关联表的数据再次提交的时候没有修改而是重复添加

// 关联产品相册
public function ProductImgs()
{
    return $this->hasMany(ProductImg::class, 'product_id');
}Copy

public  function  product()
{
    return  $this->belongsTo(Product::class, 'id');
}Copy

protected  function  form()
{
    $repository = new  Product(['Category', 'ProductImgs']);
    return  Form::make($this->product = $repository, function (Form  $form) {
     $form->tab('产品相册', function (Form  $form) {
     $form->hasMany('ProductImgs', '产品相册', function (Form\NestedForm  $form) {
    $form->display('product_img_id','产品图片ID');
    $form->image('url','图片地址')->uniqueName()
    ->move('images/'  .  date('Ymd', time()));
    $form->number('sort','排序');
    })->useTable();
});
});
}Copy