Syrup::FormObject

This is a simple implementation of the FormObject... pattern?

Installation

$ gem install syrup_form_object

or in the Gemfile

gem 'syrup_form_object'

Examples

To update the Event class in your model

class Event < ActiveRecord::Base
  validates :start_date, presence: true
  validates :end_date, presence: true
end

You create the follwing form

class EventCreateForm < Syrup::FormObject
  has_one :event
  accepts_nested_attributes_for :event

  attribute :length_of_the_event, Integer
  validates :length_of_the_event, numericality:{greater_than: 0}

  def save
    if self.valid?
      end_date = event.start_date + length_of_the_event.hours
      event.end_date = end_date
      event.save
    else
      false
    end
  end
end

Create a controller similar to this one

class EventController < ApplicationController
  def new
    @event_form = EventCreateForm.new
  end

  def create
    @event_form = EventCreateForm.new(create_params)
    if @event_form.save
      redirect_to @event_form.event
    else
      render :new
    end
  end

  def create_params
    params.require(:event_create_form)
      .permit(:length_of_the_event)
      .permit(event_attributes: [:start_date])
  end
end

And in the template:

<%= form_for @event_form do %>
  <%= fields_for :event do %>
    <%= input_tag :start_date  %>
  <% end %>
  <%= input_tag :length_of_the_event  %>
<% end %>

Some sources for Form Objects

https://github.com/apotonick/reform An implementation of Form Objects

http://railscasts.com/episodes/416-form-objects

http://pivotallabs.com/form-backing-objects-for-fun-and-profit/

http://blog.codeclimate.com/blog/2012/10/17/7-ways-to-decompose-fat-activerecord-models/