album.rb

class Album < ActiveRecord::Base
  attr_accessible :title
  has_one :artist , :dependent => :destroy
  has_many :genres , :dependent => :destroy

  accepts_nested_attributes_for :artist, :allow_destroy => true
end

artist.rb

class Artist < ActiveRecord::Base
  belongs_to :album

  def full_name 
    return self.first_name + ' ' + self.surname
  end
end

controller.rb

def new
    @album = Album.new
    @album.build_artist(:first_name => "garren")
end

form.rb

<%= form_for @album do |f| %>
  <%= f.error_messages %>
  <p>
    <%= f.label :title %><br />
    <%= f.text_field :title %>
    </p>
    <% f.fields_for :artist do |artist| %>
   <p>
    <%= artist.label :first_name %><br />
    <%= artist.text_field :first_name %>
    </p>
      <% end %>

    <p><%= f.submit %></p>
<% end %>