php - laravel - 更新与许多 'childs' 的关系

Question

我有这个数据库:
parent

| id |  name  |  
+----+--------+  
|  1 |  Paul  |  
|  2 |  Annet |

children

| id |    name   |  
+----+-----------+  
|  1 |  Micheal  |  
|  2 |   Susan   |

和数据透视表parents_childs

| parent_id | child_id | custom_field_1 | custom_field_2 |  
+-----------+----------+----------------+----------------+  
|     1     |     1    |    value_1     |      (null)    |  
|     2     |     1    |  value_another |     value_3    |

和标准关系belongsToMany

public function parents(): \Illuminate\Database\Eloquent\Relations\BelongsToMany
{
    return $this->belongsToMany('\App\Parent', 'parents_childs', 'child_id', 'parent_id')
                ->withPivot(
                    'custom_field_1',
                    'custom_field_2'
                );
}

现在我需要更新指定子项的数据透视字段，但只针对一个父项，例如。

SET red_value FOR custom_field_2 WHERE child_id = 1 AND parent_id = 2

如果没有 QueryBuilder，我该如何做到这一点？

Answer 1

来自 the docs :

If you need to update an existing row in your pivot table, you may use updateExistingPivot method. This method accepts the pivot record foreign key and an array of attributes to update:

$child = Child::find($childId);
$child->parents()->updateExistingPivot($parentId, ['custom_field_2' => 'red_value']);

https://laravel.com/docs/5.5/eloquent-relationships#updating-many-to-many-relationships