Uniqueness validation in Ruby on Rails - Mini Project: Build & Apply

Uniqueness validation

📖 Scenario: You are building a simple Rails app to manage users. Each user must have a unique email address so that no two users can register with the same email.

🎯 Goal: Create a Rails model User with an email attribute. Add a uniqueness validation to ensure no duplicate emails can be saved.

📋 What You'll Learn

Create a User model with an email attribute

Add a uniqueness validation on the email attribute in the User model

Use Rails built-in validation syntax

Ensure the validation is case insensitive

💡 Why This Matters

🌍 Real World

Ensuring unique emails is essential for user registration systems to avoid account conflicts.

💼 Career

Understanding Rails validations and database constraints is key for backend developers building secure and reliable web apps.

1

Create the User model with email attribute

Create a Rails model called User with a string attribute email.

Ruby on Rails

# Create User model with email attribute
# Your code here

Need a hint?

In Rails, the model class inherits from ApplicationRecord. The email attribute comes from the database migration.

2

Add uniqueness validation configuration

Add a validation line in the User model to check uniqueness of the email attribute with case insensitivity.

Ruby on Rails

class User < ApplicationRecord
  # Add uniqueness validation for email here
  # Your code here
end

Need a hint?

Use validates :email, uniqueness: { case_sensitive: false } to ensure emails are unique ignoring case.

3

Add presence validation for email

Add a validation line in the User model to ensure the email attribute is present (not empty).

Ruby on Rails

class User < ApplicationRecord
  validates :email, uniqueness: { case_sensitive: false }
  # Add presence validation for email here
  # Your code here
end

Need a hint?

Use validates :email, presence: true to require an email value.

4

Add database index for uniqueness

Add a unique index on the email column in the database migration to enforce uniqueness at the database level.

Ruby on Rails

# In your migration file, add a unique index on email
# Your code here

Need a hint?

Use add_index :users, :email, unique: true in the migration to prevent duplicates in the database.