Roll your own managed exposure

README.md

Simple proof of concept for keeping instance variables out of the views while also allowing for some reuse of variable declarations.

References:

• http://thepugautomatic.com/2013/05/locals/
• http://blog.voxdolo.me/a-diatribe-on-maintaining-state.html

items_controller.rb

# Updated to use `locals` and a getter

class ItemsController < ApplicationController

  # don't need before_action anymore
  #
  # before_action :set_item, only: [:show, :edit, :update, :destroy]

  def index
    render locals: { items: items }
  end

  def show
    render locals: { item: item }
  end

  def new
    render locals: { item: Item.new }
  end

  def edit
    render locals: { item: item }
  end

  def create
    self.item = Item.new(item_params)
    if item.save
      redirect_to item, notice: 'Item was successfully created.'
    else
      render :new, locals: { item: item }
    end
  end

  def update
    if item.update(item_params)
      redirect_to item, notice: 'Item was successfully updated.'
    else
      render :edit, locals: { item: item }
    end
  end

  def destroy
    item.destroy
    redirect_to items_url, notice: 'Item was successfully destroyed.'
    end
  end

  private
    def items
      @item ||= Item.all
    end

    def item
      @item ||= Item.find(params[:id])
    end

    def item=(item)
      @item = item
    end

    def item_params
      params[:item]
    end
end

items_controller.scaffolded.rb

# Scaffolded controller

class ItemsController < ApplicationController
  before_action :set_item, only: [:show, :edit, :update, :destroy]

  def index
    @items = Item.all
  end

  def show
  end

  def new
    @item = Item.new
  end

  def edit
  end

  def create
    @item = Item.new(item_params)
    if @item.save
      redirect_to @item, notice: 'Item was successfully created.'
    else
      render :new
    end
  end

  def update
    if @item.update(item_params)
      redirect_to @item, notice: 'Item was successfully updated.'
    else
      render :edit
    end
  end

  def destroy
    @item.destroy
    redirect_to items_url, notice: 'Item was successfully destroyed.'
    end
  end

  private
    def set_item
      @item = Item.find(params[:id])
    end

    def item_params
      params[:item]
    end
end