raw2xml($title) : $untitled,
+                            $tag
                         );
                     }
                 ));

tests/php/Model/SiteTreeBacklinksTest.php

@@ -6,6 +6,7 @@ use SilverStripe\CMS\Model\SiteTree;
 use SilverStripe\Control\Director;
 use SilverStripe\Control\HTTP;
 use SilverStripe\Dev\SapphireTest;
+use SilverStripe\Forms\GridField\GridField;
 use SilverStripe\Versioned\Versioned;
 
 /**
@@ -21,6 +22,10 @@ class SiteTreeBacklinksTest extends SapphireTest
         ],
     ];
 
+    protected static $extra_dataobjects = [
+        SiteTreeBacklinksTestContentObject::class,
+    ];
+
     public function setUp()
     {
         parent::setUp();
@@ -28,6 +33,14 @@ class SiteTreeBacklinksTest extends SapphireTest
         // Log in as admin so that we don't run into permission issues.  That's not what we're
         // testing here.
         $this->logInWithPermission('ADMIN');
+
+        $page3 = $this->objFromFixture('Page', 'page3');
+        $page3->Content = str_replace(
+            '$page1.ID',
+            $this->objFromFixture('Page', 'page1')->ID,
+            $page3->Content
+        );
+        $page3->write();
     }
 
     public function testSavingPageWithLinkAddsBacklink()
@@ -251,4 +264,28 @@ class SiteTreeBacklinksTest extends SapphireTest
         // assert backlink to page 2 no longer exists
         $this->assertNotContains($page2->ID, $page1->BackLinkTracking()->column('ID'), 'Assert backlink to page 2 has been removed');
     }
+
+    public function testLinkTrackingWithUntitledObjectsDisplaysAReadableIdentifier()
+    {
+        $page = $this->objFromFixture('Page', 'page2');
+
+        $referencingObject = new SiteTreeBacklinksTestContentObject();
+        $referencingObject->Content = '<p><a href="[sitetree_link,id='
+            . $page->ID
+            . ']">Page 2</a></p>';
+        // Title purposely not set - this is the coverage case for this test
+        $referencingObject->write();
+
+        /** @var GridField $gridField */
+        $gridField = $page->getCMSFields()->dataFieldByName('DependentPages');
+
+        // Prepare and sanity check
+        $this->assertNotNull($gridField);
+        $list = $gridField->getList();
+        $this->assertEquals(1, $list->count());
+
+        $content = $gridField->getColumnContent($list->first(), 'Title');
+
+        $this->assertContains('Untitled Backlink test content object', $content);
+    }
 }

tests/php/Model/SiteTreeBacklinksTest.yml

@@ -1,6 +1,5 @@
 Page:
   page1:
-    ID: 1
     Title: page1
     URLSegment: page1
 
@@ -11,7 +10,7 @@ Page:
   page3:
     Title: page3
     URLSegment: page3
-    Content: '<p><a href="[sitetree_link,id=1]">Testing page 1 link</a></p>'
+    Content: '<p><a href="[sitetree_link,id=$page1.ID]">Testing page 1 link</a></p>'
     LinkTracking: =>Page.page1
 
 

tests/php/Model/SiteTreeBacklinksTestContentObject.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace SilverStripe\CMS\Tests\Model;
+
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\ORM\DataObject;
+
+class SiteTreeBacklinksTestContentObject extends DataObject implements TestOnly
+{
+    private static $table_name = 'BacklinkContent';
+
+    private static $db = array(
+        'Title' => 'Text',
+        'Content' => 'HTMLText',
+    );
+
+    private static $singular_name = 'Backlink test content object';
+}