Custom Type Casting with Rails Attribute API

Rails’ Attribute API allows you to define custom attribute types with their own serialization and type casting logic, even for non-database backed attributes:

class Money < ActiveRecord::Type::Integer
  def cast(value)
    return super if value.kind_of?(Integer)
    return super(value.gsub(/[$,]/, '').to_i) if value.is_a?(String)
    super
  end
end

# Register the custom type
ActiveRecord::Type.register(:money, Money)

class Product < ApplicationRecord
  # Use the custom type for a database column
  attribute :price, :money

  # Or create a virtual attribute with type casting
  attribute :sale_price, :money, default: 0
end

product = Product.new(price: "$10,000")
product.price # => 10000

This is incredibly useful for handling non-primitive data types consistently throughout the application.