Attributes - Transformations

Modify attribute values after coercion but before validation. Perfect for normalization, formatting, and data cleanup.

Declarations

Symbol References

Reference instance methods by symbol for dynamic value transformations:

class ProcessAnalytics < CMDx::Task
  attribute :options, transform: :compact_blank
end

Proc or Lambda

Use anonymous functions for dynamic value transformations:

class CacheContent < CMDx::Task
  # Proc
  attribute :expire_hours, transform: proc { |v| v * 2 }

  # Lambda
  attribute :compression, transform: ->(v) { v.to_s.upcase.strip[0..2]  }
end

Class or Module

Use any object that responds to call for reusable transformation logic:

class EmailNormalizer
  def call(value)
    value.to_s.downcase.strip
  end
end

class ProcessContacts < CMDx::Task
  # Class or Module
  attribute :email, transform: EmailNormalizer

  # Instance
  attribute :email, transform: EmailNormalizer.new
end

Validations

Validations run on transformed values, ensuring data consistency:

class ScheduleBackup < CMDx::Task
  # Coercions
  attribute :retention_days, type: :integer, transform: proc { |v| v.clamp(1, 5) }

  # Validations
  optional :frequency, transform: :downcase, inclusion: { in: %w[hourly daily weekly monthly] }
end