Actionmailer not recognised rails 3 app - ruby-on-rails

Question

I am trying to send mail using actionmailer on a Rails 3.0.1 application. Here is my setup
config/initializers/setup_mail.rb
ActionMailer::Base.delivery_method = :smtp
ActionMailer::Base.smtp_settings = {
:address => "smtp.gmail.com",
:port => 587,
:domain => "saidyes.co.uk",
:user_name => "username",
:password => "password",
:authentication => "plain",
:enable_starttls_auto => true
}
ActionMailer::Base.default_url_options[:host] = "localhost:3000"
ActionMailer::Base.register_interceptor(DevelopmentMailInterceptor) if Rails.env.development?
config/environments/development.rb
config.action_mailer.raise_delivery_errors = true
config.action_mailer.delivery_method = :smtp
config.action_mailer.perform_deliveries = true
app/mailers/user_mailer.rb
class UserMailer < ActionMailer::Base
default :from => "info#saidyes.co.uk"
def self.registration_confirmation(user)
#user = user
attachments["rails.png"] = File.read("#{Rails.root}/public/images/rails.png")
mail(:to => "#{user.email}", :subject => "Welcome")
end
end
app/models/user.rb
require "#{Rails.root}/app/mailers/user_mailer"
after_create :send_welcome_email
private
def send_welcome_email
UserMailer.registration_confirmation(self).deliver
end
The first error i got was an uninitialized constant UserMailer in my Users model class. I fixed it by adding the require at the top of the User model definition. Now I get
undefined local variable or method `attachments' for UserMailer:Class
I must have configured actionmailer incorrectly or my rails app is not configured correctly to use mailer.
Anyway any advice or help would be appreciated.
Cheers

Answer 1

I think the simple problem you've encountered is that the mail methods should be defined on instances of your mailer class.
Namely it should be
class UserMailer < ActionMailer::Base
def registration_confirmation(user)
#user = user
attachments["rails.png"] = File.read("#{Rails.root}/public/images/rails.png")
mail(:to => "#{user.email}", :subject => "Welcome")
end
end
Note there is no self
Take a look at the helpful Rails Guide on the subject
As in your example you'll still call the method on the class
UserMailer.registration_confirmation(user).deliver
The class method does some magic to instantiate an instance, and ensure the correct template is rendered.