php - 整个产品属于折扣品类吗？

Question

我有这些表:

products
-- name
-- price
-- quantity
-- category_id

discounts
-- type('percentage','numeric')
-- value
-- expired_at

categories 
-- name

discountables
-- discount_id
-- discountable_id
-- discountable_type

在 discountables 中有很多关系:
discounts and categories discounts and products
我已经完成了如何在 discounts and products 之间打折

现在我很困惑如何打折属于我添加到 discountables 的类别的整个产品

关系:

类别模型

public function discounts()
{
    return $this->morphToMany('App\Models\Discount', 'discountable');
}

产品型号

public function discounts()
{
    return $this->morphToMany('App\Models\Discount', 'discountable');
}

折扣模式:

public function categories()
{
    return $this->morphedByMany('App\Models\Category', 'discountable')->withTimestamps();
}

public function products()
{
    return $this->morphedByMany('App\Models\Product', 'discountable')->withTimestamps();
}

直接给产品打折的我的代码 discounts and products

  /**
 * get price of product after discount
 *
 * @return void
 */
public function getDiscountProductAttribute() {
    foreach ($this->discounts as $discount) {
        if($discount->expired_at > Carbon::now()){
            if ($discount->type == 'numeric'){
                return $this->price - $discount->value;
            }else{
                return $this->price - ($this->price * ($discount->value / 100));
            }
        }
    }
}

所以我需要如何打折属于我添加到 discountables 的类别的整个产品？

Answer 1

你们的关系很好。我只是重新设计了一下来解决这个问题。

class Discount extends Model
{
    /**
    * Check whether this discount is expired.
    *
    * return bool
    */
    public function expired()
    {
        // I assume that expired_at is also a Carbon instance.
        return $this->expired_at->isPast();
    }

    /**
    * Return the discount amount for each product.
    *
    * @return double
    */
    public function apply(Product $product)
    {
        if ($this->type === 'numeric') {
            $this->value;
        }

        if ($this->type === 'percentage') {
            return $product->price * ($this->value / 100);
        }

        return 0;
    }
}

class Product extends Model
{
    public function allDiscounts()
    {
        return $this->discounts
            ->merge($this->category->discounts)
            ->unique();
    }

    pubic function getTotalDiscountAttribute()
    {
        return $this->allDiscounts()
            ->reject
            ->expired()
            ->map
            ->apply($this)
            ->sum();
    }

    public function getTotalPriceAttribute()
    {
         return $this->price - $this->total_discount;
    }
}

因此，您可以在应用其自身及其类别(如果有)的各种折扣后，通过简单地说:

$product->total_price;

我希望这有帮助。如果它在任何步骤失败，请告诉我。
顺便一提。你的问题让我想起了几年前的 pretty good speech。它是关于使用继承和空对象模式解决一些类似的问题。它太酷了。您不需要以这种方式重写它，但它是一个非常好的设计。