Ruby on Rails Ruby on Rails ActiveRecord & Database Management

Question 1

What is ActiveRecord in Ruby on Rails?

Accepted Answer

The ORM layer that maps Ruby objects to database tables

Answer

ActiveRecord is Rails' ORM (Object-Relational Mapping) that represents database tables as Ruby classes and rows as objects.

Question 2

Which Rails command generates a new database migration file?

Accepted Answer

rails generate migration AddTitleToArticles

Answer

`rails generate migration MigrationName` creates a timestamped migration file in db/migrate/ for database schema changes.

Question 3

What does `rails db:migrate` do?

Accepted Answer

Runs all pending migration files to update the database schema

Answer

`rails db:migrate` executes all pending migration files in chronological order to apply schema changes to the database.

Question 4

In ActiveRecord, what does `has_many :comments` in an Article model define?

Accepted Answer

A one-to-many association where an article has multiple comments

Answer

`has_many :comments` establishes a one-to-many association, allowing `article.comments` to retrieve all comments for that article.

Question 5

What is the purpose of `belongs_to :article` in a Comment model?

Accepted Answer

To define the inverse side of a has_many relationship, requiring an article_id foreign key

Answer

`belongs_to :article` declares the Comment as the child side of the relationship and expects an `article_id` column in the comments table.

Ruby on Rails Practice Test