Convention over configuration principle in Ruby on Rails - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Rails Naming Conventions

In Rails, which file name will Rails automatically associate with the UsersController class following the convention over configuration principle?

A users_controller.rb

B UsersController.rb

C user_controller.rb

D userscontroller.rb

💡 Hint

Think about how Rails expects controller files to be named in snake_case matching the controller class name.

Rails expects controller files to be named in snake_case matching the controller class name. For UsersController, the file should be users_controller.rb. This is a key example of convention over configuration.

❓ component_behavior

intermediate

Default Database Table Name for a Model

Given a Rails model class named ProductCategory, what is the default database table name Rails will use without any configuration?

A product_categories

B productcategory

C product_category

D ProductCategories

💡 Hint

Rails pluralizes and snake_cases model class names to get table names.

Rails automatically converts model class names from CamelCase to snake_case and pluralizes them to get the table name. So ProductCategory becomes product_categories.

📝 Syntax

advanced

Identifying the Correct Route Helper Method

In a Rails app with a resource declared as resources :orders, which helper method will generate the path to the new order form following Rails conventions?

A order_new_path

B create_order_path

C new_order_path

D orders_new_path

💡 Hint

Rails uses a specific pattern for new resource routes: new__path.

Rails generates route helper methods based on resource names. For the new form of orders, the helper is new_order_path.

🔧 Debug

advanced

Why Does This Rails View Template Not Render?

You have a controller named ArticlesController. You created a view template named show.html.erb inside the folder app/views/article. Why does Rails not render this template by default?

A The template file should be named show.html.html

B Rails requires the template to be in app/views/shared

C The controller name should be ArticleController

D The folder name should be plural: app/views/articles

💡 Hint

Check the folder naming convention for views matching controller names.

Rails expects the view folder to be the pluralized form of the controller name. Since the controller is ArticlesController, the folder must be articles, not article.

❓ state_output

expert

Effect of Skipping Convention in Model Associations

Consider these two Rails models:

class User < ApplicationRecord
has_many :posts
end

class Post < ApplicationRecord
belongs_to :author, class_name: 'User'
end

What will happen if you try to access post.author without specifying the foreign key in the Post model, assuming the posts table has a user_id column?

A Rails will use user_id automatically for author association

B Rails will raise an error because it expects author_id column by default

C Rails will return nil because the association is not configured properly

D Rails will correctly find the user because of class_name and user_id column

💡 Hint

Think about how Rails infers foreign keys from association names.

When you use belongs_to :author, class_name: 'User', Rails expects a foreign key named author_id by default. Since the table has user_id instead, Rails cannot find the association without specifying foreign_key: 'user_id'.