gistfile1.rb

# teams/new.html.haml
-form_for([@team]) do |f| 
  = link_to_function 'Add a Member' { |page| page.insert_html :bottom, :members, :partial => 'member', :object => Member.new } 
  = f.submit 
 
# teams/_member.html.haml
- fields_for 'team[member_attributes][]', member do |f| 
= f.datetime_select  :arrival 
 
# teams_controller.rb
def create 
  @team = Team.new(params[:team]) 
  @members = @team.members 
end 
 
# models/team.rb
def member_attributes=(attributes) 
  attributes.each do |a| 
    members.build(a) 
  end 
end