为什么在条带量中使用变量时会出现错误？

Question

我试图在我的Stripe.create中显示我的对象（服务）的数量，但是，每当我用一个包含该数字的变量替换该数字时，我从条带得到一个错误400。

我尝试用不同类型的变量替换数字，但似乎只有当我放置一个直接整数时它才有效。

    @service_name = @service.name

    @service_price = @service.price <-- {Tried this but doesn't work.}
    @service_price = 9999 <-- {Tried this and it DOES work.}

    require "stripe"

    Stripe.api_key = Rails.application.credentials.stripe[:secret_key]

    token = params[:stripeToken]

    # Create a Customer:
    customer = Stripe::Customer.create(
        email: @email,
        source: token,
      )

    # Charge the Customer instead of the card:
    charge = Stripe::Charge.create({
        amount: @service.price, <-- {This gives me an error}
        currency: 'usd',
        customer: customer.id,
        description: @service_price <-- {But, this doesn't and it displays correctly}
    })

每项服务都有价格，我希望它只显示该特定关联服务的价格。