php - 如何反转 Eloquent Has One 和 Has Many Through (laravel 5.8)？

Question

下面附有三个关系表。

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

我还有三个独立的模型，其中定义了所有表之间的关系。我可以使用 hasManyThrough() 关系从国家/地区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/地区信息。我尝试使用“hasManyThrough”检索城市模型，但没有得到结果(附加为注释国家方法)。请阅读我的模型及其关系方法。

有人可以帮助我使用 Eloquent 方法 hasManyThrough/hasManyThrough 或使用 hasManyThrough/hasManyThrough 的逆来获取城市模型的信息吗？

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

Laravel 中似乎还没有一种本地方法来定义“hasManyThrough”关系的逆关系。有几个issues在github上打开请求它，但他们被关闭了。

您可以使用staudenmeir/belongs-to-through包(如果您不介意为此功能安装第三方包)。然后您应该能够定义一个 belongsToThrough 关系，如下所示:

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

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