php - Laravel 多个 belongsTo 用户

Question

我正在尝试显示 Races + 参加比赛的人，我正在使用表关系，但我不确定我是否正确使用它。

查看:

@foreach($leagues->races as $race)
        <!-- ATTENDANCE track -->
        <div class="col s12 m6">
          <div class="card">
            <div class="card-image">
              <img src="{{ asset("img/tracks/.png") }}">
              <span class="card-title red attendance-track-box"><b>{{$race->event}}</b></span>
            </div>
            <div class="card-content attendance-content">
                <ul>
                  @foreach($race->attendances as $attendance)
                    @if($attendance->status == 1)
                      <li class="border-left-green">{{$attendance->user->username}}</li>
                    @elseif($attendance->status == 2)
                      <li class="border-left-red"></li>
                    @elseif($attendance->status == 3)
                      <li class="border-left-cyan"></li>
                    @endif
                  @endforeach
                </ul>
            </div>
            <div class="card-action">
              <a class="waves-effect waves-light btn green">Yes</a> <a class="waves-effect waves-light btn red">No</a> <a class="waves-effect waves-light btn">Maybe</a>
            </div>
          </div>
        </div>
        @endforeach

模型联赛:

class Leagues extends Model
{
    //
    public function teams(){
        return $this->hasMany('App\teams');
    }
    public function races(){
        return $this->hasMany('App\races');
    }
}

模型比赛:

class Races extends Model
{
    //
    public function attendances()
    {
        return $this->hasMany('App\attendances');
    }
}

模型驱动程序:(将此用于驱动程序列表)

class Drivers extends Model
{
    //
    public function user(){
        return $this->belongsTo('App\Users', 'users_id', 'id');
    }
}

模型出勤:

class attendances extends Model
{
    //
    public function user(){
        return $this->belongsTo('App\Users', 'users_id', 'id');
    }
}

模型用户

namespace App;

use Illuminate\Database\Eloquent\Model;

class Users extends Model
{
    //
}

我已经发布了 Drivers 模型，因为我也调用了 belongsTo。 基本上，我已经复制了代码，它适用于司机，但不适用于出勤

我得到的错误:

Trying to get property 'username' of non-object

用户.php

<?php

namespace App;

use Illuminate\Notifications\Notifiable;
use Illuminate\Foundation\Auth\User as Authenticatable;

class User extends Authenticatable
{
    use Notifiable;

    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'username', 'psn', 'email', 'password',
    ];

    /**
     * The attributes that should be hidden for arrays.
     *
     * @var array
     */
    protected $hidden = [
        'password', 'remember_token',
    ];
}

Answer 1

你的模型关系只是在做相反的 belongsTo。如果您想使用 belongsTo，您的模型关系需要双向进行，但您的关系只会反向进行。首先使用 hasMany、hasOne 等定义关系，然后您可以在其他模型中定义逆。

示例驱动程序:

class Drivers extends Model
{
    public function user(){
        return $this->belongsTo('App\Users', 'users_id', 'id');
    }
}

出席示例:

class attendances extends Model
{
     public function user(){
         return $this->belongsTo('App\Users', 'users_id', 'id');
     }
}

示例用户:

class Users extends Model
{
     public function attendances()
     {
         return $this->hasMany('App\attendances');
     }

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

每个类都需要相互引用。一个使用 hasMany、hasOne 等来定义关系，另一个需要 belongsTo 来定义相反的关系。