Laravel Eloquent ORM - 删除行和所有子关系，事件删除

Question

我有三个相互关联的模型:

国家

class Country extends Model
{
    protected $fillable=['name','sort'];
    public $timestamps=false;

    public function region(){
        return $this->hasMany('App\Models\Region');
    }
}

地区

class Region extends Model
{

    protected $fillable=['country_id','name','sort'];
    public  $timestamps=false;

    public function country()
    {
        return $this->belongsTo('App\Models\Country');
    }

    public function city()
    {
        return $this->hasMany('App\Models\City');
    }
}

城市

class City extends Model
{
    protected $table='cities';
    protected $fillable=['region_id','name','sort'];
    public  $timestamps=false;

    public function region()
    {
        return $this->belongsTo('App\Models\Region');
    }
}

当我们自动移除国家时，移除所有子项的关系，即移除和这个国家的地区和城市

我这样做:

模范国家

    public  static function boot() {
        parent::boot();

        static::deleting(function($country) {
            //remove related rows region and city

            // need an alternative variation of this code
            $country->region()->city()->delete();//not working
            $country->region()->delete();

            return true;
        });
    }
}

或者

模型区域

public  static function boot() {
        parent::boot();
        // this event do not working, when delete a parent(country)
        static::deleting(function($region) {
            dd($region);
            //remove related rows city
            $region->city()->delete();
            return true;
        });
    }
}

带有级联删除数据库的选项，请不要提供

更新

我找到了答案

对查询构建器使用闭包，删除相关模型

模范国家

public  static function boot() {
        parent::boot();

        static::deleting(function($country) {
            //remove related rows region and city
            $country->region->each(function($region) {
                $region->city()->delete();
            });
            $country->region()->delete();//
            return true;
        });
    }

Laravel Eloquent ORM - Removing rows and all the inner relationships

Answer 1

简单回顾一下:
$model->related_model将返回相关模型。$model->related_model()将返回关系对象。

你可以做 $model->related_model->delete()或 $model->related_model()->get()->delete()访问 delete()模型上的方法。

处理相关(或子)模型删除的另一种方法是在编写迁移时使用外键约束，检查 https://laravel.com/docs/master/migrations#foreign-key-constraints