Added regenerate-references command test

Also updated model resolvers to only fetch model ID, to prevent bringing
back way more data from database than desired.

app/References/ModelResolvers/BookLinkModelResolver.php

@@ -19,7 +19,7 @@ class BookLinkModelResolver implements CrossLinkModelResolver
         $bookSlug = $matches[1];
 
         /** @var ?Book $model */
-        $model = Book::query()->where('slug', '=',  $bookSlug)->first();
+        $model = Book::query()->where('slug', '=',  $bookSlug)->first(['id']);
 
         return $model;
     }

app/References/ModelResolvers/BookshelfLinkModelResolver.php

@@ -19,7 +19,7 @@ class BookshelfLinkModelResolver implements CrossLinkModelResolver
         $shelfSlug = $matches[1];
 
         /** @var ?Bookshelf $model */
-        $model = Bookshelf::query()->where('slug', '=',  $shelfSlug)->first();
+        $model = Bookshelf::query()->where('slug', '=',  $shelfSlug)->first(['id']);
 
         return $model;
     }

app/References/ModelResolvers/ChapterLinkModelResolver.php

@@ -20,7 +20,7 @@ class ChapterLinkModelResolver implements CrossLinkModelResolver
         $chapterSlug = $matches[2];
 
         /** @var ?Chapter $model */
-        $model = Chapter::query()->whereSlugs($bookSlug, $chapterSlug)->first();
+        $model = Chapter::query()->whereSlugs($bookSlug, $chapterSlug)->first(['id']);
 
         return $model;
     }

app/References/ModelResolvers/PageLinkModelResolver.php

@@ -20,7 +20,7 @@ class PageLinkModelResolver implements CrossLinkModelResolver
         $pageSlug = $matches[2];
 
         /** @var ?Page $model */
-        $model = Page::query()->whereSlugs($bookSlug, $pageSlug)->first();
+        $model = Page::query()->whereSlugs($bookSlug, $pageSlug)->first(['id']);
 
         return $model;
     }

app/References/ModelResolvers/PagePermalinkModelResolver.php

@@ -18,7 +18,7 @@ class PagePermalinkModelResolver implements CrossLinkModelResolver
 
         $id = intval($matches[1]);
         /** @var ?Page $model */
-        $model = Page::query()->find($id);
+        $model = Page::query()->find($id, ['id']);
 
         return $model;
     }

app/References/ReferenceService.php

@@ -23,7 +23,7 @@ class ReferenceService
     {
         Reference::query()
             ->where('from_type', '=', (new Page())->getMorphClass())
-            ->truncate();
+            ->delete();
 
         Page::query()->select(['id', 'html'])->chunk(100, function(Collection $pages) {
             $this->updateForPages($pages->all());

tests/Commands/RegenerateReferencesCommandTest.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace Tests\Commands;
+
+use BookStack\Entities\Models\Page;
+use Illuminate\Support\Facades\DB;
+use Tests\TestCase;
+
+class RegenerateReferencesCommandTest extends TestCase
+{
+    public function test_regenerate_references_command()
+    {
+        /** @var Page $page */
+        $page = Page::query()->first();
+        $book = $page->book;
+
+        $page->html = '<a href="' . $book->getUrl() . '">Book Link</a>';
+        $page->save();
+
+        DB::table('references')->delete();
+
+        $this->artisan('bookstack:regenerate-references')
+            ->assertExitCode(0);
+
+        $this->assertDatabaseHas('references', [
+            'from_id' => $page->id,
+            'from_type' => $page->getMorphClass(),
+            'to_id' => $book->id,
+            'to_type' => $book->getMorphClass(),
+        ]);
+    }
+}