ActiveModel::Modelで簡単に検索機能追加 ref: http://qiita.com/mnishiguchi/items/4681bb16f440d6032eaf

file0.txt

class SearchForm
  include ActiveModel::Model

  attr_accessor :q
end

file1.txt

class Ingredient < ActiveRecord::Base

  scope :sorted, ->{ order(name: :asc) }
  scope :named, ->(q) { where("name ilike ?", "%#{q}%") }

file2.txt

class Ingredient < ActiveRecord::Base

  scope :sorted, ->{ order(name: :asc) }
  scope :named, ->(q) { where("name ilike ?", "%#{q}%") }

file3.txt

class IngredientsController < ApplicationController

  before_action :search_ingredients, only: :index

  def index
  end

def search_ingredients
  @search = SearchForm.new(params[:search_form])
  @ingredients = if @search.q.present?
    then Ingredient.all.named(@search.q)
    else Ingredient.all
  end.sorted
end

file4.txt

.filter_wrapper{ style: "margin-bottom: 20px;" }
  = form_for @search, url: ingredients_path, html: {method: :get}, class: "form-horizontal" do |f|
    .form-group
      .input-group
        = f.search_field :q, class: "form-control"
        %span.input-group-btn
          = f.button fa_icon("search"), class: "btn btn-default"

file5.txt

class IngredientsController < ApplicationController

  before_action :search_ingredients, only: :index

  def index
  end

  private

    def search_ingredients
      @search = SearchForm.new(params[:search_form])
      @ingredients = if @search.q.present?
        then Ingredient.all.named(@search.q)
        else Ingredient.all
      end.sorted
    end
end

使用したModel関連Gems

gem 'pg',    '~> 0.17.1'  # PostgreSQLを使用するため

使用したView関連Gems

gem "font-awesome-rails"  # fa_icon("アイコン名")を利用しアイコンを表示するため
gem 'haml-rails'          # HAMLでテンプレートを書くため
gem 'bootstrap-sass'      # Bootstrapを利用するため