composable_contracts.rb

SettingsSchema = Dry::Schema.JSON do
  optional(:custom_object).hash do
    required(:active).filled(:bool)
    optional(:entity_name).maybe(:string)
  end
end

module Macros
  def self.included(validator)
    validator.register_macro(:custom_object_entity_name) do
      next unless key? && key?(:active)

      active, entity_name = value.values_at(:active, :entity_name)
      if active && entity_name.blank?
        key("settings.custom_object.entity_name").failure("must be provided when custom_object is active")
      end
    end
  end
end

class CreateContract < Dry::Validation::Contract
  include Macros

  params do
    required(:owner).filled(type?: User)
    # ...
    optional(:settings).hash(Integrations::Bullhorn::Schemas::Settings)
  end

  rule("settings.custom_object").validate(:custom_object_entity_name)
end

class UpdateContract < Dry::Validation::Contract
  include Macros

  params do
    required(:my_object).filled(type?: MyObject)
    # ...
    optional(:settings).hash(Integrations::Bullhorn::Schemas::Settings)
  end

  rule("settings.custom_object").validate(:custom_object_entity_name)
end