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Setting The Default Page

Goals

    Now that the structure is complete, let's make the flow work smoothly.

    Currently when you go to your homepage you see the "Welcome aboard" message.

    It would be easier to use our app if the homepage went directly to the topics list.

    In this step we'll make that happen and learn a bit about routes in Rails.

Steps

Step 1: Add a root route

Open the file config/routes.rb in an editor.

Look for the line Rails.application.routes.draw at the beginning of the file, and add the line root 'topics#index' after it. When you are done the start of the file should look like this:

Rails.application.routes.draw do
  root 'topics#index'

Step 2: Confirm your changes

Go back to your homepage. You should be taken to the topics list automatically.

Explanation

  • 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 apartments.
  • 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 terminal.

    At the terminal type rails routes. You should get something that looks like this:

    $ rails routes

    Prefix Verb   URI Pattern                Controller#Action
    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
      root GET    /                          topics#index

    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 parenthesis is optional.

    You can also get this information on your site in development. Go to /rails/info and you'll see something like this:

    Screenshot of browser-based Rails routing info page

    You'll also see that table in whenever you try to access an invalid route (try /sandwich)

Exploring Routes

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:

$ rails console
>> app.topics_path
=> "/topics"
>> app.topics_url
=> "http://www.example.com/topics"

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).

Next Step:

Go on to Rails Architecture