如何在 laravel 急切加载中使用别名答案

【问题标题】：How to use alias in laravel eager loading如何在 laravel 急切加载中使用别名
【发布时间】：2018-01-27 23:59:24
【问题描述】：

我想在 laravel 急切加载中使用别名。这是我的查询

Message::whereIn('conversation_id',$msgs)
        ->where('deleted', '!=', $userId)
        ->with(array('last_sender' =>function($query) use ($userId){
                $query->where('id','!=', $userId);
                $query->select('id', 'userName', 'profilePic','firstName', 'lastName');
          }))

         ->with(array('last_reciever' =>function($query) use ($userId){
                $query->where('id','!=', $userId);
                $query->select('id', 'userName', 'profilePic','firstName', 'lastName');
          }))
         ->orderBy('conversation_id', 'desc') 
         ->orderBy('id', 'desc')
         ->groupBy('conversation_id')
        ->get();

此查询返回用户对象，因为last_sender 和last_reciever 保持为空，或者last_reciever 和last_sender 保持为空。这是此查询返回的结果对象

{
"data": [
    {
        "id": 85,
        "conversation_id": 18,
        "last_reciever": null,
        "last_sender": {
            "id": 39,
            "userName": "df76236sd",
            "profilePic": "aFHZmeMHQ6nd3Ll3nzCqYEw2CTBsun3f1hxm3yKc.jpeg",
            "firstName": "sadek ",
            "lastName": "sdfsd"
        },
        "msg": "abe sala",
        "attachment": null,
        "deleted": 0,
        "seen": 0,
        "created_at": "2017-08-19 02:24:05",
        "updated_at": "2017-08-19 02:24:05"
    },
    {
        "id": 80,
        "conversation_id": 16,
        "last_reciever": {
            "id": 39,
            "userName": "df76236sd",
            "profilePic": "aFHZmeMHQ6nd3Ll3nzCqYEw2CTBsun3f1hxm3yKc.jpeg",
            "firstName": "sadek ",
            "lastName": "sdfsd"
        },
        "last_sender": null,
        "msg": "now should be working just fine",
        "attachment": null,
        "deleted": 0,
        "seen": 1,
        "created_at": "2017-08-19 02:19:34",
        "updated_at": "2017-08-19 02:19:34"
     }
   ]
  }

我想要做的是用自定义名称 oponent 替换 last_sender 和 last_reciever 。为此，我尝试使用类似的东西

Message::whereIn('conversation_id',$msgs)
        ->where('deleted', '!=', $userId)
        ->with(array('last_sender as oponent' =>function($query) use ($userId){
                $query->where('id','!=', $userId);
                $query->select('id', 'userName', 'profilePic','firstName', 'lastName');
          }))

         ->with(array('last_reciever as oponent' =>function($query) use ($userId){
                $query->where('id','!=', $userId);
                $query->select('id', 'userName', 'profilePic','firstName', 'lastName');
          }))
         ->orderBy('conversation_id', 'desc') 
         ->orderBy('id', 'desc')
         ->groupBy('conversation_id')
        ->get();

而且它不起作用。有没有其他方法可以实现这一目标？谢谢。

【问题讨论】：

标签： laravel eloquent laravel-5.4 eager-loading

【解决方案1】：

您可以使用 toArray() 覆盖模型中的值

    public function toArray()
    {
        return [
           'oponent' => $this->last_sender. " " .$this->last_reciever,
        ];
    }

或者使用 laravel api 资源

    class User extends JsonResource
{
    /**
    * Transform the resource into an array.
    *
    * @param  \Illuminate\Http\Request
    * @return array
    */
    public function toArray($request)
    {
        return [
           'id' => $this->id,
           'name' => $this->name,
           'email' => $this->email,
           'created_at' => $this->created_at,
           'updated_at' => $this->updated_at,
       ];
    }
}

如果你想使用 laravel api 资源返回一个集合

Route::get('/user', function () {
    return UserResource::collection(User::all());
});

https://laravel.com/docs/5.6/eloquent-resources

【讨论】：