Now that the structure is complete, let's make the flow work smoothly.
Currently when you go to <http://localhost:3000> you see the "Yay! You’re on Rails!" message.
It would be easier to use our app if <http://localhost:3000> went directly to the topics list.
In this step we'll make that happen and learn a bit about routes in Rails.
step "Add a root route" do
message "Open the file `config/routes.rb` in an editor."
message "Search the file for the line `resources :topics`. It will be near the top."
message "Right above that line, add a new line: `root 'topics#index'`. When you are done the file should look like this:"
source_code :ruby, <<-RUBY
# For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html
step "Remove the comment (optional)" do
Near the bottom, there is a line that starts with a `#`. This is called a
comment. It is ignored by ruby and is used for reference or further
explanation of nearby code. If you want, you can remove it, or keep it
there to look at later. It's totally up to you!
step "Confirm your changes" do
message "Go back to <http://localhost:3000/>. You should be taken to the topics list automatically."
span " delete any text after 'amazonaws.com', or click to preview running
application in the editor again"
* `root 'topics#index'` is a Rails route that says the default
address for your site is `topics#index`. `topics#index` is the topics
list page (the topics controller with the index action).
* Rails routes control how URLs (web addresses) get matched with
code on the server. Similar to how addresses match with houses and
* The file `config/routes.rb` is like an address directory listing the
possible addresses and which code goes with each one.
* `routes.rb` uses some shortcuts so it doesn't always show all the
possible URLs. To explore the URLs in more detail we can use the
At the terminal type `rails routes`. You should get something that
looks like this:
$ rails routes
Prefix Verb URI Pattern Controller#Action
root GET / topics#index
topics GET /topics(.:format) topics#index
POST /topics(.:format) topics#create
new_topic GET /topics/new(.:format) topics#new
edit_topic GET /topics/:id/edit(.:format) topics#edit
topic GET /topics/:id(.:format) topics#show
PATCH /topics/:id(.:format) topics#update
PUT /topics/:id(.:format) topics#update
DELETE /topics/:id(.:format) topics#destroy
This shows all the URLs your application responds to. The code that starts
with colons are variables so `:id` means the id number of the record. The
code in parentheses is optional.
You can also get this information on your site in development. Go to
message "Navigate to `https://<your-preview-url>.amazonaws.com/rails/info/routes`"
and you'll see something like this:
<img src='img/rails4_rails_info_routing.png' alt='Screenshot of browser-based Rails routing info page'>
You'll also see that table whenever you try to access an invalid route,
step "Exploring Routes (optional)" do
Now you can have a look at the paths that are available in your app.
Let's try looking at one of the topics routes we just generated.
Open up your rails console and play:
console_without_message "$ rails console"
message "`app` is a special object that represents your entire application.
You can ask it about its routes (as we just did), play with its
database connections, or make pseudo-web requests against it with
`get` or `post` (and lots more)."