code refactory on a small controller(thin controller fat model) - ruby-on-rails

Question

I have a controller action that is doing product listing, pagination and some filters, like category(from a dropdown), title(from a text-field), stock(from a checkbox)
This is my controller:
class ProductsController < ApplicationController
def index
#products = Product.where(active:1).where("title LIKE ?","%#{params[:title]}%")
if params[:stock]
#products=#products.where("stock = 0")
end
if params[:category]
#products=#products.where("category_id LIKE ?","#{params[:category]}")
end
#products= #products.paginate(:page => params[:page])
#categories= Category.all
end
And my model is:
class Product < ActiveRecord::Base
belongs_to :category
...some validations...
end
What could I change in order that my controller would become thinner? Thanks

Answer 1

Model
class Product < ActiveRecord:::Base
scope :active, where(active: 1)
def self.with_stock(stock=nil)
return where(stock: 0) if stock
self
end
def self.categorized(category=nil)
return self.where(category: category) if category
self
end
def self.titled(title=nil)
return self.where("title LIKE ?", 'title') if title
self
end
def self.list(params)
title = params[:title]
category = params[:category]
page = params[:page]
self.titled(title).with_stock(stock).categorized(category)
.paginate(page).active
end
end
Controller
def index
#products = Product.list(params)
end
Do not ship Category in controller. Do it in template/partial. ONE instance variable from controller only.

Answer 2

I propose the specific refactoring style:
controller
class ProductsController < ApplicationController
def index
#products = Product.titled params[:title]
#products = #products.in_stock if params[:stock]
#products = #products.category params[:category] if params[:category]
#products = #products.paginate :page => params[:page]
#categories = Category.all
end
end
model
class Product < ActiveRecord::Base
belongs_to :category
...
scope :titled, proc {| title | where(active:1).where("title LIKE ?","%#{title}%")
scope :in_stock, proc { where("stock = 0") }
scope :category, proc {| category | where("category_id LIKE ?","#{category}") }
end

Answer 3

If your intent is just to the controller become thinner, you could move the logic to the model.
ProductController.rb
#products = Product.some_method(params)
Product.rb
def self.some_method(params)
if params[:stock]
where("stock = 0 AND active = 1 AND title LIKE ?","%#{params[:title]}%")
end
if params[:category]
where("active = 1 AND category_id LIKE ? AND title LIKE ?", "#{params[:category]}", "%#{params[:title]}%")
end

Answer 4

Using thin controller, fat model principle.
controller:
class ProductsController < ApplicationController
def index
#products = Product.active(params).paginate(page: params[:page])
#categories = Category.all
end
end
model:
class Product < ActiveRecord::Base
belongs_to :category
def self.active(params)
products = where(active:1).where("title LIKE ?","%#{params[:title]}%")
if params[:stock]
products = products.where("stock = 0")
end
if params[:category]
products = products.where("category_id LIKE ?","#{params[:category]}")
end
end
end