Most of the Rails files you’ll work with and create define classes. (They do so even when they don’t have explicit class definitions, as Rails performs some of its magic in the background.) The clearest place to work with objects in Rails is in the controller classes. To get started, therefore, go to the command line and create a new application and a new controller:
ruby script/generate controller Testbed index
If you’re using Heroku, instead of going to the command line, log in to Heroku and click on
the Create A New Application button from the My Apps page. You can rename it
“testbed” if you want, but the application name doesn’t matter much.
What does matter is that when the application editing screen opens, you click on the gear
menu near the bottom left, choose Generate, and enter
Testbed index. That will set things up for the rest of these examples.
For the rest of this appendix, there are only two files that matter: app/views/testbed/index.html.erb and app/controllers/testbed_controller.rb. For right now, replace the contents of app/views/testbed/index.html.erb with:
<%= @result %>
That will make it easy to see the results of the code in the controller, which is a
clearer place to explore Ruby. (
@result is a variable
whose value various examples will set.)
If you open app/controllers/testbed_controller.rb, you’ll see the code below. It doesn’t yet do anything, except tell the programmer what ...