Shopify Scripts - Line Item Properties Discount

line_item_property_discount.rb

Input.cart.line_items.each do |item|
  # ================================================================
  # LINE ITEM PROPERTY DISCOUNT
  # ================================================================
  # Set the line item property in Shopify theme When adding item to cart
  # 
  # line item property is a key/value pair. Example: {"_someCoolPromo": "1"}
  #
  # In this example:
  # "_someCoolPromo" is the key we look for here and must ALWAYS start with an underscore.
  # "1" is the value and respresents a value of $1.00 ("1.25" for $1.25, "1.5" for $1.50 etc.)
  #
  # ================================================================
  ## Check if line item has the specific line item property and if so apply the relevant discount (if greater than sale discount)
  if item.properties.has_key?("_lineItemPropertyKeyHere") && (item.properties["_lineItemPropertyKeyHere"].to_f > 0.00)
    line_item_discount_value = Float(item.properties["_lineItemPropertyKeyHere"])
    discount_amount = Money.new(cents: 100) * line_item_discount_value
    discount_message = "Some Cool Promo"

    ## Check if line item is currently on sale and if so get the sale discount
    if !item.variant.compare_at_price.nil? && item.variant.compare_at_price.cents > 0
      ## Item has compare_at_price, check if is on sale
      if item.variant.compare_at_price > item.variant.price
        ## Item is on sale, apply bundle item discount based on item.variant.compare_at_price
        sale_discount = item.variant.compare_at_price - item.variant.price
        if line_item_discount_value > (Float(sale_discount.cents.to_s) / 100)
          new_line_price = [item.variant.compare_at_price - (discount_amount * item.quantity), Money.zero].max
          item.change_line_price(new_line_price, { message: discount_message })
        end
      else
        ## Item is not on sale, apply line item discount based on item.line_price
        new_line_price = [item.line_price - (discount_amount * item.quantity), Money.zero].max
        item.change_line_price(new_line_price, { message: discount_message }) 
      end
    else
      ## Item does not have compare_at_price, apply line item discount based on item.line_price
      new_line_price = [item.line_price - (discount_amount * item.quantity), Money.zero].max
      item.change_line_price(new_line_price, { message: discount_message })
    end
  end
end

Output.cart = Input.cart