How can I implement schema validation in Ruby?

How can I implement schema validation in Ruby?

You can use libraries like ActiveModel or Dry-validation for schema validation in Ruby. Would you like a code example?

Yes, please provide a code example using ActiveModel.

Sure! Here's a simple example:

class User
  include ActiveModel::Model

  attr_accessor :name, :email

  validates :name, presence: true
  validates :email, presence: true, format: { with: URI::MailTo::EMAIL_REGEXP }
end

user = User.new(name: 'John', email: '[email protected]')
user.valid? # => true

What if I want to add custom validation?

You can define a custom validation method in your model. For example:

validates :name, length: { minimum: 3 }
validate :name_must_be_unique

def name_must_be_unique
  if User.where(name: name).exists?
    errors.add(:name, 'must be unique')
  end
end