BookStack\Book::chapters PHP Méthode

    public function chapters()
    {
        return $this->hasMany(Chapter::class);
    }

 /**
  * Get all child objects of a book.
  * Returns a sorted collection of Pages and Chapters.
  * Loads the book slug onto child elements to prevent access database access for getting the slug.
  * @param Book $book
  * @param bool $filterDrafts
  * @return mixed
  */
 public function getChildren(Book $book, $filterDrafts = false)
 {
     $pageQuery = $book->pages()->where('chapter_id', '=', 0);
     $pageQuery = $this->permissionService->enforcePageRestrictions($pageQuery, 'view');
     if ($filterDrafts) {
         $pageQuery = $pageQuery->where('draft', '=', false);
     }
     $pages = $pageQuery->get();
     $chapterQuery = $book->chapters()->with(['pages' => function ($query) use($filterDrafts) {
         $this->permissionService->enforcePageRestrictions($query, 'view');
         if ($filterDrafts) {
             $query->where('draft', '=', false);
         }
     }]);
     $chapterQuery = $this->permissionService->enforceChapterRestrictions($chapterQuery, 'view');
     $chapters = $chapterQuery->get();
     $children = $pages->values();
     foreach ($chapters as $chapter) {
         $children->push($chapter);
     }
     $bookSlug = $book->slug;
     $children->each(function ($child) use($bookSlug) {
         $child->setAttribute('bookSlug', $bookSlug);
         if ($child->isA('chapter')) {
             $child->pages->each(function ($page) use($bookSlug) {
                 $page->setAttribute('bookSlug', $bookSlug);
             });
             $child->pages = $child->pages->sortBy(function ($child, $key) {
                 $score = $child->priority;
                 if ($child->draft) {
                     $score -= 100;
                 }
                 return $score;
             });
         }
     });
     // Sort items with drafts first then by priority.
     return $children->sortBy(function ($child, $key) {
         $score = $child->priority;
         if ($child->isA('page') && $child->draft) {
             $score -= 100;
         }
         return $score;
     });
 }