php - Laravel 5.1 将关系数据加载到选定行

Question

我的数据库中有一个timesheet 表和一个user 表。以下关系是在 timesheet 模型上设置的。

/**
 * The user that owns the timesheet.
 *
 * @return Object
 */
public function user()
{
    return $this->belongsTo('App\Models\User\User');
}

上面的意思是当我从数据库中选择时间表时，我可以通过使用类似的东西来获取用户数据:

$this->timesheet->whereStatus('Approved')->with('user');

这将在结果中加载用户对象，如果转换为数组将如下所示；

0 => array:13 [▼
    "id" => 1
    "user_id" => 2
    "week" => 1
    "year" => 2016
    "week_ending" => "Sunday 10th January 2016"
    "total_hours" => "45.00"
    "token" => "0e6796a2dc68066c8d36ff828c519af00657db02b733309b8a4ac0f7b5d6a385"
    "status" => "Approved"
    "supervisor_id" => 1
    "approved_by" => 1
    "created_at" => "2016-01-13 15:42:49"
    "updated_at" => "2016-01-14 14:52:07"
    "user" => array:7 [▼
      "id" => 2
      "first_name" => "Bill"
      "last_name" => "Andrews"
      "email" => "Bill.andrews@domain.com"
      "status" => 1
      "created_at" => "2016-01-13 15:38:18"
      "updated_at" => "2016-01-14 14:50:03"
    ]
  ]

但是，我只需要用户表中的first_name 和last_name。有没有一种方法可以将 user 数组与 timesheet 合并/展平，使其看起来像这样；

0 => array:14 [▼
    "id" => 1
    "user_id" => 2
    "week" => 1
    "year" => 2016
    "week_ending" => "Sunday 10th January 2016"
    "total_hours" => "45.00"
    "token" => "0e6796a2dc68066c8d36ff828c519af00657db02b733309b8a4ac0f7b5d6a385"
    "status" => "Approved"
    "supervisor_id" => 1
    "approved_by" => 1
    "created_at" => "2016-01-13 15:42:49"
    "updated_at" => "2016-01-14 14:52:07"
    "first_name" => "Bill"
    "last_name" => "Andrews"
  ]

我试过像这样使用预加载；

$this->timesheet->with(['user' => function ($query) {
    $query->select('first_name', 'last_name');
}])->get()->toArray();

但是，它会产生以下输出；

array:126 [▼
  0 => array:13 [▼
    "id" => 1
    "user_id" => 2
    "week" => 1
    "year" => 2016
    "week_ending" => "Sunday 10th January 2016"
    "total_hours" => "45.00"
    "token" => "0e6796a2dc68066c8d36ff828c519af00657db02b733309b8a4ac0f7b5d6a385"
    "status" => "Approved"
    "supervisor_id" => 1
    "approved_by" => 1
    "created_at" => "2016-01-13 15:42:49"
    "updated_at" => "2016-01-14 14:52:07"
    "user" => null
  ]

Answer 1

第二个示例中用户关系为空的原因是，为了使 Eloquent 关系起作用，它需要绑定(bind)关系的键。换句话说……

1. 获取时间表。
2. 仅使用 first_name 和 last_name 获取 user。
3. 建立关系。
4. 由于您没有获取用户 ID，因此 user's id 和 timesheet's user_id 不匹配，因此无法建立关系。

为了使您的查询有效，您需要像这样调整它:

$this->timesheet->with(['user' => function ($query) {
    $query->select('id', 'first_name', 'last_name');
}])->get()->toArray();

除此之外，如果您想要扁平化的结果，我认为最好使用 joins 而不是预先加载，因为预先加载的性质。

$this->timesheet
     ->join('users', 'timesheets.user_id', '=', 'users.id')
     ->select('timesheets.*', 'users.first_name', 'users.last_name')
     ->get()->toArray();

这假设您的表名称是 users 和 timesheets。