Assert that a user has a paid ticket before registering for a conference.

app/models/conference.rb

@@ -30,6 +30,7 @@ class Conference < ApplicationRecord
   has_many :payments, dependent: :destroy
   has_many :supporters, through: :ticket_purchases, source: :user
   has_many :tickets, dependent: :destroy
+  has_many :registration_tickets, -> { for_registration }, class_name: 'Ticket'
   has_many :resources, dependent: :destroy
   has_many :booths, dependent: :destroy
   has_many :confirmed_booths, -> { where(state: 'confirmed') }, class_name: 'Booth'
@@ -111,6 +112,13 @@ class Conference < ApplicationRecord
     user.present? && registrations.where(user_id: user.id).count > 0
   end
 
+  ##
+  # True when there is at least one ticket marked as "registration"
+  # A user must get a registration ticket before registering.
+  def registration_ticket_required?
+    tickets.for_registration.any?
+  end
+
   ##
   # Delete all EventSchedules that are not in the hours range
   # After the conference has been successfully updated

app/models/registration.rb

@@ -32,6 +32,8 @@ class Registration < ApplicationRecord
     if: -> { conference.try(:code_of_conduct).present? }
   }
 
+  validate :user_has_registration_ticket, if: -> { conference.registration_ticket_required? }
+
   after_create :set_week, :subscribe_to_conference, :send_registration_mail
 
   ##
@@ -65,4 +67,12 @@ class Registration < ApplicationRecord
       errors.add(:base, 'Registration limit exceeded')
     end
   end
+
+  def user_has_registration_ticket
+    return if TicketPurchase.where(user: user, ticket: conference.registration_tickets).paid.any?
+    errors.add(:base, 'You must purchase a registration ticket before registering')
+    if TicketPurchase.where(user: user, ticket: conference.registration_tickets).unpaid.any?
+      errors.add(:base, 'You currently have a ticket with an unfinished purchase')
+    end
+  end
 end