关联查询

1. 运行环境

1). 当前使用的 Laravel 版本？

8.x

2). 当前使用的 php/php-fpm 版本？

PHP 版本：7.4

php-fpm 版本：

3). 当前系统

Windows 10

4). 业务环境

5). 相关软件版本

2. 问题描述？

$list = BookCategory::query()
            ->with(['book' => function ($query) {
                $query->where('status', 1)->orderByDesc('sorts')->select('id', 'name');
            }])
            ->get()
            ->toArray();

为什么加上->select('id', 'name')后关联数据为[]如下：

array:1 [
  0 => array:7 [
    "id" => 1
    "name" => "山"
    "sorts" => 0
    "status" => 1
    "created_at" => "2023-04-14 14:43:00"
    "updated_at" => "2023-04-14 14:43:00"
    "book" => []
  ]
]

而去除掉->select('id', 'name')却正确返回关联数据，如下：

array:1 [
  0 => array:7 [
    "id" => 1
    "name" => "山"
    "sorts" => 0
    "status" => 1
    "created_at" => "2023-04-14 14:43:00"
    "updated_at" => "2023-04-14 14:43:00"
    "book" => array:1 [
      0 => array:15 [
        "id" => 1
        "category_id" => 1
        "name" => "渊海子平"
        "author" => "徐太升"
        "dynasty" => "宋"
        "wordage" => "30.95"
        "read_num" => 0
        "imgurl" => "images/2023/04/14/4613b62021733552b8cb6cb19f101ec1.jpeg"
        "press" => "未知"
        "add_bookshelf_num" => 0
        "sorts" => 0
        "status" => 1
        "created_at" => "2023-04-14 16:18:25"
        "updated_at" => "2023-04-14 16:27:21"
      ]
    ]
  ]
]

3. 您期望得到的结果？

4. 您实际得到的结果？