What is the proper way to create an object with a belongs_to association?

Question

I'm pretty new to rails, and I have some trouble getting the philosophy and finding the "proper" way to create an object as a dependency of an other one.

I have a Backlog model :

class Backlog < ActiveRecord::Base
  has_many :user_stories
end

and a UserStory model :

class UserStory < ActiveRecord::Base
  belongs_to :backlog
end

On the show action of the Backlog controller, I want to display a link to create a UserStory that belongs to the current Backlog. I want it to redirect to the UserStory creation form.

<%= link_to 'New User story', "???" %>

if I put new_user_story_path, it creates a new UserStory but does not add it to the Backlog.

How should I do ?

Thanks !

Answer 1

You need to have nested routes.

app/config/rotues.rb

CodeGlot::Application.routes.draw do

  resources :backlogs do
    resources :user_stories
  end

end

Then you need to have a nested link:

index.html.erb # or whatever file

<%= link-to "New user story", new_backlog_user_story_path(backlog) %>

*make sure you have a varible backlog, otherwise the route will fail.

app/controllers/user_stories_controller.rb

before_filter :get_backlog

def get_backlog
    if params[:backlog_id]
        @backlog = Backlog.find(params[:backlog_id])
    end
end

def new
end

app/views/user_stories/new.html.erb

<div class="form">
<%= form_for([@backlog, @user_stories]) do |f| %>
  <div class="actions">
    <%= f.submit "Submit",  :disable_with => "Submitting..." %>
  </div>
<% end %>
</div>

app/models/backlog.rb

accepts_nested_attributes_for :user_stories