Migrating a Shopify Help Center script template

# ================================ Customizable Settings ================================
# ================================================================
# Tiered Discount by Spend
#
#   If the cart total is greater than (or equal to) an entered
#   threshold, the associated discount is applied to each item.
# ================================================================
SPENDING_THRESHOLDS = [
  {
    threshold: 30,
    discount_type: :percent,
    discount_amount: 10,
    discount_message: '10% off for spending over $30',
  },
  {
    threshold: 60,
    discount_type: :percent,
    discount_amount: 15,
    discount_message: '15% off for spending over $60',
  },
]

# ================================ Script Code (do not edit) ================================
class DiscountApplicator
  def initialize(discount_type, discount_amount, discount_message)
    @discount_type = discount_type
    @discount_message = discount_message

    @discount_amount = if discount_type == :percent
      1 - (discount_amount * 0.01)
    else
      Money.new(cents: 100) * discount_amount
    end
  end

  def apply(line_item)
    new_line_price = if @discount_type == :percent
      line_item.line_price * @discount_amount
    else
      [line_item.line_price - (@discount_amount * line_item.quantity), Money.zero].max
    end

    line_item.change_line_price(new_line_price, message: @discount_message)
  end
end

class TieredDiscountBySpendCampaign
  def initialize(campaigns)
    @campaigns = campaigns
  end

  def run(cart)
    applicable_campaign = nil

    @campaigns.each do |campaign|
      threshold = Money.new(cents: 100) * campaign[:threshold]
      applicable_campaign = campaign if cart.subtotal_price >= threshold
    end

    return if applicable_campaign.nil?

    discount_applicator = DiscountApplicator.new(
      applicable_campaign[:discount_type],
      applicable_campaign[:discount_amount],
      applicable_campaign[:discount_message],
    )

    cart.line_items.each do |line_item|
      discount_applicator.apply(line_item)
    end
  end
end

CAMPAIGNS = [
  TieredDiscountBySpendCampaign.new(SPENDING_THRESHOLDS),
]

CAMPAIGNS.each do |campaign|
  campaign.run(Input.cart)
end

Output.cart = Input.cart

识别为 Spend threshold discount，重建为 spend_goal 类型的优惠。下面是优惠实际保存时使用的配置键，您可以逐项核对自己的重建结果。

基于我们的公开演示店铺 Meridian Goods 搭建，因此这里的每个价格都可以复现，而不必凭信任接受。下方的折扣金额，是结账时运行的同一个引擎针对这个购物车算出的结果。