generate_message

# File activemodel/lib/active_model/error.rb, line 64
    def self.generate_message(attribute, type, base, options) # :nodoc:
      type = options.delete(:message) if options[:message].is_a?(Symbol)
      value = (attribute != :base ? base.read_attribute_for_validation(attribute) : nil)

      options = {
        model: base.model_name.human,
        attribute: base.class.human_attribute_name(attribute, { base: base }),
        value: value,
        object: base
      }.merge!(options)

      if base.class.respond_to?(:i18n_scope)
        i18n_scope = base.class.i18n_scope.to_s
        attribute = attribute.to_s.remove(/\[\d+\]/)

        defaults = base.class.lookup_ancestors.flat_map do |klass|
          [ :"#{i18n_scope}.errors.models.#{klass.model_name.i18n_key}.attributes.#{attribute}.#{type}",
            :"#{i18n_scope}.errors.models.#{klass.model_name.i18n_key}.#{type}" ]
        end
        defaults << :"#{i18n_scope}.errors.messages.#{type}"

        catch(:exception) do
          translation = I18n.translate(defaults.first, **options.merge(default: defaults.drop(1), throw: true))
          return translation unless translation.nil?
        end unless options[:message]
      else
        defaults = []
      end

      defaults << :"errors.attributes.#{attribute}.#{type}"
      defaults << :"errors.messages.#{type}"

      key = defaults.shift
      defaults = options.delete(:message) if options[:message]
      options[:default] = defaults

      I18n.translate(key, **options)
    end