Rails%203%20In%20Action

248 CHAPTER 10 Tracking state
Listing 10.4 app/controllers/tickets_controller.rb
def show
@comment = @ticket.comments.build
end
This will use the build method on the comments association for your @ticket object
(which is set up by the find_ticketbefore_filter) to create a new Comment object
for the view’s form_for.
Next, you generate the Comment model so that you can define the comments association
on your Ticket model. This model’s going to need to have an attribute called
text for the text from the form, a foreign key to link it to a ticket, and another foreign
key to link to a user record. Let’s generate this model using this command:
rails g model comment text:text ticket_id:integer user_id:integer
Then run the migration for this model on both your development and test databases
by running these familiar commands:
rake db:migrate
rake db:test:prepare
With these done, your next stop is to add the associations to the Ticket and Comment
models. For this, you add this line to app/models/ticket.rb directly under the
accepts_nested_attributes_for :assets line:
has_many :comments
Add a validation to your Comment model to validate the presence of text for the
records by adding this line to app/models/comment.rb:
validates :text, :presence => true
This will help your second scenario pass, because it requires that an error message is
displayed when you don’t enter any text. You also add a belongs_to association definition
to this model, given that you have a user_id column in your comments table:
belongs_to :user
When you run your feature at this mid-point, you’re told that it can’t find the routing
helper that form_for is trying to use:
undefined method `ticket_comments_path' for ...
This is because you don’t have a nested route for comments inside your tickets
resource yet. To define one, you need to add it to config/routes.rb.
Currently in your config/routes.rb you’ve got the tickets resource nested inside the
projects resource with these lines:
resources :projects do
resources :tickets
end