Convention over configuration principle in Ruby on Rails - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a Rails model using convention over configuration.

Ruby on Rails

class User < ApplicationRecord
  # Rails automatically maps this model to the [1] table
end

Drag options to blanks, or click blank then click option'

Amembers

Buser_data

Caccounts

Dusers

Attempts:

3 left

💡 Hint

Common Mistakes

Using a singular table name instead of plural

Using a custom table name without configuration

Rails automatically maps the model User to the users table by following naming conventions.

2fill in blank

medium

Complete the code to create a controller action that renders the default view using Rails conventions.

Ruby on Rails

class PostsController < ApplicationController
  def index
    @posts = Post.all
    render [1]
  end
end

Drag options to blanks, or click blank then click option'

Anil

B:show

C:index

D:new

Attempts:

3 left

💡 Hint

Common Mistakes

Explicitly rendering a different view name

Using render with a symbol that does not match the action

In Rails, if you omit the render call or pass nil, it renders the default view matching the action name.

3fill in blank

hard

Fix the error in the route definition by completing the blank with the correct Rails convention.

Ruby on Rails

Rails.application.routes.draw do
  resources :[1]
end

Drag options to blanks, or click blank then click option'

Apost

Bposts

CPost

DPosts

Attempts:

3 left

💡 Hint

Common Mistakes

Using singular or capitalized resource names in routes

Mixing case sensitivity in route names

Rails expects resource names in routes to be lowercase and plural, so posts is correct.

4fill in blank

hard

Fill both blanks to define a model with a custom table name using Rails conventions.

Ruby on Rails

class [1] < ApplicationRecord
  self.table_name = '[2]'
end

Drag options to blanks, or click blank then click option'

AUserProfile

Buser_profiles

CUserprofiles

Duserprofile

Attempts:

3 left

💡 Hint

Common Mistakes

Using singular or camel case for the table name

Not setting self.table_name when the table name differs

When the table name differs from the Rails convention, you set self.table_name to the actual table name, which is usually lowercase and plural.

5fill in blank

hard

Fill all three blanks to complete a Rails migration that creates a table following conventions.

Ruby on Rails

class Create[1] < ActiveRecord::Migration[6.1]
  def change
    create_table :[2] do |t|
      t.string :[3]
      t.timestamps
    end
  end
end

Drag options to blanks, or click blank then click option'

AProducts

Bproducts

Cname

Dproduct_name

Attempts:

3 left

💡 Hint

Common Mistakes

Using singular or lowercase class names

Using camel case for table names

Using complex or non-standard column names

The migration class name is camel case and plural, the table name is lowercase plural, and the column name follows simple naming conventions.

Practice

1. What does the Convention over configuration principle in Rails primarily help with?

easy

A. Automatically generating user interface designs

B. Reducing the amount of setup code by following naming rules

C. Making Rails apps run faster by optimizing queries

D. Forcing developers to write detailed configuration files

Solution

1. Step 1: Understand the principle's goal

   Convention over configuration means Rails guesses what you want if you follow its naming rules.

2. Step 2: Identify the main benefit

   This reduces the need to write extra setup or configuration code manually.

3. Final Answer:

   Reducing the amount of setup code by following naming rules -> Option B

4. Quick Check:

   Convention over configuration = less setup code [OK]

Hint: Think: Rails guesses if you follow rules, so less setup [OK]

Common Mistakes:

• Confusing it with performance optimization
• Thinking it forces more configuration files
• Assuming it auto-generates UI designs

2. Which of the following is the correct Rails convention for naming a model class representing users?

easy

A. class User < ApplicationRecord

B. class users < ApplicationRecord

C. class user < ApplicationRecord

D. class USER < ApplicationRecord

Solution

1. Step 1: Recall Rails naming conventions for models

   Model class names are singular and start with a capital letter, e.g., User.

2. Step 2: Check syntax correctness

   class User < ApplicationRecord uses correct class name capitalization and inherits from ApplicationRecord.

3. Final Answer:

   class User < ApplicationRecord -> Option A

4. Quick Check:

   Model class names are singular and capitalized [OK]

Hint: Model names are singular and capitalized classes [OK]

Common Mistakes:

• Using plural or lowercase class names
• Not capitalizing the class name
• Using all uppercase letters

3. Given a Rails model named Article, which database table name will Rails expect by convention?

medium

A. articles

B. article

C. Article

D. article_table

Solution

1. Step 1: Recall Rails table naming convention

   Rails expects database tables to be plural lowercase versions of model names.

2. Step 2: Apply to the model 'Article'

   The plural lowercase form is 'articles'.

3. Final Answer:

   articles -> Option A

4. Quick Check:

   Model 'Article' maps to table 'articles' [OK]

Hint: Model name pluralized lowercase = table name [OK]

Common Mistakes:

• Using singular table names
• Using capitalized table names
• Adding extra suffixes like '_table'

4. You created a model class class Person < ApplicationRecord but named the database table people_data. What is the main issue here?

medium

A. Rails will use the people_data table without problems

B. Rails will automatically find the table despite the name difference

C. Rails will raise an error because the table name does not follow convention

D. Rails will ignore the model and use a default table

Solution

1. Step 1: Understand default table naming

   Rails expects the table name to be the plural form of the model name, here 'people'.

2. Step 2: Check mismatch impact

   Since the table is named 'people_data', Rails won't find it automatically and will raise an error unless explicitly told.

3. Final Answer:

   Rails will raise an error because the table name does not follow convention -> Option C

4. Quick Check:

   Table name mismatch causes error unless configured [OK]

Hint: Table name must match plural model name or configure explicitly [OK]

Common Mistakes:

• Assuming Rails guesses any table name
• Thinking Rails silently ignores the model
• Believing Rails auto-corrects table names

5. You want to create a Rails controller for managing blog posts. According to convention, which controller class name and file path are correct?

hard

A. class BlogPostController < ApplicationController in app/controllers/blog_post_controller.rb

B. class blogpostscontroller < ApplicationController in app/controllers/blogposts_controller.rb

C. class BlogPosts < ApplicationController in app/controllers/blog_posts.rb

D. class BlogPostsController < ApplicationController in app/controllers/blog_posts_controller.rb

Solution

1. Step 1: Recall controller naming conventions

   Controllers are plural, camel case with 'Controller' suffix, e.g., BlogPostsController.

2. Step 2: Recall file path conventions

   File names are snake_case plural with '_controller.rb' suffix, e.g., blog_posts_controller.rb.

3. Final Answer:

   class BlogPostsController < ApplicationController in app/controllers/blog_posts_controller.rb -> Option D

4. Quick Check:

   Controller class plural + Controller suffix, file snake_case plural [OK]

Hint: Controller class plural CamelCase + file snake_case plural_controller.rb [OK]

Common Mistakes:

• Using singular controller class names
• Incorrect file naming or casing
• Omitting 'Controller' suffix