Laravel 5.6 Eloquent 方法不返回数据

在我的User班级中，我有以下关系：

/**
 * Roles of a User
 *
 * @return \Illuminate\Database\Eloquent\Relations\hasManyThrough
 */
public function roles()
{
    return $this->hasManyThrough(Role::class, UserRole::class, 'user_id', 'id');
}

我创建了一个方法来根据传入的角色返回布尔值：

/**
 * Is User of a given Role?
 *
 * @return bool
 */
public function hasRole($roleShort = null)
{
    if (!$roleShort) {

        return false;

    }

    $result = $this->roles
        ->where('roles.short', '=', $roleShort)
        ->first();

    return $result ? true : false;
}

在Tinker我得到第一个用户并返回他的角色，它按预期工作正常。但是当我将角色短名称传递给hasRole方法时，它总是返回 false。

>>> $u = User::find(1);
[!] Aliasing 'User' to 'App\Models\User' for this Tinker session.
=> App\Models\User {#839
     id: 1,
     uuid: "4e86a284-ae1f-4753-a243-797dc5ce98fc",
     name: "Test User",
     email: "[email protected]",
     country_id: 11,
     partner_id: null,
     region_id: 1,
     language_id: 1,
     time_zone_id: 387,
     date_format_id: 1,
     time_format_id: 11,
     date_time_format_id: 13,
     activated_at: "2018-04-01 14:00:00",
     deleted_at: null,
     created_at: "2018-04-01 22:53:32",
     updated_at: "2018-04-01 22:53:32",
   }

>>> $u->roles
=> Illuminate\Database\Eloquent\Collection {#820
     all: [
       App\Models\Role {#827
         id: 1,
         partner: 0,
         name: "Admininstrator",
         short: "ADMIN",
         user_id: 1,
       },
     ],
   }

>>> $u->hasRole('ADMIN');
=> false

我错过了什么？我尝试记录 SQL 查询，但出现以下错误：

Log::info($this->roles
    ->where('roles.short', '=', $roleShort)
    ->first()
    ->toSql());

>>> $u->hasRole('ADMIN');
PHP Error:  Call to a member function toSql() on null in /home/vagrant/src/sdme/app/Models/User.php on line 126