Nested objects in form not validating - ruby-on-rails

Question

I have a nested form where users can book appointments. However, I've noticed an issue with the form where a user can fill out the required Client model fields and not the required Appointment model fields and the form still submits since for some reason the validation on the Appointment model isn't being triggered. The only time the Appointment validation is triggered is when the associated form fields are populated. How do I get the nested form to verify that the Appointment fields are being filled out? Since clients can have multi
Customer model:
class Customer < ActiveRecord::Base
has_many :appointments
accepts_nested_attributes_for :appointments
attr_accessible :name, :email, :appointments_attributes
validates_presence_of :name, :email
validates :email, :format => {:with => /^[^#][\w.-]+#[\w.-]+[.][a-z]{2,4}$/i}
validates :email, :uniqueness => true
end
Appointment model:
class Appointment < ActiveRecord::Base
belongs_to :customer
attr_accessible :date
validates_presence_of :date
end
Customers controller:
class CustomersController < ApplicationController
def new
#customer = Customer.new
#appointment = #customer.appointments.build
end
def create
#customer = Customer.find_or_initialize_by_email(params[:customer])
if #customer.save
redirect_to success_customers_path
else
# Throw error
#appointment = #customer.appointments.select{ |appointment| appointment.new_record? }.first
render :new
end
end
def success
end
end
Customers form view:
= simple_form_for #customer, :url => customers_path, :method => :post, :html => { :class => "form-horizontal" } do |customer_form|
= customer_form.input :name
= customer_form.input :email
= customer_form.simple_fields_for :appointments, #appointment do |appointment_form|
= appointment_form.input :date
UPDATE: Providing routes
resources :customers, :only => [:new, :create] do
get :success, :on => :collection
end

Answer 1

If a customer has to have an appointment:
class Customer < ActiveRecord::Base
has_many :appointments
accepts_nested_attributes_for :appointments
attr_accessible :name, :email, :appointments_attributes
validates_presence_of :name, :email, :appointment # <- add your appointment
....
end
This will require each customer has at least one appointment.
EDIT based on comment
Instead of using build in your controller, I think you can use create instead which will then associate that appointment with the customer and force validation.
Customers controller:
def edit
#customer = Customer.find_or_initialize_by_email(params[:customer])
#appointment = #customer.appointments.create
end
And you'd do the same in your new method