Laravel5.5+ 使用API Resources快速输出自定义JSON方法详(2)

而Customer对应的customers表中,会有shipping_address_id这个外键指向shipping_addresses表中的id。

那么我们要输出顾客和送货地址,我们需要先在model中定义好relationship:

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Customer extends Model
{
  public function shippingAddress()
  {
    return $this->belongsTo(ShippingAddress::class);
  }
}
<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class ShippingAddress extends Model
{
  public function country()
  {
    return $this->belongsTo(Country::class);
  }
  
  public function province()
  {
    return $this->belongsTo(Province::class);
  }
  
  public function city()
  {
    return $this->belongsTo(City::class);
  }
}

在我们的控制器中,我们拉取出所有客户:

<?php

namespace App\Http\Controllers;

use App\Customer;
use App\Http\Controllers\Controller;

class CustomerController extends Controller
{
  /**
   * Simple function to fetch all customers with their shipping addresses
   *
   * @return String
   */
  public function index()
  {
    $customers = Customer::with(['shippingAddress', 'shippingAddress.country', 'shippingAddress.province', 'shippingAddress.city'])->get();
    
    //这里可以直接返回Eloquent Collections或Objects,toJson()将自动被调用
    return $customers;
  }
}

那么输出的JSON将会包含了多个层级的关系,那么在我们前端调用的时候,将会非常麻烦,因为我们需要一层一层剥开Object关系。

但是如果你熟悉Laravel,你可能会说,慢着!这个情况我可以用accessor不就完事儿了吗?

是的,我们确实可以使用accessor来简化我们的数据层级:

/**
 * Get the customer's full shipping address
 *
 * @return string
 */
public function getFullShippingAddressAttribute()
{
  return "{$this->shippingAddress->country->name} {$this->shippingAddress->province->name} {$this->shippingAddress->city->name} {$this->shippingAddress->address}";
}

但是我们还需要一步操作。由于customers这张表本身没有full_shipping_address这个字段,要使我们的JSON输出包含full_shipping_address,我们需要添加$appends数组:

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Customer extends Model
{
  /**
   * The accessors to append to the model's array form.
   *
   * @var array
   */
  protected $appends = ['full_shipping_address'];
}

对于每一个我们想自定义的JSON字段,我们都需要进行上面两部的操作。这样一来其实非常麻烦,并且不利于代码的维护,因为这会让原本简洁的model显得很复杂。

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