Je pense qu'il y a une meilleure solution que de réécrire le RegistrationsController. J'ai fait exactement la même chose (j'ai juste Organisation au lieu de Compagnie).
Si vous définissez correctement votre formulaire imbriqué, au niveau du modèle et de la vue, tout fonctionne comme un charme.
Mon modèle d'utilisateur:
class User < ActiveRecord::Base
# Include default devise modules. Others available are:
# :token_authenticatable, :confirmable, :lockable and :timeoutable
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable
has_many :owned_organizations, :class_name => 'Organization', :foreign_key => :owner_id
has_many :organization_memberships
has_many :organizations, :through => :organization_memberships
# Setup accessible (or protected) attributes for your model
attr_accessible :email, :password, :password_confirmation, :remember_me, :name, :username, :owned_organizations_attributes
accepts_nested_attributes_for :owned_organizations
...
end
Mon modèle d'organisation:
class Organization < ActiveRecord::Base
belongs_to :owner, :class_name => 'User'
has_many :organization_memberships
has_many :users, :through => :organization_memberships
has_many :contracts
attr_accessor :plan_name
after_create :set_owner_membership, :set_contract
...
end
Mon point de vue: 'devise / registrations / new.html.erb'
<h2>Sign up</h2>
<% resource.owned_organizations.build if resource.owned_organizations.empty? %>
<%= form_for(resource, :as => resource_name, :url => registration_path(resource_name)) do |f| %>
<%= devise_error_messages! %>
<p><%= f.label :name %><br />
<%= f.text_field :name %></p>
<p><%= f.label :email %><br />
<%= f.text_field :email %></p>
<p><%= f.label :username %><br />
<%= f.text_field :username %></p>
<p><%= f.label :password %><br />
<%= f.password_field :password %></p>
<p><%= f.label :password_confirmation %><br />
<%= f.password_field :password_confirmation %></p>
<%= f.fields_for :owned_organizations do |organization_form| %>
<p><%= organization_form.label :name %><br />
<%= organization_form.text_field :name %></p>
<p><%= organization_form.label :subdomain %><br />
<%= organization_form.text_field :subdomain %></p>
<%= organization_form.hidden_field :plan_name, :value => params[:plan] %>
<% end %>
<p><%= f.submit "Sign up" %></p>
<% end %>
<%= render :partial => "devise/shared/links" %>