Error while adding subtotal_price line item script

[akshat001]

Hi All,

Shopify has a limitation that it does not send the discount information in the carrier service API. As a carrier service API provider, I need the discount information to set my rates accordingly. 

To overcome this limitation, I am exploring the line item script where I can access the cart and the included discount information. In the script, I am calculating the cart subtotal leaving the discount information and trying to send it in the line item properties field. However, the script is not allowing me to add the Money object to the properties object. 

Below is my code.

cart = Input.cart

Input.cart.line_items.each do |line_item|
line_item.change_properties({"_cart_details"=>{"discounted_value"=> cart.subtotal_price }},message:"subtotal")
end

Output.cart = Input.cart

The script editor is throwing the below error.

Can anyone please help?