Rails%203%20In%20Action

488 CHAPTER 17 Engines
You’re missing the new action in your Forem::TopicsController. This action will provide
the form that users can use to create a new topic.
17.5.5 The new action
You need to define the new action in the controller. This action and its related view will
provide the form for creating a topic and its first post. In this brand new action, you can
initialize a new topic and post with the following code underneath the index action:
def new
@topic = Forem::Topic.new
@topic.posts.build
end
There’s no association definition or even a model for the posts association yet, and so
you should create the model and then the correct associations. You can do this by running
this command:
rails g model post topic_id:integer text:text user_id:integer
You can then run rake db:migrate to create the forem_posts table. Next, you need to
set up both ends of this association, beginning with the Forem::Post model, which
needs to have this line inserted:
belongs_to :topic
Here you don’t need to tell Rails that the class of this association is Forem::Topic,
Rails will figure that out itself. In the Forem::Topic model, you need to set up the
other end of this association and accept nested attributes for it:
has_many :posts, :order => "created_at ASC"
accepts_nested_attributes_for :posts
You’re putting the accepts_nested_attributes_for in the Forem::Topic model
because when you submit the form for this action, you’ll be passing through the attributes
for the topic as well as nested attributes for the post. With the association now
defined in your Forem::Topic model, your new action will work.
The next step here is defining the view for this action, which you can do by putting
this code at app/views/forem/topics/new.html.erb:
New Topic
This view will render the partial at app/views/forem/topics/_form.html.erb, which you
need to define using the code in the following listing.
Listing 17.6 app/views/forem/topics/_form.html.erb