Laravel 自定义数据透视表关系和急切加载？

Question

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：附件、产品和数据透视表 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个最终取决于数据透视表关系的产品类型“适配器”，也就是说，适配器需要与产品和附件相关...

更新 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 eloquent 建模这种关系？

这是我现在拥有的：

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');
   }
}

更新 现在模式和模型已设置。但是，使用 hasManyThrough 关系存在一些问题。此外，在这种情况下，有什么方法可以为枢轴关系（即适配器）进行预加载？

注意 当我在 Product 或 Accessory 模型上调用 adapters() 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

Answer 1

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