Laravel 关系之和

Question

我想从我的付款表中返回“金额”的总和。一张发票可以有多次付款。下面的“->sum('amount') 不起作用，它返回：

对非对象调用成员函数 addEagerConstraints()。

如何返回我的关系中每张发票的所有付款总额？

发票型号：

class Invoices extends Eloquent {

    public function payments()
    {
        return $this->hasMany('Payments')->sum('amount');
    }
}

费用模型：

class Payments extends Eloquent {

    public function invoices()
    {
        return $this->belongsTo('Invoices');
    } 
}

我的表“付款”保存表发票的外键，即invoices_id。

Answer 1

从Laravel 8开始，您可以简单地使用withSum()函数。

use App\Models\Post;

$posts = Post::withSum('comments', 'votes')->get();

foreach ($posts as $post) {
    echo $post->comments_sum_votes;
}

https://laravel.com/docs/8.x/eloquent-relationships#other-aggregate-functions

Answer 2

class Invoices extends Eloquent {

    public function payments()
    {
        return $this->hasMany('Payments');
    }
}

class Payments extends Eloquent {

    public function invoices()
    {
        return $this->belongsTo('Invoices');
    } 
}

在你的控制器中

Invoice::with(['payments' => function($query){
   $query->sum('amount');
}])->get();

;