如何反转 Eloquent has one and has many through (laravel 5.8)？

Question

我在下面附上了三个关系表。

https://drive.google.com/file/d/1q1kdURIwFXxHb2MgdRyBkE1e3DMug7r-/view?usp=sharing

我还有三个单独的模型，其中定义了我所有表之间的关系。我可以使用hasManyThrough() 关系从国家模型中读取城市模型的信息，但无法从城市模型中读取国家信息。我尝试使用“hasManyThrough”检索城市模型，但没有得到结果（作为评论国家方法附加）。请在这里阅读我的模型和它的关系方法..

是否有人可以帮助我使用 Eloquent 方法 hasManyThrough / hasManyThrough 或使用逆 hasManyThrough / hasManyThrough 获取城市模型的信息？

01.

<?php

namespace App\Hrm;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;

class Country extends Model
{
    //use SoftDeletes;
    protected $fillable = ['name','description','status'];


    public function districts(){
        return $this->hasMany(District::class);
    }


    public function cities(){
        return $this->hasManyThrough(City::class,District::class);
    }


}

02.

<?php

namespace App\Hrm;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;

class District extends Model
{
    //use SoftDeletes;
    protected $fillable = ['country_id','name','description','status'];


    public function country(){
        return $this->belongsTo(Country::class);
    }

    public function cities(){
        return $this->hasMany(City::class);
    }

}

3.

namespace App\Hrm;

use App\User;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;

class City extends Model
{
    //use SoftDeletes;
    protected $fillable = ['district_id','name','description','status'];

    public function district(){
        return $this->belongsTo(District::class);
    }

//    public function country(){
//        return $this->hasOneThrough(Country::class, District::class);
//    }

Answer 1

在 Laravel 中似乎还没有一种本地方式来定义“hasManyThrough”关系的逆向。在 github 上打开了几个issues 请求它，但它们被关闭了。

如果您不介意为此功能安装第三方软件包，您可以使用staudenmeir/belongs-to-through 软件包。然后你应该能够像这样定义belongsToThrough 关系：

class City extends Model
{
    use \Znck\Eloquent\Traits\BelongsToThrough;

    public function country() {
        return $this->belongsToThrough(Country::class, District::class);
    }
}

Answer 2

为什么不能使用父方法？

$city = City::find(1);
$country = $city->district->country();