Form object pattern in Ruby on Rails - Mini Project: Build & Apply

Form Object Pattern in Rails

📖 Scenario: You are building a Rails app where users can register with their name and email. Instead of saving directly to the User model, you want to use a form object to handle validations and data processing cleanly.

🎯 Goal: Create a form object class that collects name and email, validates presence of both, and provides a save method to create a User record if valid.

📋 What You'll Learn

Create a form object class called RegistrationForm

Add name and email attributes to the form object

Validate presence of name and email in the form object

Implement a save method that creates a User if validations pass

💡 Why This Matters

🌍 Real World

Form objects help keep Rails controllers and models clean by handling complex form logic in one place.

💼 Career

Understanding form objects is useful for Rails developers to write maintainable and testable code in real applications.

1

Create the RegistrationForm class with attributes

Create a Ruby class called RegistrationForm that has attr_accessor for name and email.

Ruby on Rails

class RegistrationForm
  # Your code here
end

Need a hint?

Use attr_accessor to create getter and setter methods for name and email.

2

Add validations for presence of name and email

Inside the RegistrationForm class, include ActiveModel::Model and add validations to require presence of name and email.

Ruby on Rails

class RegistrationForm
  attr_accessor :name, :email
  # Your code here
end

Need a hint?

Include ActiveModel::Model to get validation features, then use validates for presence checks.

3

Implement the save method to create a User

Add a save method to RegistrationForm that returns false if the form is invalid. If valid, it creates a new User with name and email and saves it.

Ruby on Rails

class RegistrationForm
  include ActiveModel::Model
  attr_accessor :name, :email

  validates :name, presence: true
  validates :email, presence: true

  # Your code here
end

Need a hint?

Use valid? to check validations, then create a User with the form data.

4

Use the RegistrationForm in a controller action

In a controller action, create a new RegistrationForm instance with name and email from params, call save, and handle success or failure accordingly.

Ruby on Rails

def create
  # Your code here
end

Need a hint?

Instantiate the form with params, call save, then redirect or render based on result.