Rails%203%20In%20Action

486 CHAPTER 17 Engines
This code has defined a Forem::TopicsController, which inherits seemingly from
ApplicationController. This is actually Forem::ApplicationController because
the class is being defined in the Forem module. The Forem::ApplicationController
will be where you put all your engine’s common controller things later on.
Right now, you need to define this missing index action. This action needs to
retrieve a list of all topics and then show them in the view. You’ll define this action by
changing your Forem::TopicsController to what’s shown in the following listing.
Listing 17.3 app/controllers/forem/topics_controller.rb
module Forem
class TopicsController < ApplicationController
def index
@topics = Forem::Topic.all
end
end
end
You’re namespacing your reference to the Forem::Topic model because it’s actually
Ruby that will be loading this class. If you referenced it without the Forem:: prefix,
then it would go looking for a normal Topic model that may belong to your application
or another engine. 19 At this point, you’re not going to have the Forem::Topic
model defined, and so you’ll need to generate that too. It will need to have a subject
attribute, as well has having a user_id attribute, which you’ll fill out later:
rails g model topic subject:text user_id:integer
As when you generated the topics controller, this model will also be namespaced. The
migration it generates is called create_forem_topics and will create a table called
forem_topics. This means the migration, model, and table will not clash with any similarly
named migration, model, or table in the main application.
To run this migration, run rake db:migrate as you would in an application. In an
engine, this will run the migration against the dummy application’s development database.
There’s no rake db:test:prepare in engines at the moment, and so you’ll have
to work around this by changing the dummy application’s config/database.yml file to
make the development and test databases the same. You’ll do this by using the code in
the following listing.
Listing 17.4 spec/dummy/config/database.yml
shared: &shared
adapter: sqlite3
database: db/development.sqlite3
pool: 5
timeout: 5000
development: