I am creating a web application to integrate with Chargify. I want to return a hash with customer_id set if the user has a customer associated with the account, and customer_attributes if a customer has to be created.

Is there any way that I could do this with an if..end block inside of the hash definition. For example, I would be wanting to do something like the following (does not work):

def subscription_params(product_id)
  {
    :product_id => product_id,
    if customer_id.nil?
      :customer_attributes => customer_params,
    else
      :customer_id => customer_id,
    end
    :credit_card_attributes => credit_card_params
  }
end