Ruby on Rails Interview Questions and Answers — Model — Part 1

9 min readSep 17
  • What is the role of a model in a Ruby on Rails application?
  • How do you define a validation rule for a model attribute in Rails?
  • Explain the purpose of associations in Rails models and provide an example.
  • What is ActiveRecord in the context of Rails models, and how does it work?
  • How do you create a new record in the database using a Rails model?

1. What is the role of a model in a Ruby on Rails application?

The role of a model in a Ruby on Rails application is to represent and manage the data and business logic of the application. In a Rails application following the Model-View-Controller (MVC) architectural pattern, the Model is one of the three core components, and its responsibilities include:

  • Data Representation: Models define the structure and attributes of the data entities within the application. Each model typically corresponds to a database table and its attributes map to its columns.
  • Database Interaction: Models are responsible for performing database operations, including creating, reading, updating, and deleting records (CRUD operations). Rails provides the ActiveRecord ORM layer to simplify database interactions, allowing developers to work with databases using Ruby code rather than writing raw SQL queries.
  • Business Logic: Models encapsulate the application’s business logic. This includes validation rules, calculations, and other operations related to the data they represent. Custom methods can be defined in models to encapsulate complex logic associated with specific data entities.
  • Associations: Models can define associations between each other to represent relationships in the data. For example, a “User” model can have a “has_many” association with a “Post” model to indicate that each user can have multiple posts. These associations facilitate the navigation and manipulation of related data.
  • Validations: Models include validation rules to ensure the integrity and consistency of data in the database. Rails provides a range of validation helpers to enforce rules such as presence, length, uniqueness, and custom…

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