Inputs - Defaults

Provide fallback values for optional inputs. Defaults kick in when values aren't provided or are nil.

Declarations

Defaults compose with coercions, validations, and nested inputs:

Static Values

class OptimizeDatabase < CMDx::Task
  input :strategy, default: :incremental
  input :level, default: "basic"
  input :notify_admin, default: true
  input :timeout_minutes, default: 30
  input :indexes, default: []
  input :options, default: {}

  def work
    strategy        #=> :incremental
    level           #=> "basic"
    notify_admin    #=> true
    timeout_minutes #=> 30
    indexes         #=> []
    options         #=> {}
  end
end

Symbol References

Reference instance methods by symbol for dynamic default values:

class ProcessAnalytics < CMDx::Task
  input :granularity, default: :default_granularity

  def work
    # Your logic here...
  end

  private

  def default_granularity
    Current.user.premium? ? "hourly" : "daily"
  end
end

Proc or Lambda

Use anonymous functions for dynamic default values:

class CacheContent < CMDx::Task
  # Proc
  input :expire_hours, default: proc { Current.tenant.cache_duration || 24 }

  # Lambda
  input :compression, default: -> { Current.tenant.premium? ? "gzip" : "none" }
end

Class or Module

Any object responding to #call(task) works as a default:

class TenantDefaults
  def self.call(task)
    Current.tenant.cache_duration || 24
  end
end

class CacheContent < CMDx::Task
  input :expire_hours, default: TenantDefaults
end

Coercions and Validations

Defaults flow through the same pipeline as provided values — coercion, transform, then validation:

class ScheduleBackup < CMDx::Task
  # Default is coerced through :integer
  input :retention_days, default: "7", coerce: :integer

  # Default is validated against the inclusion list
  input :frequency, default: "daily", inclusion: { in: %w[hourly daily weekly monthly] }
end

Note

Defaults only apply when the resolved value is nil. An explicitly provided nil is treated as missing and the default fires. This applies equally whether the key was absent from context or the caller sent nil explicitly — both are "not provided".

Required + default

Defaults do not satisfy required:. A required input whose key is absent fails with is required before the default is consulted — so required: true, default: ... is effectively a contradiction. Use optional ..., default: instead when you want a fallback, and reserve required: for keys the caller must explicitly supply.