约束Eager Loads

Question

我需要重构我的数据关系，因为包含了日期。我有三种模式：

\App\Product;
discounts()->hasManyThrough('App\Discount', 'App\DiscountProduct', 'product_id','id','id','discount_id');
\App\DiscountProduct;
discount()->belongsTo('App\Discount', 'discount_id');
\App\Discount;
discountProduct()->hasMany('App\DiscountProduct');

discounts_product表：id，discount_id，product_id
折扣表：id，name，start_date，end_date等。
产品表：id，名称，价格等

当我致电$product->with('discounts')时结果是这样的

{"id": 1,
 "name": "Wild Blue Shirt",
 "discounts": [{
     "method": "per_product",
     "type": "percentage",
     "nominal": 10,
     "start_date": "2018-03-01 16:34:50", <= this is my problem
     "end_date": "2018-03-31 16:34:50", <= this is my problem
      },...other expired discounts],
},...other products

我的问题是：如何过滤每种产品的当前（今天）折扣？

我试过这个：

\App\DiscountProduct;
currentDiscount() {
   return $this->belongsTo("App\Discount", 'discount_id')->whereRaw('now() BETWEEN start_date AND end_date');
};

然后

$product->with('discounts.currentDiscount'); <= doesn't worked

这对我有用：

$product_list = $products->with('variants')->with('discounts')->get();
$product_list->transform(function($product) use ($discounts){
   $data = $product;
   $currentDiscount = collect($product->discounts)->map(function($discount){
       $data = null;
       if($discount['end_date'] > now()){
            $data = $discount;
       };
       return $data;
       });
    $data->currentDiscount = $currentDiscount->filter()->first();
    return $data;
});

但问题是我无法使用paginate()功能，使用forpage()非常痛苦

否则这个原始数据库也可以使用：

$products = DB::table('products')
->selectRaw("products.id, products.name, products.price, COALESCE(active_discount.discount_amount,0) AS discount")
->leftJoin(DB::raw("(discount_products.product_id, CAST(IF(discounts.`type`='percentage', ROUND((discounts.nominal/100)*products.price,0) ,discounts.nominal) AS UNSIGNED) AS discount_amount FROM discount_products JOIN discounts ON discount_products.discount_id=discounts.id JOIN products ON discount_products.product_id=products.id WHERE NOW() BETWEEN discounts.start_date AND discounts.end_date ) active_discount"),'products.id', '=', 'active_discount.product_id'));

我不认为以上所有方法都是最佳解决方案。请帮忙。

Answer 1

我认为您的问题[与分页/等]是因为您正在制作Raw DB请求而不是使用Eloquent。

你可以constrain Eager Loading：

约束Eager Loads

有时您可能希望加载关系，但也要指定   急切加载查询的附加查询约束。这是一个   例如：
$users = App\User::with(['posts' => function ($query) {
    $query->where('title', 'like', '%first%');

}])->get();
在这个例子中，Eloquent只会急切地加载帖子的帖子标题栏包含第一个单词。当然，你可以打电话给其他人查询构建器方法，以进一步自定义预先加载操作：
$users = App\User::with(['posts' => function ($query) {
    $query->orderBy('created_at', 'desc');

}])->get();

所以在你的情况下，你可以做（没有测试它，但这应该有效）：

$product->with(['discounts' => function ($query) {

        $query->where(['start_date' , '<', now()] , ['end_date', '>' , now()]);

        }])->paginate(10);

您也可以直接在关系中在模型中设置它：

public function currentDiscount()
    {
        return $this->belongsTo('App\Discount', 'discount_id')
            ->where(
                ['start_date', '<', now()],
                ['end_date', '>', now()]
            );
    }

Laravel有很多关于日期验证的低谷

1 个答案:

约束Eager Loads