simple reform example

event_controller.rb

class EventsController < ApplicationController
  def index
    @events = Event.all
  end

  def show
    @event = Event.find(params[:id])
  end

  def new
  end

  def create
    if form.validate(event_params.merge(creator: current_user))
      form.save
      redirect_to form.model
    else
      render :new
    end
  end

  def edit
  end

  def update
    if form.validate(event_params.merge(creator: current_user))
      form.save
      redirect_to form.model
    else
      render :edit
    end
  end

  private

  def form
    @form ||= begin
      if params[:id].present?
        EventForm.new(Event.find(params[:id]))
      else
        EventForm.new(Event.new)
      end
    end
  end
  helper_method :form

  def event_params
    params.require(:event).permit! # (:title, :desc)
  end
end