Controller generation in Ruby on Rails - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the default action created by rails generate controller?

You run rails generate controller Products. Which action is created by default in the generated controller?

A A <code>new</code> action is created by default.

B An <code>index</code> action is created by default.

C A <code>show</code> action is created by default.

D No actions are created by default; you must specify them explicitly.

💡 Hint

Think about what happens if you don't specify any actions when generating a controller.

When you run rails generate controller Products without specifying actions, Rails creates the controller file with no actions inside. You must explicitly list actions to generate them.

📝 Syntax

intermediate

Which command generates a controller with index and show actions?

Select the correct Rails command to generate a controller named Articles with index and show actions.

A rails generate controller Articles index show

B rails generate controller Articles --actions=index,show

C rails generate controller Articles -a index show

D rails generate controller Articles --with=index show

💡 Hint

Check the official Rails generator syntax for specifying actions.

The correct syntax is to list the actions after the controller name separated by spaces. Options like --actions or -a are not valid.

❓ state_output

advanced

What files are created by rails generate controller Users new edit?

After running rails generate controller Users new edit, which of the following files is NOT created?

A app/models/user.rb

B app/views/users/new.html.erb

C app/views/users/edit.html.erb

D app/controllers/users_controller.rb

💡 Hint

Consider what the controller generator creates versus the model generator.

The controller generator creates the controller file and view templates for the specified actions. It does not create model files.

🔧 Debug

advanced

Why does rails generate controller Posts show fail with uninitialized constant PostsController error?

You ran rails generate controller Posts show but when visiting /posts/show you get uninitialized constant PostsController. What is the most likely cause?

A The <code>show</code> action is missing inside <code>PostsController</code>.

B The route for <code>/posts/show</code> is missing in <code>config/routes.rb</code>.

C The controller file was not saved or generated properly.

D The model <code>Post</code> is not defined.

💡 Hint

The error means Rails cannot find the controller class at all.

uninitialized constant PostsController means Rails cannot find the controller class. This usually happens if the controller file was not created or saved correctly.

🧠 Conceptual

expert

What is the effect of adding --skip-routes when generating a controller?

You run rails generate controller Comments index --skip-routes. What is the effect of the --skip-routes option?

A It skips generating the controller file but creates views and routes.

B It prevents Rails from adding a route for the <code>index</code> action automatically.

C It disables generating view templates for the controller actions.

D It skips creating the controller test files.

💡 Hint

Think about what Rails normally does with routes when generating a controller.

By default, Rails adds a route for each generated action. The --skip-routes option prevents this automatic route creation.