Learning Goals

By the end of this lesson, you will know/be able to:

• Understand the 5 pieces of information rake routes gives us.
• Use a route helper to easily refer to a relative and absolute path.
• Understand the difference between what _url and _path return when combined with a routes prefix.
• Find a routes prefix and use that prefix to build a helper.
• Understand how to use link_to and button_to view helpers.

Vocab

• routes
• path helper
• url helper

WarmUp

• How have you been sending a user to another route, say in your tests or in a controller?
• Read the following sections of the Rails Guides for Routing:
  • 1.1 Connecting URLs to Code
  • 2.1 Resources on the Web
  • 2.2 CRUD, Verbs and Actions
  • 4.6 Restricting the Routes Created
• What is the syntax for creating a single route?
• What shortcut does Rails give us to create multiple routes at once?

Routes

With your partner, take a look at the entries in the table that rake routes gives you and fill out the table below in your notebook or on your computer.

Fill in your answers here.

Large group share

• What is the path helper for each CRUD action? Which ones take an argument?
• What is the url helper for each? How do these compare to the path helpers?

Using prefix names to make path helpers

• Rails will use the “prefix” column to build our “path helpers”, we just need to add _path to the end of the prefix name
• Generally, any row that does not include a “prefix” uses the same “prefix” as the line above it

Passing Parameters to Path Helpers

Any time a path helper needs a dynamic parameter, like :id we MUST pass a value to the path helper.

Best practice is to pass the entire object to the path helper, such as:

journey = Artist.create(name: 'Journey')
visit artist_path(journey)

Rails will check if the object has an ID value and build the path helper appropriately.

Turn & Talk

• What happens if we forget to pass a parameter to a path helper that needs it?
• What error do we see?
• Practice reading the ENTIRE error message to understand what’s going on

Point out to students that the error message will start to look like a “missing route” error, but when they read the ENTIRE error, it will actually tell them the path helper is missing a parameter.

Using rake routes as a debugging tool

We can use rake routes as a debugging tool for our path helpers:

• examine the edit path helper for an album:

edit_album GET /albums/:id/edit(.:format) albums#edit

We can see in the rake routes output that we need a “dynamic parameter” in our URI path, called /:id/. Here, rake routes is telling us exactly what the parameter is called, and that also indicates how we can access this value in our params hash: params[:id]

If you add a custom route to config/routes.rb with its own “dynamic parameter”, like:

• get '/albums/:album_id', to: 'albums#show' and run rake routes again
• GET /albums/:album_id(.:format) albums#show

Again, rake routes shows us a dynamic parameter in the URI path, called :album_id, and we would also access this as params[:album_id]

Be sure to remove any custom routes for albums

We only want to see you using path helpers moving forward, no exceptions

Independent Practice

Update your test suite to use path helpers instead of direct paths (i.e. “/songs”)

Partnered Workshop

Research how to use link helpers with your path helpers to create a navigation bar. This navigation bar would contain a link that leads to all songs and one that leads to all artists. It also includes a link to go home. Your home would show links to create a new song or artist.

Partnered Share

Turn to a new partner and share out how you used path helpers to dry up your code.

WrapUp

• What does artists_path evaluate to outside of a link helper?
• What does artists_url evaluate to outside of a link helper?
• What does artist_path(@artist) give you? Why do you need to pass it @artist? Which other routes need you to pass a resource?