private function loadBooks() { $categoryId = 1; // load testing books for ($i = 0; $i < 50; $i++) { $book = Books::fetchNew(); $bookId = $book->set('name', 'book' . $i)->set('release_date', '2016-06-24')->save(); $booksCategories = BooksCategories::fetchNew(); $booksCategories->set('book_id', $bookId)->set('category_id', $categoryId++); $booksCategories->save(); if ($categoryId == 4) { $categoryId = 1; } } }