函数无法加载有很多关系数据 laravel 模型 Eloquent

Question

我有这两个型号。这个 phone 模型是一个通用模型，可用于保存和获取用户、客户、员工等的 phone 值。所以meta_value用于保存相关模型的id，meta_key用于确定模型名称关系。

/* Customer Model*/
namespace App;    
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;

class Customer extends Model {
    /**
     * Get the Phone List.
     */
    public function phones(){
        return $this->hasMany('App\Phone','meta_value', 'id')
                    ->select('id as phone_id','contact_number as phone','contact_number','country_code','type','dial_code')
                    ->where('meta_key','customer');
    }
}
/* Phone Model*/
namespace App;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;


class Phone extends Model {
    /**
     * Get the customer that owns the phone.
     */
    public function customer(){
        return $this->belongsTo('App\Customer', 'meta_value');
    }
}

我无法获取带有客户数据的 phones 的数据。它总是 returns

[relations:protected] => Array
    (
        [phones] => Illuminate\Database\Eloquent\Collection Object
            (
                [items:protected] => Array
                    (
                    )

            )

    )

在我的控制器中，我执行以下代码。

/*This is the case when I want to get the data for a single customer.*/
        $customer = Customer::find('448')->with('phones')->get();
        print_r($customer); // It will return all customers with no phones value.

        $customer = Customer::find('448');
        print_r($customer);die; // It will return a single customer whose id is 448 with no phones value.

        print_r($customer->phones);die; // I can get the values of phones by this

        $customer = Customer::find('448')->with('phones');
        print_r($customer);die; // It will crash my postman when i hit this.

        /*This is the case when I want to get the data for multiple customers.*/
        $customers = Customer::where('id', '>', '447')->with('phones')->get();
        print_r($customers);die; // It will return multiple customer with empty phones value.

        // However when I iterate through the loop and get phones then I can get the phone value. 
        $customers = Customer::where('id', '>', '447')->get();
        foreach ($customers as $customer) {
            $customer->phones = $customer->phones;
        }
        print_r($customers);die;

只有迭代有效，但我认为这不是一个好的解决方案。即使我尝试加载功能，但没有工作。

Answer 1

虽然我怀疑选择 phone_id 作为 id 可能会影响检查关系的查询，但快速调试将是从相关函数中删除它：

->select('id as phone_id','contact_number as phone','contact_number','country_code','type','dial_code')
                ->where('meta_key','customer');

让函数 phones 变得简单，

public function phones(){
    return $this->hasMany('App\Phone','meta_value', 'id');
}

~已更新~

然后，您需要改用load。

如果以后需要进一步检查关系，则通过回调对其进行过滤：

$customer = Customer::find('448')->load(['phones' => function($query) {
    $query->where('meta_key','customer');
}]);

或：

$customer = Customer::with(['phones' => function($query) {
    $query->where('meta_key','customer');
}])->find('448');

最初的问题是：

在 find 的结果上使用 with 和 get 会为新查询创建模型的另一个实例，因此您只会获得客户的所有记录。您可以使用 load 方法，或者如果您将使用 with 则必须在查询函数的末尾设置过滤器。

为了更好地理解，请查看 Laravel documentation on Eager Loading

Answer 2

您必须 select 所需的外键列 meta_value:

->select('id as phone_id','contact_number as phone','contact_number','country_code',
    'type','dial_code','meta_value')

对于单个客户，您不需要预先加载：

$customer = Customer::find(448);
$phones = $customer->phones;

看起来你也应该使用 polymorphic relationships。

函数无法加载有很多关系数据 laravel 模型 Eloquent

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