Laravel 自定义数据透视表关系和预加载？

我在为我的一个项目创建架构/模型时遇到问题，希望在这里获得一些帮助。

我目前有 3 个表： Accessories 、 products 和数据透视表 Product_accessory

<?php 

Schema::create('accessories', function(Blueprint $table)
{
    $table->increments('id');
}

Schema::create('products', function(Blueprint $table) 
{
    $table->increments('id');
}

Schema::create('product_accessory', function(Blueprint $table)
{
    $table->increments('id');
    $table->integer('product_id')->unsigned();
    $table->integer('accessory_id')->unsigned();
    $table->foreign('product_id')->references('id')->on('products');
    $table->foreign('accessory_id')->references('id')->on('accessories');
}

现在的问题是我需要添加另一种产品类型“适配器”，它最终取决于数据透视表关系，也就是说，适配器需要与产品和配件相关......

UPDATE这是我当前的product_accessory_adaptor表的样子

Schema::create('product_accessory_adaptor', function(Blueprint $table)
{
    $table->increments('id');
    $table->integer('product_accessory_id')->unsigned();
    $table->foreign('product_accessory_id')->references('id')->on('product_accessory');
}

这样，我可以拥有许多与产品和配件相关的适配器。我的问题是如何用雄辩的方式建模这种关系？

这是我现在所拥有的：

自定义枢轴模型：

class ProductAccessory extends Pivot {
   protected $table = 'product_accessory';

   public function product()
   {
      return $this->belongsTo('Product');
   }

   public function accessory()
   {
     return $this->belongsTo('Accessory');
   }

   public function adaptors() {
     return $this->hasMany('Adaptor', 'product_accessory_id'); 
   } 
}

产品及配件型号

class Accessory extends Eloquent {

   public function products()
   {
      return $this->belongsToMany('Product', 'product_accessory', 'accessory_id', 'product_id')->withPivot();
   }

   public function newPivot(Eloquent $parent, array $attributes, $table, $exists) 
   {
      if ($parent instanceof Product) {
          return new ProductAccessory($parent, $attributes, $table, $exists);
      }
      return parent::newPivot($parent, $attributes, $table, $exists);
   }

   public function adaptors()
   {
      return $this->hasManyThrough('Adaptor', 'ProductAccessory', 'accessory_id', 'product_accessory_id');
   }
}

class Product extends Eloquent {

   public function accessories()
   {
      return $this->belongsToMany('Accessory', 'product_accessory', 'product_id', 'accessory_id')->withPivot();
   }

   public function newPivot(Eloquent $parent, array $attributes, $table, $exists) 
   {
      if ($parent instanceof Accessory) {
          return new ProductAccessory($parent, $attributes, $table, $exists);
      }
      return parent::newPivot($parent, $attributes, $table, $exists);
   }

   public function adaptors()
   {
      return $this->hasManyThrough('Adaptor', 'ProductAccessory', 'product_id', 'product_accessory_id');
   }
}

适配器型号：

class Adaptor extends Eloquent {

   protected $table = 'product_accessory_adaptor';

   public function productAccessory() {
      return $this->belongsTo('ProductAccessory');
   }
}

Update现在架构和模型已设置。然而，使用 hasManyThrough 关系存在一些问题。此外，在这种情况下，有什么方法可以对枢轴关系（即适配器）进行急切加载？

Note当我在产品或配件模型上调用适配器（）时发生的错误是Argument 1 passed to Illuminate\Database\Eloquent\Relations\Pivot::__construct() must be an instance of Illuminate\Database\Eloquent\Model, none given, called in /vendor/laravel/framework/src/Illuminate/Database/Eloquent/Model.php on line 872 and defined

这就是你的支点：

<?php

use Illuminate\Database\Eloquent\Model as Eloquent;

// you don't need to call it ..Pivot, just my suggestion
class ProductAccessory extends Eloquent {

  protected $table = 'product_accessory';

  public function product()
  {
    return $this->belongsTo('Product');
  }

  public function accessory()
  {
    return $this->belongsTo('Accessory');
  }

  public function adaptors()
  {
    return $this->hasMany('Adaptor', 'product_accessory_id');
  }
}

// Product model
public function adaptors()
{
    return $this->hasManyThrough(
      'Adaptor', 'ProductAccessoryPivot', 'product_id', 'product_accessory_id'
    );
}

// Accessory model
public function adaptors()
{
    return $this->hasManyThrough(
      'Adaptor', 'ProductAccessoryPivot', 'accessory_id', 'product_accessory_id'
    );
}

现在示例用法：

$product = Product::first();

$product->adaptors; // collection of all adaptors for given product

$product->adaptors->first()->accessory; // accessory for single adaptor

$product->accessories; // collection of accessories, each with your custom pivot, so:

$product->accessories->first()->adaptors; // collection of adaptors for given product-accessory pair

... and more, try it