submit_default_value

# File actionview/lib/action_view/helpers/form_helper.rb, line 2681
        def submit_default_value
          object = convert_to_model(@object)
          key    = object ? (object.persisted? ? :update : :create) : :submit

          model = if object.respond_to?(:model_name)
            object.model_name.human
          else
            @object_name.to_s.humanize
          end

          defaults = []
          # Object is a model and it is not overwritten by as and scope option.
          if object.respond_to?(:model_name) && object_name.to_s == model.downcase
            defaults << :"helpers.submit.#{object.model_name.i18n_key}.#{key}"
          else
            defaults << :"helpers.submit.#{object_name}.#{key}"
          end
          defaults << :"helpers.submit.#{key}"
          defaults << "#{key.to_s.humanize} #{model}"

          I18n.t(defaults.shift, model: model, default: defaults)
        end