Question

I have two models: user and profile. I would like to use the same form to input data to both at the same time. I was following railscast 196# about Nested Model Form (revised). The problem is, the first part of the form is being generated just fine. It’s the second part (where field_for is used), that does not show in the view.
I searched stackoverflow for a solution and it was suggested to use a ‘build’ action somehow. That, however, did not work, due to an error.

I would really appreciate it if someone could explain how I can make it work. I have been struggling with this issue for a few days now.

user.rb
class User < ActiveRecord::Base
attr_accessible :email, :first_name, :last_name, :orientation, :gender, :password, :password_confirmation, :date_joined, :last_online, :date_of_birth, :location, :profiles_attributes  
    has_one :profiles   
    accepts_nested_attributes_for :profiles, allow_destroy: true                    
    has_secure_password
    validates_confirmation_of :password
    #.....#
end

profile.rb
class Profile < ActiveRecord::Base
    attr_accessible :height, :weight
    belongs_to :user
end

user/new.html.erb
<%= form_for @user do |f| %>
    <% if @user.errors.any? %>
    <div class="error_messages">
      <h2>Form is invalid</h2>
      <ul>
        <% for message in @user.errors.full_messages %>
          <li><%= message %></li>
        <% end %>
      </ul>
    </div>
  <% end %>
        <%= f.label :gender, "I am a:" %><%= f.select :gender, options_for_select([["Man", "Male"], ["Woman", "Female"]]) %><br />
        <%= f.label :orientation, "Sexsual Orientation" %><%= f.select :orientation, options_for_select([["Straight", "Straight"], ["Gay", "Gay"], ["Bi","Bi"]]) %><br />
        <%= f.label :first_Name %><br /><%= f.text_field :first_name %><br />
        <%= f.label :last_name %><br /><%= f.text_field :last_name %><br />
        Date of Birth:<%= f.date_select( :date_of_birth, :start_year => 1920, :prompt => { :day => 'day', :month => 'month', :year => 'year' }) %><br />
        <%= f.label :location %><br /><%= f.text_field :location %><br />
        <%= f.label :email %><br /><%= f.text_field :email %><br />
        <%= f.label :password %><br /><%= f.password_field :password %><br />
            <%= f.label :password_confirmation %><br /><%= f.password_field :password_confirmation %><br />

        <%= f.fields_for :profiles do |builder| %>
          <fieldset>
            <%= builder.label :height, "My height is: (cm)" %><%= builder.text_field :height %><br />
            <%= builder.label :weight, "My weight is: (kg)" %><%= builder.text_field :weight %>
          </fieldset>
        <% end %>
    <%= f.submit "Next" %>
<% end %>

<%= link_to 'Back', users_path %>

edit:
new action in user_controller:
(as you can see it’s pretty standard)

  def new       
    @user = User.new


    respond_to do |format|
      format.html # new.html.erb
      format.json { render json: @user }
    end
  end

Answer 1

I think you need

has_one :profile

in your user model.

Make the form do

 fields_for :profile

And in your users_controller do

@user = User.new
@user.build_profile

has_one relationships work a little differently to has_many – see http://guides.rubyonrails.org/association_basics.html#has_one-association-reference