Laravel 获取 hasMany 关系上的特定字段

发布于05月04日

I have a hasMany relation function like this:

public function articles()
{
    return $this->hasMany('App\Article');
}

And use it like this:

$data = \App\User::with('articles')->get();

我对它没有任何问题，因为它返回了预期的数据.大概是这样的:

{
"id": 1,
"name": "Jhon",
"lastname": "Doe",
"articles": [
    {
        "id": 1,
        "title": "Article 1",
        "status": "published",
        "published_at": "2015-04-30"
    },
    {
        "id": 2,
        "title": "Article 2",
        "status": "draft",
        "published_at": null
    }
 ]
}

我试图实现但仍然无法实现的是，仅获取关系字段的一个子集即可获得:

{
"id": 1,
"name": "Jhon",
"lastname": "Doe",
"articles": [
    {
        "id": 1,
        "title": "Article 1"
    },
    {
        "id": 2,
        "title": "Article 2"
    }
  ]
}

My intention is to find a way to specify the subset of fields in the Model's function instead of iterating the returning collection and unset the unwanted fields.

这可能吗？

推荐答案

是的，有可能.你有几个 Select .

*NB: For options 1 and 2 below, the foreign key (user_id) must be selected so that Laravel knows how to link the models together when building the relationships.

在使用关系查询时对其进行修改.with()方法可以接受键/值对的数组，其中键是关系的名称，值是修改关系查询的闭包.

 $data = \App\User::with(['articles' => function($query) {
     // user_id is required here*
     $query->select(['id', 'title', 'user_id']);
 }])->get();

创建包含所需字段的新关系.

 public function articleTitles() {
     // user_id is required here*
     return $this->hasMany('App\Article')->select(['id', 'title', 'user_id']);
 }

 $data = \App\User::with('articleTitles')->get();