Question

My Route

  scope :module => "group" do
    resources :groups do 
      resources :topics
    end
  end

My model

class Post < ActiveRecord::Base
  belongs_to :group
end

class Group < ActiveRecord::Base
  has_many :posts
end

class Group::Topic < Post
end

My form:

<%= simple_form_for [@current_group, @topic], :html => {:id => "post_form", :class => 'form-horizontal'} do |f| -%> 
end

The error message is

undefined method `group_group_topics_path’ for

Answer 1

I don’t think the case is in simple_form. Most likely you have an error in your routes and they should be updated as follows:

scope :module => "group" do
  resources :groups do 
    scope :module => :groups do
      resources :topics
    end
  end
end

Then you will get group_group_topics_path route working. To see all the topics routes type this command in the console: rake routes | grep 'topics'.