reform2 custom predicates with dry-validation

form.rb

class Fund::CreateCallForm < BaseForm
  # your properties are here  
  # ...
  
  validation do
    configure do
      config.messages_file = 'config/locales/dry-validation/errors.yml'
      # don't forget about this option to be able to access your form object from your predicates
      option :form
      
      # include your custom predicates
      include Lion::Predicates
    end

    required(:fund).filled
    required(:name).filled
    required(:type) { filled? & included_in?(TRANSACTION_TYPES['Fund::Call']) }
    required(:call_date).filled
     
    # use your predicates
    required(:due_date).filled { filled? & after_or_equal_to?(:call_date) }
    required(:call_categories).value(min_size?: 1)
  end
end

predicates.rb

module Lion
  module Predicates
    def self.included(base)
      base.class_eval do
        def after?(value, current)
          value = form.send(value) if value.is_a?(Symbol)
          value = value.call if value.is_a?(Proc)

          value.present? && (current > value)
        end

        def after_or_equal_to?(value, current)
          value = form.send(value) if value.is_a?(Symbol)
          value = value.call if value.is_a?(Proc)

          value.present? && (current >= value)
        end

        def before?(value, current)
          value = form.send(value) if value.is_a?(Symbol)
          value = value.call if value.is_a?(Proc)

          value.present? && (current < value)
        end

        def before_or_equal_to?(value, current)
          value = form.send(value) if value.is_a?(Symbol)
          value = value.call if value.is_a?(Proc)

          value.present? && (current <= value)
        end

        def equal_to?(value, current)
          value = form.send(value) if value.is_a?(Symbol)
          value = value.call if value.is_a?(Proc)

          value.present? && (current === value)
        end
      end
    end
  end
end