Inputs - Transformations

Transforms are the tidy-up step: trim strings, normalize emails, clamp numbers — whatever polish you want after coercion but before validation. Validators always see the cleaned-up value.

Processing pipeline

Every input walks the same line:

flowchart LR
    Source --> Default --> Coerce --> Transform --> Validate

Stage	What happens
Source	Pull raw value from context, method, proc, or callable
Default	If still nil, apply default:
Coerce	Turn into the target type (coerce:)
Transform	Massage the coerced value (transform:)
Validate	Run presence, format, inclusion, etc.

So: coerce first, then transform, then validate. Plan rules accordingly.

Declarations

Symbol references

Call a method on the value if it exists (value.send(symbol)); otherwise CMDx tries task.send(symbol, value):

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

Proc or Lambda

Inline tweaks without extra classes:

class CacheContent < CMDx::Task
  input :expire_hours, transform: proc { |v| v * 2 }
  input :compression, transform: ->(v) { v.to_s.upcase.strip[0..2] }
end

Class or Module

Share logic with #call(value, task):

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

class PhoneNormalizer
  def call(value, _task)
    value.to_s.gsub(/\D/, "")
  end
end

class ProcessContacts < CMDx::Task
  input :email, transform: EmailNormalizer
  input :phone, transform: PhoneNormalizer.new
end

Pipeline position

Because validation runs last, you can coerce → fix → then check:

class ScheduleBackup < CMDx::Task
  input :retention_days, coerce: :integer, transform: proc { |v| v.clamp(1, 5) }
  optional :frequency, transform: :downcase, inclusion: { in: %w[hourly daily weekly monthly] }
end

Optional + nil

Transforms only run when the coerced value is non-nil. If the key is missing, there’s no default, and the input is optional, the pipeline stops early — no transform, no validator. Need the transform every time? Add a default: or make the input required.