refactor payment#purchase method, improve environment variable names

app/controllers/payments_controller.rb

@@ -16,7 +16,7 @@ class PaymentsController < ApplicationController
     @payment = Payment.new(payment_params)
     @total_amount_to_pay = Ticket.total_price(@conference, current_user, paid: false)
 
-    if @payment.purchase(current_user, @conference, price_in_cents) && @payment.save
+    if @payment.purchase && @payment.save
       update_purchased_ticket_purchases
       redirect_to conference_conference_registration_path(@conference.short_title), flash: { success: 'Thanks! You have purchased your tickets successfully.' }
     else
@@ -26,10 +26,6 @@ class PaymentsController < ApplicationController
 
   private
 
-  def price_in_cents
-    (@payment.amount * 100).round
-  end
-
   def update_purchased_ticket_purchases
     paid_ticket_purchases = current_user.ticket_purchases.by_conference(@conference).unpaid
     paid_ticket_purchases.each do |ticket|
@@ -40,6 +36,8 @@ class PaymentsController < ApplicationController
   end
 
   def payment_params
-    params.require(:payment).permit(:first_name, :last_name, :credit_card_number, :expiration_month, :expiration_year, :card_verification_value, :amount)
+    params.require(:payment)
+      .permit(:first_name, :last_name, :credit_card_number, :expiration_month, :expiration_year, :card_verification_value, :amount)
+      .merge(user: current_user, conference: @conference)
   end
 end

app/controllers/ticket_purchases_controller.rb

@@ -4,7 +4,7 @@ class TicketPurchasesController < ApplicationController
   authorize_resource :conference_registrations, class: Registration
 
   def create
-    TicketPurchase.destroy_all(user_id: current_user.id, conference_id: @conference.id, paid: false)
+    TicketPurchase.by_conference(@conference).unpaid.by_user(current_user).destroy_all
     message = TicketPurchase.purchase(@conference, current_user, params[:tickets][0])
     if message.blank?
       if current_user.ticket_purchases.by_conference(@conference).unpaid.any?

app/models/payment.rb

@@ -16,6 +16,8 @@ class Payment < ActiveRecord::Base
   validates :expiration_month, presence: true, numericality: { greater_than_or_equal_to: 1, less_than_or_equal_to: 12 }
   validates :expiration_year, presence: true
   validates :amount, presence: true, numericality: { greater_than: 0 }
+  validates :user_id, presence: true
+  validates :conference_id, presence: true
 
   enum status: {
     unpaid: 0,
@@ -34,17 +36,18 @@ class Payment < ActiveRecord::Base
     )
   end
 
-  def purchase(user, conference, price_in_cents)
+  def amount_to_pay
+    Ticket.total_price(conference, user, paid: false).cents
+  end
+
+  def purchase
     gateway_response = begin
-      GATEWAY.purchase(price_in_cents, credit_card, currency: conference.tickets.first.price_currency)
+      GATEWAY.purchase(amount_to_pay, credit_card, currency: conference.tickets.first.price_currency)
     rescue
       ActiveMerchant::Billing::Response.new(false, 'Unable to receive any response from the payment gateway.')
     end
 
-
     if gateway_response.success?
-      self.user_id = user.id
-      self.conference_id = conference.id
       self.last4 = credit_card.display_number
       self.authorization_code = gateway_response.authorization
       self.status = 'success'
@@ -56,4 +59,3 @@ class Payment < ActiveRecord::Base
     success?
   end
 end
-