strong_admin.rb

module StrongAdmin

  extend ActiveSupport::Concern

  def initialize
    @instance_name = active_admin_config.resource_name.downcase
    @klass = active_admin_config.resource_name.constantize

    @column_names = @klass.columns.map do |column|
      unless [:id, :created_at, :updated_at].include?(column.name.to_sym)
        case column.type
        when :datetime, :date, :time
          ([column.name.to_sym] + (1..5).inject([]) { |acc, x| acc << :"#{column.name}(#{x}i)" })
        else
          column.name.to_sym
        end
      end
    end.flatten

    super
  end

  def create
    resource_obj = instance_variable_set("@#{@instance_name}", @klass.new(params[@instance_name.to_sym].permit(*@column_names)))

    if resource_obj.save
      redirect_to send("admin_#{@instance_name}_path", resource_obj), notice: "Created #{@instance_name}."
    else
      render :new
    end
  end

  def update
    resource_obj = instance_variable_set("@#{@instance_name}", @klass.find(params[:id]))

    if resource_obj.update_attributes(params[@instance_name.to_sym].permit(*@column_names))
      redirect_to send("admin_#{@instance_name}_path", resource_obj), notice: "Updated #{@instance_name}."
    else
      render :edit
    end
  end

end

whatever.rb

ActiveAdmin.register Whatever do
  controller do; include StrongAdmin; end
end